Re: [PATCH v6] drm/bridge: add it6505 driver

[Andrzej Hajda <a.hajda@xxxxxxxxxxx>]

Hi Allen,

Sorry for long delay.

W dniu 08.12.2020 o 11:58, allen pisze:
> This adds support for the iTE IT6505.
> This device can convert DPI signal to DP output.
>
> From: Allen Chen <allen.chen@xxxxxxxxxx>
> Signed-off-by: Jitao Shi <jitao.shi@xxxxxxxxxxxx>
> Signed-off-by: Pi-Hsun Shih <pihsun@xxxxxxxxxxxx>
> Signed-off-by: Yilun Lin <yllin@xxxxxxxxxx>
> Signed-off-by: Hermes Wu <hermes.wu@xxxxxxxxxx>
> Signed-off-by: Allen Chen <allen.chen@xxxxxxxxxx>
> ---
>   drivers/gpu/drm/bridge/Kconfig      |    7 +
>   drivers/gpu/drm/bridge/Makefile     |    1 +
>   drivers/gpu/drm/bridge/ite-it6505.c | 3343 +++++++++++++++++++++++++++
>   3 files changed, 3351 insertions(+)
>   create mode 100644 drivers/gpu/drm/bridge/ite-it6505.c
>
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index e4110d6ca7b3c..25d34d7196004 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -74,6 +74,13 @@ config DRM_LONTIUM_LT9611UXC
>   	  HDMI signals
>   	  Please say Y if you have such hardware.
>   
> +config DRM_ITE_IT6505
> +	tristate "ITE IT6505 DisplayPort bridge"
> +	depends on OF
> +	select DRM_KMS_HELPER
> +	help
> +	  ITE IT6505 DisplayPort bridge chip driver.
> +
>   config DRM_LVDS_CODEC
>   	tristate "Transparent LVDS encoders and decoders support"
>   	depends on OF
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index 86e7acc76f8d6..2b2f8f0b5b0fa 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -4,6 +4,7 @@ obj-$(CONFIG_DRM_CHRONTEL_CH7033) += chrontel-ch7033.o
>   obj-$(CONFIG_DRM_DISPLAY_CONNECTOR) += display-connector.o
>   obj-$(CONFIG_DRM_LONTIUM_LT9611) += lontium-lt9611.o
>   obj-$(CONFIG_DRM_LONTIUM_LT9611UXC) += lontium-lt9611uxc.o
> +obj-$(CONFIG_DRM_ITE_IT6505) += ite-it6505.o


Please keep alphabetic order.


>   obj-$(CONFIG_DRM_LVDS_CODEC) += lvds-codec.o
>   obj-$(CONFIG_DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW) += megachips-stdpxxxx-ge-b850v3-fw.o
>   obj-$(CONFIG_DRM_NXP_PTN3460) += nxp-ptn3460.o
> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> new file mode 100644
> index 0000000000000..5e76719a51a4a
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> @@ -0,0 +1,3343 @@
> +// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +/*
> + * Copyright (c) 2020, The Linux Foundation. All rights reserved.
> + */
> +#include <linux/bits.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/extcon.h>
> +#include <linux/fs.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/types.h>
> +#include <linux/wait.h>
> +
> +#include <crypto/hash.h>
> +
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_bridge.h>
> +#include <drm/drm_crtc.h>
> +#include <drm/drm_crtc_helper.h>
> +#include <drm/drm_dp_helper.h>
> +#include <drm/drm_edid.h>
> +#include <drm/drm_hdcp.h>
> +#include <drm/drm_print.h>
> +#include <drm/drm_probe_helper.h>
> +
> +#include <sound/hdmi-codec.h>
> +
> +#define REG_IC_VER 0x04
> +
> +#define REG_RESET_CTRL 0x05
> +#define VIDEO_RESET BIT(0)
> +#define AUDIO_RESET BIT(1)
> +#define ALL_LOGIC_RESET BIT(2)
> +#define AUX_RESET BIT(3)
> +#define HDCP_RESET BIT(4)
> +
> +#define INT_STATUS_01 0x06
> +#define INT_MASK_01 0x09
> +#define INT_HPD_CHANGE BIT(0)
> +#define INT_RECEIVE_HPD_IRQ BIT(1)
> +#define INT_SCDT_CHANGE BIT(2)
> +#define INT_HDCP_FAIL BIT(3)
> +#define INT_HDCP_DONE BIT(4)
> +
> +#define INT_STATUS_02 0x07
> +#define INT_MASK_02 0x0A
> +#define INT_AUX_CMD_FAIL BIT(0)
> +#define INT_HDCP_KSV_CHECK BIT(1)
> +#define INT_AUDIO_FIFO_ERROR BIT(2)
> +
> +#define INT_STATUS_03 0x08
> +#define INT_MASK_03 0x0B
> +#define INT_LINK_TRAIN_FAIL BIT(4)
> +#define INT_VID_FIFO_ERROR BIT(5)
> +#define INT_IO_LATCH_FIFO_OVERFLOW BIT(7)
> +
> +#define REG_SYSTEM_STS 0x0D
> +#define INT_STS BIT(0)
> +#define HPD_STS BIT(1)
> +#define VIDEO_STB BIT(2)
> +
> +#define REG_LINK_TRAIN_STS 0x0E
> +#define LINK_STATE_CR BIT(2)
> +#define LINK_STATE_EQ BIT(3)
> +#define LINK_STATE_NORP BIT(4)
> +
> +#define REG_BANK_SEL 0x0F
> +#define REG_CLK_CTRL0 0x10
> +#define M_PCLK_DELAY 0x03
> +
> +#define REG_AUX_OPT 0x11
> +#define AUX_AUTO_RST BIT(0)
> +#define AUX_FIX_FREQ BIT(3)
> +
> +#define REG_DATA_CTRL0 0x12
> +#define VIDEO_LATCH_EDGE BIT(4)
> +#define ENABLE_PCLK_COUNTER BIT(7)
> +
> +#define REG_PCLK_COUNTER_VALUE 0x13
> +
> +#define REG_501_FIFO_CTRL 0x15
> +#define RST_501_FIFO BIT(1)
> +
> +#define REG_TRAIN_CTRL0 0x16
> +#define FORCE_LBR BIT(0)
> +#define LANE_COUNT_MASK 0x06
> +#define LANE_SWAP BIT(3)
> +#define SPREAD_AMP_5 BIT(4)
> +#define FORCE_CR_DONE BIT(5)
> +#define FORCE_EQ_DONE BIT(6)
> +
> +#define REG_TRAIN_CTRL1 0x17
> +#define AUTO_TRAIN BIT(0)
> +#define MANUAL_TRAIN BIT(1)
> +#define FORCE_RETRAIN BIT(2)
> +
> +#define REG_AUX_CTRL 0x23
> +#define CLR_EDID_FIFO BIT(0)
> +#define AUX_USER_MODE BIT(1)
> +#define AUX_NO_SEGMENT_WR BIT(6)
> +#define AUX_EN_FIFO_READ BIT(7)
> +
> +#define REG_AUX_ADR_0_7 0x24
> +#define REG_AUX_ADR_8_15 0x25
> +#define REG_AUX_ADR_16_19 0x26
> +#define REG_AUX_OUT_DATA0 0x27
> +
> +#define REG_AUX_CMD_REQ 0x2B
> +#define AUX_BUSY BIT(5)
> +
> +#define REG_AUX_DATA_0_7 0x2C
> +#define REG_AUX_DATA_8_15 0x2D
> +#define REG_AUX_DATA_16_23 0x2E
> +#define REG_AUX_DATA_24_31 0x2F
> +
> +#define REG_AUX_DATA_FIFO 0x2F
> +
> +#define REG_AUX_ERROR_STS 0x9F
> +#define M_AUX_REQ_FAIL 0x03
> +
> +#define REG_HDCP_CTRL1 0x38
> +#define HDCP_CP_ENABLE BIT(0)
> +
> +#define REG_HDCP_TRIGGER 0x39
> +#define HDCP_TRIGGER_START  BIT(0)
> +#define HDCP_TRIGGER_CPIRQ  BIT(1)
> +#define HDCP_TRIGGER_KSV_DONE  BIT(4)
> +#define HDCP_TRIGGER_KSV_FAIL BIT(5)
> +
> +#define REG_HDCP_CTRL2 0x3A
> +#define HDCP_AN_SEL BIT(0)
> +#define HDCP_AN_GEN BIT(1)
> +#define HDCP_HW_HPDIRQ_ACT BIT(2)
> +#define HDCP_EN_M0_READ BIT(5)
> +
> +#define REG_M0_0_7 0x4C
> +#define REG_AN_0_7 0x4C
> +#define REG_SP_CTRL0 0x58
> +#define REG_IP_CTRL1 0x59
> +#define REG_IP_CTRL2 0x5A
> +
> +#define REG_LINK_DRV 0x5C
> +#define DRV_HS BIT(1)
> +
> +#define REG_DRV_LN_DATA_SEL 0x5D
> +
> +#define REG_AUX 0x5E
> +
> +#define REG_VID_BUS_CTRL0 0x60
> +#define IN_DDR BIT(2)
> +#define DDR_CD (0x01 << 6)
> +
> +#define REG_VID_BUS_CTRL1 0x61
> +#define TX_FIFO_RESET BIT(1)
> +
> +#define REG_INPUT_CTRL 0xA0
> +#define INPUT_HSYNC_POL BIT(0)
> +#define INPUT_VSYNC_POL BIT(2)
> +#define INPUT_INTERLACED BIT(4)
> +
> +#define REG_INPUT_HTOTAL 0xA1
> +#define REG_INPUT_HACTIVE_START 0xA3
> +#define REG_INPUT_HACTIVE_WIDTH 0xA5
> +#define REG_INPUT_HFRONT_PORCH 0xA7
> +#define REG_INPUT_HSYNC_WIDTH 0xA9
> +#define REG_INPUT_VTOTAL 0xAB
> +#define REG_INPUT_VACTIVE_START 0xAD
> +#define REG_INPUT_VACTIVE_WIDTH 0xAF
> +#define REG_INPUT_VFRONT_PORCH 0xB1
> +#define REG_INPUT_VSYNC_WIDTH 0xB3
> +
> +#define REG_AUDIO_SRC_CTRL 0xB8
> +#define M_AUDIO_I2S_EN 0x0F
> +#define EN_I2S0 BIT(0)
> +#define EN_I2S1 BIT(1)
> +#define EN_I2S2 BIT(2)
> +#define EN_I2S3 BIT(3)
> +#define AUDIO_FIFO_RESET BIT(7)
> +
> +#define REG_AUDIO_FMT 0xB9
> +#define REG_AUDIO_FIFO_SEL 0xBA
> +
> +#define REG_AUDIO_CTRL0 0xBB
> +#define AUDIO_FULL_PKT BIT(4)
> +#define AUDIO_16B_BOUND BIT(5)
> +
> +#define REG_AUDIO_CTRL1 0xBC
> +#define REG_AUDIO_INPUT_FREQ 0xBE
> +
> +#define REG_IEC958_STS0 0xBF
> +#define REG_IEC958_STS1 0xC0
> +#define REG_IEC958_STS2 0xC1
> +#define REG_IEC958_STS3 0xC2
> +#define REG_IEC958_STS4 0xC3
> +
> +#define REG_HPD_IRQ_TIME 0xC9
> +#define REG_AUX_DEBUG_MODE 0xCA
> +#define REG_AUX_OPT2 0xCB
> +#define REG_HDCP_OPT 0xCE
> +#define REG_USER_DRV_PRE 0xCF
> +
> +#define REG_DATA_MUTE_CTRL 0xD3
> +#define ENABLE_ENHANCED_FRAME BIT(0)
> +#define ENABLE_AUTO_VIDEO_FIFO_RESET BIT(1)
> +#define EN_VID_MUTE BIT(4)
> +#define EN_AUD_MUTE BIT(5)
> +
> +#define REG_TIME_STMP_CTRL 0xD4
> +#define EN_ENHANCE_VID_STMP BIT(0)
> +#define EN_ENHANCE_AUD_STMP BIT(2)
> +#define M_STAMP_STEP 0x30
> +#define EN_SSC_GAT BIT(6)
> +
> +#define REG_INFOFRAME_CTRL 0xE8
> +#define EN_AVI_PKT BIT(0)
> +#define EN_AUD_PKT BIT(1)
> +#define EN_MPG_PKT BIT(2)
> +#define EN_GEN_PKT BIT(3)
> +#define EN_VID_TIME_STMP BIT(4)
> +#define EN_AUD_TIME_STMP BIT(5)
> +#define EN_VID_CTRL_PKT (EN_AVI_PKT | EN_VID_TIME_STMP)
> +#define EN_AUD_CTRL_PKT (EN_AUD_PKT | EN_AUD_TIME_STMP)
> +
> +#define REG_AUDIO_N_0_7 0xDE
> +#define REG_AUDIO_N_8_15 0xDF
> +#define REG_AUDIO_N_16_23 0xE0
> +
> +#define REG_AVI_INFO_DB1 0xE9
> +#define REG_AVI_INFO_DB2 0xEA
> +#define REG_AVI_INFO_DB3 0xEB
> +#define REG_AVI_INFO_DB4 0xEC
> +#define REG_AVI_INFO_DB5 0xED
> +#define REG_AVI_INFO_SUM 0xF6
> +
> +#define REG_AUD_INFOFRAM_DB1 0xF7
> +#define REG_AUD_INFOFRAM_DB2 0xF8
> +#define REG_AUD_INFOFRAM_DB3 0xF9
> +#define REG_AUD_INFOFRAM_DB4 0xFA
> +#define REG_AUD_INFOFRAM_SUM 0xFB
> +
> +/* the following six registers are in bank1 */
> +#define REG_DRV_0_DB_800_MV 0x7E
> +#define REG_PRE_0_DB_800_MV 0x7F
> +#define REG_PRE_3P5_DB_800_MV 0x81
> +#define REG_SSC_CTRL0 0x88
> +#define REG_SSC_CTRL1 0x89
> +#define REG_SSC_CTRL2 0x8A
> +
> +#define RBR DP_LINK_BW_1_62
> +#define HBR DP_LINK_BW_2_7
> +#define HBR2 DP_LINK_BW_5_4
> +#define HBR3 DP_LINK_BW_8_1
> +
> +/* Vendor option */
> +#define HDCP_DESIRED 1
> +#define MAX_LANE_COUNT 4
> +#define MAX_LINK_RATE HBR
> +#define AUTO_TRAIN_RETRY 3
> +#define MAX_HDCP_DOWN_STREAM_COUNT 10
> +#define MAX_CR_LEVEL 0x03
> +#define MAX_EQ_LEVEL 0x03
> +#define AUX_WAIT_TIMEOUT_MS 15
> +#define AUX_FIFO_MAX_SIZE 32
> +#define PIXEL_CLK_DELAY 1
> +#define PIXEL_CLK_INVERSE 0
> +#define ADJUST_PHASE_THRESHOLD 80000
> +#define DPI_PIXEL_CLK_MAX 95000
> +#define HDCP_SHA1_FIFO_LEN (MAX_HDCP_DOWN_STREAM_COUNT * 5 + 10)
> +#define DEFAULT_PWR_ON 0
> +#define DEFAULT_DRV_HOLD 0
> +
> +#define AUDIO_SELECT I2S
> +#define AUDIO_TYPE LPCM
> +#define AUDIO_SAMPLE_RATE SAMPLE_RATE_48K
Better drop this define and use SAMPLE_RATE_48K directly.
> +#define AUDIO_CHANNEL_COUNT 2
> +
> +/*
> + * 0: Standard I2S
> + * 1: 32bit I2S
> + */
> +#define I2S_INPUT_FORMAT 1


Maybe it would be more usable to use defines as follows:

+#define I2S_INPUT_FORMAT_STANDARD 0

+#define I2S_INPUT_FORMAT_32BIT 1

+#define I2S_INPUT_FORMAT_DEFAULT I2S_INPUT_FORMAT_32BIT

Less lines, no comments, self-documenting code. Even more I guess you can drop I2S_INPUT_FORMAT_DEFAULT and use I2S_INPUT_FORMAT_32BIT instead.

> +
> +/*
> + * 0: Left-justified
> + * 1: Right-justified
> + */
> +#define I2S_JUSTIFIED 0
> +
> +/*
> + * 0: Data delay 1T correspond to WS
> + * 1: No data delay correspond to WS
> + */
> +#define I2S_DATA_DELAY 0
> +
> +/*
> + * 0: Left channel
> + * 1: Right channel
> + */
> +#define I2S_WS_CHANNEL 0
> +
> +/*
> + * 0: MSB shift first
> + * 1: LSB shift first
> + */
> +#define I2S_DATA_SEQUENCE 0

ditto for above 4 defines


> +
> +/*
> + * Audio Sample Word Length
> + * WORD_LENGTH_16BIT
> + * WORD_LENGTH_18BIT
> + * WORD_LENGTH_20BIT
> + * WORD_LENGTH_24BIT
> + */
> +#define AUDIO_WORD_LENGTH WORD_LENGTH_24BIT

ditto, moreover using symbols not yet defined is confusing/ugly, even if 
the (pre)compiler allows it.

> +
> +enum aux_cmd_type {
> +	CMD_AUX_NATIVE_READ = 0x0,
> +	CMD_AUX_NATIVE_WRITE = 0x5,
> +	CMD_AUX_I2C_EDID_READ = 0xB,
> +};
> +
> +enum aux_cmd_reply {
> +	REPLY_ACK,
> +	REPLY_NACK,
> +	REPLY_DEFER,
> +};
> +
> +enum link_train_status {
> +	LINK_IDLE,
> +	LINK_BUSY,
> +	LINK_OK,
> +};
> +
> +enum hdcp_state {
> +	HDCP_AUTH_IDLE,
> +	HDCP_AUTH_GOING,
> +	HDCP_AUTH_DONE,
> +};
> +
> +struct it6505_platform_data {
> +	struct regulator *pwr18;
> +	struct regulator *ovdd;
> +	struct gpio_desc *gpiod_reset;
> +};
> +
> +enum it6505_audio_select {
> +	I2S = 0,
> +	SPDIF,
> +};
> +
> +enum it6505_audio_sample_rate {
> +	SAMPLE_RATE_24K = 0x6,
> +	SAMPLE_RATE_32K = 0x3,
> +	SAMPLE_RATE_48K = 0x2,
> +	SAMPLE_RATE_96K = 0xA,
> +	SAMPLE_RATE_192K = 0xE,
> +	SAMPLE_RATE_44_1K = 0x0,
> +	SAMPLE_RATE_88_2K = 0x8,
> +	SAMPLE_RATE_176_4K = 0xC,
> +};
> +
> +enum it6505_audio_type {
> +	LPCM = 0,
> +	NLPCM,
> +	DSS,
> +};
> +
> +enum it6505_audio_word_length {
> +	WORD_LENGTH_16BIT = 0,
> +	WORD_LENGTH_18BIT,
> +	WORD_LENGTH_20BIT,
> +	WORD_LENGTH_24BIT,
> +};
> +
> +struct it6505_audio_data {
> +	enum it6505_audio_select select;
> +	enum it6505_audio_sample_rate sample_rate;
> +	enum it6505_audio_type type;
> +	enum it6505_audio_word_length word_length;
> +	u8 channel_count;
> +	u8 i2s_input_format;
> +	u8 i2s_justified;
> +	u8 i2s_data_delay;
> +	u8 i2s_ws_channel;
> +	u8 i2s_data_sequence;
> +};
> +
> +struct it6505_audio_sample_rate_map {
> +	enum it6505_audio_sample_rate rate;
> +	int sample_rate_value;
> +};
> +
> +struct it6505_drm_dp_link {
> +	unsigned char revision;
> +	unsigned int rate;
> +	unsigned int num_lanes;
> +	unsigned long capabilities;
> +};
> +
> +struct it6505 {
> +	struct drm_dp_aux aux;
> +	struct drm_bridge bridge;
> +	struct i2c_client *client;
> +	struct edid *edid;
> +	struct drm_connector connector;
> +	struct it6505_drm_dp_link link;
> +	struct it6505_platform_data pdata;
> +	struct mutex extcon_lock;
> +	struct mutex mode_lock;
> +	struct mutex aux_lock;
> +	struct regmap *regmap;
> +	struct drm_display_mode video_info;
> +	struct notifier_block event_nb;
> +	struct extcon_dev *extcon;
> +	struct work_struct extcon_wq;
> +	enum drm_connector_status connector_status;
> +	enum link_train_status link_state;
> +	struct work_struct link_works;
> +	u8 dpcd[DP_RECEIVER_CAP_SIZE];
> +	u8 lane_count;
> +	u8 link_rate_bw_code;
> +	u8 sink_count;
> +	bool step_train;
> +	bool branch_device;
> +	bool enable_ssc;
> +	bool lane_swap_disabled;
> +	bool lane_swap;
> +	bool powered;
> +	u32 afe_setting;
> +	enum hdcp_state hdcp_status;
> +	struct delayed_work hdcp_work;
> +	struct work_struct hdcp_wait_ksv_list;
> +	struct completion wait_edid_complete;
> +	u8 auto_train_retry;
> +	bool hdcp_desired;
> +	bool is_repeater;
> +	u8 hdcp_down_stream_count;
> +	u8 bksvs[DRM_HDCP_KSV_LEN];
> +	u8 sha1_input[HDCP_SHA1_FIFO_LEN];
> +	bool enable_enhanced_frame;
> +	hdmi_codec_plugged_cb plugged_cb;
> +	struct device *codec_dev;
> +	struct delayed_work delayed_audio;
> +	struct it6505_audio_data audio;
> +
> +	/* it6505 driver hold option */
> +	bool enable_drv_hold;
> +};
> +
> +struct it6505_step_train_para {
> +	u8 voltage_swing[MAX_LANE_COUNT];
> +	u8 pre_emphasis[MAX_LANE_COUNT];
> +};
> +
> +/*
> + * Vendor option afe settings for different platforms
> + * 0: without FPC cable
> + * 1: with FPC cable
> + */
> +
> +static u8 const afe_setting_table[][3] = {
> +	{0x82, 0x00, 0x45},
> +	{0x93, 0x2A, 0x85}
> +};
> +
> +static const struct it6505_audio_sample_rate_map audio_sample_rate_map[] = {
> +	{SAMPLE_RATE_24K, 24000},
> +	{SAMPLE_RATE_32K, 32000},
> +	{SAMPLE_RATE_48K, 48000},
> +	{SAMPLE_RATE_96K, 96000},
> +	{SAMPLE_RATE_192K, 192000},
> +	{SAMPLE_RATE_44_1K, 44100},
> +	{SAMPLE_RATE_88_2K, 88200},
> +	{SAMPLE_RATE_176_4K, 176400},
> +};
> +
> +static const struct regmap_range it6505_bridge_volatile_ranges[] = {
> +	{ .range_min = 0, .range_max = 0xFF },
> +};
> +
> +static const struct regmap_access_table it6505_bridge_volatile_table = {
> +	.yes_ranges = it6505_bridge_volatile_ranges,
> +	.n_yes_ranges = ARRAY_SIZE(it6505_bridge_volatile_ranges),
> +};
> +
> +static const struct regmap_config it6505_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.volatile_table = &it6505_bridge_volatile_table,
> +	.cache_type = REGCACHE_NONE,
> +};
> +
> +static int it6505_read(struct it6505 *it6505, unsigned int reg_addr)
> +{
> +	unsigned int value;
> +	int err;
> +	struct device *dev = &it6505->client->dev;
> +
> +	err = regmap_read(it6505->regmap, reg_addr, &value);
> +	if (err < 0) {
> +		DRM_DEV_ERROR(dev, "read failed reg[0x%x] err: %d", reg_addr,
> +			      err);
> +		return err;
> +	}
> +
> +	return value;
> +}
> +
> +static int it6505_write(struct it6505 *it6505, unsigned int reg_addr,
> +		      unsigned int reg_val)
> +{
> +	int err;
> +	struct device *dev = &it6505->client->dev;
> +
> +	err = regmap_write(it6505->regmap, reg_addr, reg_val);
> +
> +	if (err < 0) {
> +		DRM_DEV_ERROR(dev, "write failed reg[0x%x] = 0x%x err = %d",
> +			      reg_addr, reg_val, err);
> +		return err;
> +	}
> +
> +	return 0;
> +}
> +
> +static int it6505_set_bits(struct it6505 *it6505, unsigned int reg,
> +			 unsigned int mask, unsigned int value)
> +{
> +	int err;
> +	struct device *dev = &it6505->client->dev;
> +
> +	err = regmap_update_bits(it6505->regmap, reg, mask, value);
> +	if (err < 0) {
> +		DRM_DEV_ERROR(
> +			dev, "write reg[0x%x] = 0x%x mask = 0x%x failed err %d",
> +			reg, value, mask, err);
> +		return err;
> +	}
> +
> +	return 0;
> +}
> +
> +static void it6505_debug_print(struct it6505 *it6505, unsigned int reg,
> +			     const char *prefix)
> +{
> +	struct device *dev = &it6505->client->dev;
> +	int val;
> +
> +	if (likely(!(__drm_debug & DRM_UT_DRIVER)))
> +		return;
> +
> +	val = it6505_read(it6505, reg);
> +	if (val < 0)
> +		DRM_DEV_DEBUG_DRIVER(dev, "%s reg[%02x] read error (%d)",
> +				     prefix, reg, val);
> +	else
> +		DRM_DEV_DEBUG_DRIVER(dev, "%s reg[%02x] = 0x%02x", prefix, reg,
> +				     val);
> +}
> +
> +static int it6505_dpcd_read(struct it6505 *it6505, unsigned long offset)
> +{
> +	u8 value;
> +	int ret;
> +	struct device *dev = &it6505->client->dev;
> +
> +	ret = drm_dp_dpcd_readb(&it6505->aux, offset, &value);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "DPCD read failed [0x%lx] ret: %d", offset,
> +			      ret);
> +		return ret;
> +	}
> +	return value;
> +}
> +
> +static int it6505_dpcd_write(struct it6505 *it6505, unsigned long offset,
> +			     unsigned long datain)
> +{
> +	int ret;
> +	struct device *dev = &it6505->client->dev;
> +
> +	ret = drm_dp_dpcd_writeb(&it6505->aux, offset, datain);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "DPCD write failed [0x%lx] ret: %d", offset,
> +			      ret);
> +		return ret;
> +	}
> +	return 0;
> +}
> +
> +static int it6505_get_dpcd(struct it6505 *it6505, int offset, u8 *dpcd, int num)
> +{
> +	int ret;
> +	struct device *dev = &it6505->client->dev;
> +
> +	ret = drm_dp_dpcd_read(&it6505->aux, offset, dpcd, num);
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "ret = %d DPCD[0x%x] = 0x%*ph", ret, offset,
> +			     num, dpcd);
> +
> +	return 0;
> +}
> +
> +static void it6505_dump(struct it6505 *it6505)
> +{
> +	unsigned int i, j;
> +	u8 regs[16];
> +	struct device *dev = &it6505->client->dev;
> +
> +	for (i = 0; i <= 0xff; i += 16) {
> +		for (j = 0; j < 16; j++)
> +			regs[j] = it6505_read(it6505, i + j);
> +
> +		DRM_DEV_DEBUG_DRIVER(dev, "[0x%02x] = %16ph", i, regs);
> +	}
> +}
> +
> +static bool it6505_get_sink_hpd_status(struct it6505 *it6505)
> +{
> +	int reg_0d;
> +
> +	reg_0d = it6505_read(it6505, REG_SYSTEM_STS);
> +
> +	if (reg_0d < 0)
> +		return false;
> +
> +	return !!(reg_0d & HPD_STS);


Drop !!, compiler will perform correct conversion.


> +}
> +
> +static int it6505_read_word(struct it6505 *it6505, unsigned int reg)
> +{
> +	int val0, val1;
> +
> +	val0 = it6505_read(it6505, reg);
> +	if (val0 < 0)
> +		return val0;
> +
> +	val1 = it6505_read(it6505, reg + 1);
> +	if (val1 < 0)
> +		return val1;
> +
> +	return (val1 << 8) | val0;
> +}
> +
> +static void it6505_calc_video_info(struct it6505 *it6505)
> +{
> +	struct device *dev = &it6505->client->dev;
> +	int hsync_pol, vsync_pol, interlaced;
> +	int htotal, hdes, hdew, hfph, hsyncw;
> +	int vtotal, vdes, vdew, vfph, vsyncw;
> +	int rddata, i, pclk, sum = 0;
> +
> +	usleep_range(10000, 15000);
> +	it6505_write(it6505, REG_BANK_SEL, 0x00);
> +	rddata = it6505_read(it6505, REG_INPUT_CTRL);
> +	hsync_pol = rddata & INPUT_HSYNC_POL;
> +	vsync_pol = (rddata & INPUT_VSYNC_POL) >> 2;
> +	interlaced = (rddata & INPUT_INTERLACED) >> 4;
> +
> +	htotal = it6505_read_word(it6505, REG_INPUT_HTOTAL) & 0x1FFF;
> +	hdes = it6505_read_word(it6505, REG_INPUT_HACTIVE_START) & 0x1FFF;
> +	hdew = it6505_read_word(it6505, REG_INPUT_HACTIVE_WIDTH) & 0x1FFF;
> +	hfph = it6505_read_word(it6505, REG_INPUT_HFRONT_PORCH) & 0x1FFF;
> +	hsyncw = it6505_read_word(it6505, REG_INPUT_HSYNC_WIDTH) & 0x1FFF;
> +
> +	vtotal = it6505_read_word(it6505, REG_INPUT_VTOTAL) & 0xFFF;
> +	vdes = it6505_read_word(it6505, REG_INPUT_VACTIVE_START) & 0xFFF;
> +	vdew = it6505_read_word(it6505, REG_INPUT_VACTIVE_WIDTH) & 0xFFF;
> +	vfph = it6505_read_word(it6505, REG_INPUT_VFRONT_PORCH) & 0xFFF;
> +	vsyncw = it6505_read_word(it6505, REG_INPUT_VSYNC_WIDTH) & 0xFFF;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "hsync_pol:%d, vsync_pol:%d, interlaced:%d",
> +			     hsync_pol, vsync_pol, interlaced);
> +	DRM_DEV_DEBUG_DRIVER(dev, "hactive_start:%d, vactive_start:%d",
> +			     hdes, vdes);
> +
> +	for (i = 0; i < 10; i++) {
> +		it6505_set_bits(it6505, REG_DATA_CTRL0, ENABLE_PCLK_COUNTER,
> +				ENABLE_PCLK_COUNTER);
> +		usleep_range(10000, 15000);
> +		it6505_set_bits(it6505, REG_DATA_CTRL0, ENABLE_PCLK_COUNTER,
> +				0x00);
> +		rddata = it6505_read_word(it6505, REG_PCLK_COUNTER_VALUE) &
> +			 0xFFF;
> +
> +		sum += rddata;
> +	}
> +
> +	if (sum == 0) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "calc video timing error");
> +		return;
> +	}
> +
> +	sum /= 10;
> +	pclk = 13500 * 2048 / sum;
> +	it6505->video_info.clock = pclk;
> +	it6505->video_info.hdisplay = hdew;
> +	it6505->video_info.hsync_start = hdew + hfph;
> +	it6505->video_info.hsync_end = hdew + hfph + hsyncw;
> +	it6505->video_info.htotal = htotal;
> +	it6505->video_info.vdisplay = vdew;
> +	it6505->video_info.vsync_start = vdew + vfph;
> +	it6505->video_info.vsync_end = vdew + vfph + vsyncw;
> +	it6505->video_info.vtotal = vtotal;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, DRM_MODE_FMT,
> +			     DRM_MODE_ARG(&it6505->video_info));
> +}
> +
> +static int it6505_drm_dp_link_probe(struct drm_dp_aux *aux,
> +				    struct it6505_drm_dp_link *link)
> +{
> +	u8 values[3];
> +	int err;
> +
> +	memset(link, 0, sizeof(*link));
> +
> +	err = drm_dp_dpcd_read(aux, DP_DPCD_REV, values, sizeof(values));
> +	if (err < 0)
> +		return err;
> +
> +	link->revision = values[0];
> +	link->rate = drm_dp_bw_code_to_link_rate(values[1]);
> +	link->num_lanes = values[2] & DP_MAX_LANE_COUNT_MASK;
> +
> +	if (values[2] & DP_ENHANCED_FRAME_CAP)
> +		link->capabilities = 1;
> +
> +	return 0;
> +}
> +
> +static int it6505_drm_dp_link_power_up(struct drm_dp_aux *aux,
> +				       struct it6505_drm_dp_link *link)
> +{
> +	u8 value;
> +	int err;
> +
> +	/* DP_SET_POWER register is only available on DPCD v1.1 and later */
> +	if (link->revision < 0x11)
> +		return 0;
> +
> +	err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value);
> +	if (err < 0)
> +		return err;
> +
> +	value &= ~DP_SET_POWER_MASK;
> +	value |= DP_SET_POWER_D0;
> +
> +	err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
> +	if (err < 0)
> +		return err;
> +
> +	/*
> +	 * According to the DP 1.1 specification, a "Sink Device must exit the
> +	 * power saving state within 1 ms" (Section 2.5.3.1, Table 5-52, "Sink
> +	 * Control Field" (register 0x600).
> +	 */
> +	usleep_range(1000, 2000);
> +
> +	return 0;
> +}
> +
> +static void it6505_clear_int(struct it6505 *it6505)
> +{
> +	it6505_write(it6505, REG_BANK_SEL, 0x00);
> +	it6505_write(it6505, INT_STATUS_01, 0xFF);
> +	it6505_write(it6505, INT_STATUS_02, 0xFF);
> +	it6505_write(it6505, INT_STATUS_03, 0xFF);
> +}
> +
> +static void it6505_int_mask_enable(struct it6505 *it6505)
> +{
> +	it6505_write(it6505, REG_BANK_SEL, 0x00);
> +	it6505_write(it6505, INT_MASK_01, 0x1F);
> +	it6505_write(it6505, INT_MASK_02, 0x07);
> +	it6505_write(it6505, INT_MASK_03, 0xB0);
> +}
> +
> +static void it6505_int_mask_disable(struct it6505 *it6505)
> +{
> +	it6505_write(it6505, REG_BANK_SEL, 0x00);
> +	it6505_write(it6505, INT_MASK_01, 0x00);
> +	it6505_write(it6505, INT_MASK_02, 0x00);
> +	it6505_write(it6505, INT_MASK_03, 0x00);
> +}
> +
> +static void it6505_lane_termination_on(struct it6505 *it6505)
> +{
> +	int regcf;
> +
> +	regcf = it6505_read(it6505, REG_USER_DRV_PRE);
> +
> +	if (regcf == 0xF0)
> +		it6505_set_bits(it6505, REG_DRV_LN_DATA_SEL, 0x80, 0x00);
> +
> +	if (regcf == 0x70) {
> +		if (it6505->lane_swap) {
> +			switch (it6505->lane_count) {
> +			case 1:
> +			case 2:
> +				it6505_set_bits(it6505, REG_DRV_LN_DATA_SEL,
> +						0x0C, 0x08);
> +				break;
> +			default:
> +				it6505_set_bits(it6505, REG_DRV_LN_DATA_SEL,
> +						0x0C, 0x0C);
> +				break;
> +			}
> +		} else {
> +			switch (it6505->lane_count) {
> +			case 1:
> +			case 2:
> +				it6505_set_bits(it6505, REG_DRV_LN_DATA_SEL,
> +						0x0C, 0x04);
> +				break;
> +			default:
> +				it6505_set_bits(it6505, REG_DRV_LN_DATA_SEL,
> +						0x0C, 0x0C);
> +				break;
> +			}
> +		}
> +	}
> +}
> +
> +static void it6505_lane_termination_off(struct it6505 *it6505)
> +{
> +	int regcf;
> +
> +	regcf = it6505_read(it6505, REG_USER_DRV_PRE);
> +
> +	if (regcf == 0xF0)
> +		it6505_set_bits(it6505, REG_DRV_LN_DATA_SEL, 0x80, 0x80);
> +
> +	if (regcf == 0x70)
> +		it6505_set_bits(it6505, REG_DRV_LN_DATA_SEL, 0x0C, 0x00);
> +}
> +
> +static void it6505_lane_power_on(struct it6505 *it6505)
> +{
> +	it6505_set_bits(it6505, REG_LINK_DRV, 0xF1,
> +			(it6505->lane_swap ?
> +				 GENMASK(7, 8 - it6505->lane_count) :
> +				 GENMASK(3 + it6505->lane_count, 4)) |
> +				0x01);
> +}
> +
> +static void it6505_lane_power_off(struct it6505 *it6505)
> +{
> +	it6505_set_bits(it6505, REG_LINK_DRV, 0xF0, 0x00);
> +}
> +
> +static void it6505_lane_off(struct it6505 *it6505)
> +{
> +	it6505_lane_power_off(it6505);
> +	it6505_lane_termination_off(it6505);
> +}
> +
> +static void it6505_aux_termination_on(struct it6505 *it6505)
> +{
> +	int regcf;
> +
> +	regcf = it6505_read(it6505, REG_USER_DRV_PRE);
> +
> +	if (regcf == 0xF0)
> +		it6505_lane_termination_on(it6505);
> +
> +	if (regcf == 0x70)
> +		it6505_set_bits(it6505, REG_DRV_LN_DATA_SEL, 0x80, 0x80);
> +}
> +
> +static void it6505_aux_power_on(struct it6505 *it6505)
> +{
> +	it6505_set_bits(it6505, REG_AUX, 0x02, 0x02);
> +}
> +
> +static void it6505_aux_on(struct it6505 *it6505)
> +{
> +	it6505_aux_power_on(it6505);
> +	it6505_aux_termination_on(it6505);
> +}
> +
> +static void it6505_aux_reset(struct it6505 *it6505)
> +{
> +	it6505_set_bits(it6505, REG_RESET_CTRL, AUX_RESET, AUX_RESET);
> +	it6505_set_bits(it6505, REG_RESET_CTRL, AUX_RESET, 0x00);
> +}
> +
> +static void it6505_reset_logic(struct it6505 *it6505)
> +{
> +	regmap_write(it6505->regmap, REG_RESET_CTRL, ALL_LOGIC_RESET);
> +	usleep_range(1000, 1500);
> +}
> +
> +static bool it6505_aux_op_finished(struct it6505 *it6505)
> +{
> +	int reg2b = it6505_read(it6505, REG_AUX_CMD_REQ);
> +
> +	if (reg2b < 0)
> +		return false;
> +
> +	return (reg2b & AUX_BUSY) == 0;
> +}
> +
> +static int it6505_aux_wait(struct it6505 *it6505)
> +{
> +	int status;
> +	unsigned long timeout;
> +	struct device *dev = &it6505->client->dev;
> +
> +	timeout = jiffies + msecs_to_jiffies(AUX_WAIT_TIMEOUT_MS) + 1;
> +
> +	while (!it6505_aux_op_finished(it6505)) {
> +		if (time_after(jiffies, timeout)) {
> +			DRM_DEV_ERROR(dev, "Timed out waiting AUX to finish");
> +			return -ETIMEDOUT;
> +		}
> +		usleep_range(1000, 2000);
> +	}
> +
> +	status = it6505_read(it6505, REG_AUX_ERROR_STS);
> +	if (status < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to read AUX channel: %d", status);
> +		return status;
> +	}
> +
> +	return 0;
> +}
> +
> +static ssize_t it6505_aux_operation(struct it6505 *it6505,
> +				    enum aux_cmd_type cmd,
> +				    unsigned int address, u8 *buffer,
> +				    size_t size, enum aux_cmd_reply *reply)
> +{
> +	int i, ret;
> +	bool aux_write_check = false;
> +
> +	if (!it6505_get_sink_hpd_status(it6505))
> +		return -EIO;
> +
> +	/* set AUX user mode */
> +	it6505_set_bits(it6505, REG_AUX_CTRL, AUX_USER_MODE, AUX_USER_MODE);
> +
> +aux_op_start:
> +	if (cmd == CMD_AUX_I2C_EDID_READ) {
> +		/* AUX EDID FIFO has max length of AUX_FIFO_MAX_SIZE bytes. */
> +		size = min_t(size_t, size, AUX_FIFO_MAX_SIZE);
> +		/* Enable AUX FIFO read back and clear FIFO */
> +		it6505_set_bits(it6505, REG_AUX_CTRL,
> +				AUX_EN_FIFO_READ | CLR_EDID_FIFO,
> +				AUX_EN_FIFO_READ | CLR_EDID_FIFO);
> +
> +		it6505_set_bits(it6505, REG_AUX_CTRL,
> +				AUX_EN_FIFO_READ | CLR_EDID_FIFO,
> +				AUX_EN_FIFO_READ);
> +	} else {
> +		/* The DP AUX transmit buffer has 4 bytes. */
> +		size = min_t(size_t, size, 4);
> +		it6505_set_bits(it6505, REG_AUX_CTRL, AUX_NO_SEGMENT_WR,
> +				AUX_NO_SEGMENT_WR);
> +	}
> +
> +	/* Start Address[7:0] */
> +	it6505_write(it6505, REG_AUX_ADR_0_7, (address >> 0) & 0xFF);
> +	/* Start Address[15:8] */
> +	it6505_write(it6505, REG_AUX_ADR_8_15, (address >> 8) & 0xFF);
> +	/* WriteNum[3:0]+StartAdr[19:16] */
> +	it6505_write(it6505, REG_AUX_ADR_16_19,
> +		     ((address >> 16) & 0x0F) | ((size - 1) << 4));
> +
> +	if (cmd == CMD_AUX_NATIVE_WRITE)
> +		regmap_bulk_write(it6505->regmap, REG_AUX_OUT_DATA0, buffer,
> +				  size);
> +
> +	/* Aux Fire */
> +	it6505_write(it6505, REG_AUX_CMD_REQ, cmd);
> +
> +	ret = it6505_aux_wait(it6505);
> +	if (ret < 0)
> +		goto aux_op_err;
> +
> +	ret = it6505_read(it6505, REG_AUX_ERROR_STS);
> +	if (ret < 0)
> +		goto aux_op_err;
> +
> +	switch ((ret >> 6) & 0x3) {
> +	case 0:
> +		*reply = REPLY_ACK;
> +		break;
> +	case 1:
> +		*reply = REPLY_DEFER;
> +		ret = -EAGAIN;
> +		goto aux_op_err;
> +	case 2:
> +		*reply = REPLY_NACK;
> +		ret = -EIO;
> +		goto aux_op_err;
> +	case 3:
> +		ret = -ETIMEDOUT;
> +		goto aux_op_err;
> +	}
> +
> +	/* Read back Native Write data */
> +	if (cmd == CMD_AUX_NATIVE_WRITE) {
> +		aux_write_check = true;
> +		cmd = CMD_AUX_NATIVE_READ;
> +		goto aux_op_start;
> +	}
> +
> +	if (cmd == CMD_AUX_I2C_EDID_READ) {
> +		for (i = 0; i < size; i++) {
> +			ret = it6505_read(it6505, REG_AUX_DATA_FIFO);
> +			if (ret < 0)
> +				goto aux_op_err;
> +			buffer[i] = ret;
> +		}
> +	} else {
> +		for (i = 0; i < size; i++) {
> +			ret = it6505_read(it6505, REG_AUX_DATA_0_7 + i);
> +			if (ret < 0)
> +				goto aux_op_err;
> +
> +			if (aux_write_check && buffer[size - 1 - i] != ret) {
> +				ret = -EINVAL;
> +				goto aux_op_err;
> +			}
> +
> +			buffer[size - 1 - i] = ret;
> +		}
> +	}
> +
> +	ret = i;
> +
> +aux_op_err:
> +	if (cmd == CMD_AUX_I2C_EDID_READ) {
> +		/* clear AUX FIFO */
> +		it6505_set_bits(it6505, REG_AUX_CTRL,
> +				AUX_EN_FIFO_READ | CLR_EDID_FIFO,
> +				AUX_EN_FIFO_READ | CLR_EDID_FIFO);
> +		it6505_set_bits(it6505, REG_AUX_CTRL,
> +				AUX_EN_FIFO_READ | CLR_EDID_FIFO, 0x00);
> +	}
> +
> +	/* Leave AUX user mode */
> +	it6505_set_bits(it6505, REG_AUX_CTRL, AUX_USER_MODE, 0);
> +
> +	return ret;
> +}
> +
> +static ssize_t it6505_aux_do_transfer(struct it6505 *it6505,
> +				      enum aux_cmd_type cmd,
> +				      unsigned int address, u8 *buffer,
> +				      size_t size, enum aux_cmd_reply *reply)
> +{
> +	int i, ret_size, ret = 0, request_size;
> +
> +	mutex_lock(&it6505->aux_lock);
> +	for (i = 0; i < size; i += 4) {
> +		request_size = min((int)size - i, 4);
> +		ret_size = it6505_aux_operation(it6505, cmd, address + i,
> +						buffer + i, request_size,
> +						reply);
> +		if (ret_size < 0) {
> +			ret = ret_size;
> +			goto aux_op_err;
> +		}
> +
> +		ret += ret_size;
> +	}
> +
> +aux_op_err:
> +	mutex_unlock(&it6505->aux_lock);
> +	return ret;
> +}
> +
> +static ssize_t it6505_aux_transfer(struct drm_dp_aux *aux,
> +				   struct drm_dp_aux_msg *msg)
> +{
> +	struct it6505 *it6505 = container_of(aux, struct it6505, aux);
> +	u8 cmd;
> +	bool is_i2c = !(msg->request & DP_AUX_NATIVE_WRITE);
> +	int ret;
> +	enum aux_cmd_reply reply;
> +
> +	/* IT6505 doesn't support arbitrary I2C read / write. */
> +	if (is_i2c)
> +		return -EINVAL;
> +
> +	switch (msg->request) {
> +	case DP_AUX_NATIVE_READ:
> +		cmd = CMD_AUX_NATIVE_READ;
> +		break;
> +	case DP_AUX_NATIVE_WRITE:
> +		cmd = CMD_AUX_NATIVE_WRITE;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	ret = it6505_aux_do_transfer(it6505, cmd, msg->address, msg->buffer,
> +				     msg->size, &reply);
> +	if (ret < 0)
> +		return ret;
> +
> +	switch (reply) {
> +	case REPLY_ACK:
> +		msg->reply = DP_AUX_NATIVE_REPLY_ACK;
> +		break;
> +	case REPLY_NACK:
> +		msg->reply = DP_AUX_NATIVE_REPLY_NACK;
> +		break;
> +	case REPLY_DEFER:
> +		msg->reply = DP_AUX_NATIVE_REPLY_DEFER;
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
> +static int it6505_get_edid_block(void *data, u8 *buf, unsigned int block,
> +				 size_t len)
> +{
> +	struct it6505 *it6505 = data;
> +	struct device *dev = &it6505->client->dev;
> +	enum aux_cmd_reply reply;
> +	int offset, ret, aux_retry = 100;
> +
> +	it6505_aux_reset(it6505);
> +	DRM_DEV_DEBUG_DRIVER(dev, "block number = %d", block);
> +
> +	for (offset = 0; offset < EDID_LENGTH;) {
> +		ret = it6505_aux_do_transfer(it6505, CMD_AUX_I2C_EDID_READ,
> +					     block * EDID_LENGTH + offset,
> +					     buf + offset, 8, &reply);
> +
> +		if (ret < 0 && ret != -EAGAIN)
> +			return ret;
> +
> +		switch (reply) {
> +		case REPLY_ACK:
> +			DRM_DEV_DEBUG_DRIVER(dev, "[0x%02x]: %8ph", offset,
> +					     buf + offset);
> +			offset += 8;
> +			aux_retry = 100;
> +			break;
> +		case REPLY_NACK:
> +			return -EIO;
> +		case REPLY_DEFER:
> +			msleep(20);
> +			if (!(--aux_retry))
> +				return -EIO;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static void it6505_variable_config(struct it6505 *it6505)
> +{
> +	it6505->link_rate_bw_code = HBR;
> +	it6505->lane_count = MAX_LANE_COUNT;
> +	it6505->link_state = LINK_IDLE;
> +	it6505->hdcp_desired = HDCP_DESIRED;
> +	it6505->auto_train_retry = AUTO_TRAIN_RETRY;
> +	it6505->audio.select = AUDIO_SELECT;
> +	it6505->audio.sample_rate = AUDIO_SAMPLE_RATE;
> +	it6505->audio.channel_count = AUDIO_CHANNEL_COUNT;
> +	it6505->audio.type = AUDIO_TYPE;
> +	it6505->audio.i2s_input_format = I2S_INPUT_FORMAT;
> +	it6505->audio.i2s_justified = I2S_JUSTIFIED;
> +	it6505->audio.i2s_data_delay = I2S_DATA_DELAY;
> +	it6505->audio.i2s_ws_channel = I2S_WS_CHANNEL;
> +	it6505->audio.i2s_data_sequence = I2S_DATA_SEQUENCE;
> +	it6505->audio.word_length = AUDIO_WORD_LENGTH;
> +	memset(it6505->sha1_input, 0, sizeof(it6505->sha1_input));
> +	memset(it6505->bksvs, 0, sizeof(it6505->bksvs));
> +}
> +
> +static int it6505_send_video_infoframe(struct it6505 *it6505,
> +				       struct hdmi_avi_infoframe *frame)
> +{
> +	u8 buffer[HDMI_INFOFRAME_HEADER_SIZE + HDMI_AVI_INFOFRAME_SIZE];
> +	int err;
> +	struct device *dev = &it6505->client->dev;
> +
> +	err = hdmi_avi_infoframe_pack(frame, buffer, sizeof(buffer));
> +	if (err < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to pack AVI infoframe: %d", err);
> +		return err;
> +	}
> +
> +	err = it6505_set_bits(it6505, REG_INFOFRAME_CTRL, EN_AVI_PKT, 0x00);
> +	if (err)
> +		return err;
> +
> +	err = regmap_bulk_write(it6505->regmap, REG_AVI_INFO_DB1,
> +				buffer + HDMI_INFOFRAME_HEADER_SIZE,
> +				frame->length);
> +	if (err)
> +		return err;
> +
> +	err = it6505_set_bits(it6505, REG_INFOFRAME_CTRL, EN_AVI_PKT,
> +			      EN_AVI_PKT);
> +	if (err)
> +		return err;
> +
> +	return 0;
> +}
> +
> +static void it6505_get_extcon_property(struct it6505 *it6505)
> +{
> +	int err;
> +	union extcon_property_value property;
> +	struct device *dev = &it6505->client->dev;
> +
> +	if (it6505->extcon && !it6505->lane_swap_disabled) {
> +		err = extcon_get_property(it6505->extcon, EXTCON_DISP_DP,
> +					  EXTCON_PROP_USB_TYPEC_POLARITY,
> +					  &property);
> +		if (err) {
> +			DRM_DEV_ERROR(dev, "get property fail!");
> +			return;
> +		}
> +		it6505->lane_swap = property.intval;
> +	}
> +}
> +
> +static void it6505_clk_phase_adjustment(struct it6505 *it6505,
> +					const struct drm_display_mode *mode)
> +{
> +	it6505_set_bits(it6505, REG_CLK_CTRL0, M_PCLK_DELAY,
> +		mode->clock < ADJUST_PHASE_THRESHOLD ? PIXEL_CLK_DELAY : 0);
> +	it6505_set_bits(it6505, REG_DATA_CTRL0, VIDEO_LATCH_EDGE,
> +			PIXEL_CLK_INVERSE << 4);
> +}
> +
> +static void it6505_init(struct it6505 *it6505)
> +{
> +	it6505_write(it6505, REG_BANK_SEL, 0x00);
> +	it6505_write(it6505, REG_AUX_OPT, AUX_AUTO_RST | AUX_FIX_FREQ);
> +	it6505_write(it6505, REG_AUX_CTRL, AUX_NO_SEGMENT_WR);
> +	it6505_write(it6505, REG_HDCP_CTRL2, HDCP_AN_SEL | HDCP_HW_HPDIRQ_ACT);
> +	it6505_write(it6505, REG_VID_BUS_CTRL0, IN_DDR | DDR_CD);
> +	it6505_write(it6505, REG_VID_BUS_CTRL1, 0x01);
> +	it6505_write(it6505, REG_AUDIO_CTRL0, AUDIO_16B_BOUND);
> +
> +	/* chip internal setting, don't modify */
> +	it6505_write(it6505, REG_HPD_IRQ_TIME, 0xF5);
> +	it6505_write(it6505, REG_AUX_DEBUG_MODE, 0x4D);
> +	it6505_write(it6505, REG_AUX_OPT2, 0x17);
> +	it6505_write(it6505, REG_HDCP_OPT, 0x60);
> +	it6505_write(it6505, REG_DATA_MUTE_CTRL,
> +		     EN_VID_MUTE | EN_AUD_MUTE | ENABLE_AUTO_VIDEO_FIFO_RESET);
> +	it6505_write(it6505, REG_TIME_STMP_CTRL,
> +		     EN_SSC_GAT | EN_ENHANCE_VID_STMP | EN_ENHANCE_AUD_STMP);
> +	it6505_write(it6505, REG_INFOFRAME_CTRL, 0x00);
> +	it6505_write(it6505, REG_BANK_SEL, 0x01);
> +	it6505_write(it6505, REG_DRV_0_DB_800_MV,
> +		     afe_setting_table[it6505->afe_setting][0]);
> +	it6505_write(it6505, REG_PRE_0_DB_800_MV,
> +		     afe_setting_table[it6505->afe_setting][1]);
> +	it6505_write(it6505, REG_PRE_3P5_DB_800_MV,
> +		     afe_setting_table[it6505->afe_setting][2]);
> +	it6505_write(it6505, REG_SSC_CTRL0, 0x9E);
> +	it6505_write(it6505, REG_SSC_CTRL1, 0x1C);
> +	it6505_write(it6505, REG_SSC_CTRL2, 0x42);
> +	it6505_write(it6505, REG_BANK_SEL, 0x00);
> +}
> +
> +static void it6505_video_disable(struct it6505 *it6505)
> +{
> +	it6505_set_bits(it6505, REG_DATA_MUTE_CTRL, EN_VID_MUTE, EN_VID_MUTE);
> +	it6505_set_bits(it6505, REG_INFOFRAME_CTRL, EN_VID_CTRL_PKT, 0x00);
> +	it6505_set_bits(it6505, REG_RESET_CTRL, VIDEO_RESET, VIDEO_RESET);
> +}
> +
> +static void it6505_video_reset(struct it6505 *it6505)
> +{
> +	it6505_set_bits(it6505, REG_DATA_MUTE_CTRL, EN_VID_MUTE, EN_VID_MUTE);
> +	it6505_set_bits(it6505, REG_INFOFRAME_CTRL, EN_VID_CTRL_PKT, 0x00);
> +	it6505_set_bits(it6505, REG_RESET_CTRL, VIDEO_RESET, VIDEO_RESET);
> +	it6505_set_bits(it6505, REG_501_FIFO_CTRL, RST_501_FIFO, RST_501_FIFO);
> +	it6505_set_bits(it6505, REG_501_FIFO_CTRL, RST_501_FIFO, 0x00);
> +	it6505_set_bits(it6505, REG_RESET_CTRL, VIDEO_RESET, 0x00);
> +}
> +
> +static void it6505_update_video_parameter(struct it6505 *it6505,
> +					  const struct drm_display_mode *mode)
> +{
> +	it6505_clk_phase_adjustment(it6505, mode);
> +	it6505_video_disable(it6505);
> +}
> +
> +static bool it6505_audio_input(struct it6505 *it6505)
> +{
> +	int reg05, regbe;
> +
> +	reg05 = it6505_read(it6505, REG_RESET_CTRL);
> +	it6505_set_bits(it6505, REG_RESET_CTRL, AUDIO_RESET, 0x00);
> +	usleep_range(3000, 4000);
> +	regbe = it6505_read(it6505, REG_AUDIO_INPUT_FREQ);
> +	it6505_write(it6505, REG_RESET_CTRL, reg05);
> +
> +	return regbe != 0xFF;
> +}
> +
> +static void it6505_setup_audio_channel_status(struct it6505 *it6505)
> +{
> +	enum it6505_audio_sample_rate sample_rate = it6505->audio.sample_rate;
> +	u8 audio_word_length_map[] = { 0x02, 0x04, 0x03, 0x0B };
> +
> +	/* Channel Status */
> +	it6505_write(it6505, REG_IEC958_STS0, it6505->audio.type << 1);
> +	it6505_write(it6505, REG_IEC958_STS1, 0x00);
> +	it6505_write(it6505, REG_IEC958_STS2, 0x00);
> +	it6505_write(it6505, REG_IEC958_STS3, sample_rate);
> +	it6505_write(it6505, REG_IEC958_STS4, (~sample_rate << 4) |
> +		     audio_word_length_map[it6505->audio.word_length]);
> +}
> +
> +static void it6505_setup_audio_format(struct it6505 *it6505)
> +{
> +	/* I2S MODE */
> +	it6505_write(it6505, REG_AUDIO_FMT,
> +		     (it6505->audio.word_length << 5) |
> +		     (it6505->audio.i2s_data_sequence << 4) |
> +		     (it6505->audio.i2s_ws_channel << 3) |
> +		     (it6505->audio.i2s_data_delay << 2) |
> +		     (it6505->audio.i2s_justified << 1) |
> +		     it6505->audio.i2s_input_format);
> +	if (it6505->audio.select == SPDIF) {
> +		it6505_write(it6505, REG_AUDIO_FIFO_SEL, 0x00);
> +		/* 0x30 = 128*FS */
> +		it6505_set_bits(it6505, REG_AUX_OPT, 0xF0, 0x30);
> +	} else {
> +		it6505_write(it6505, REG_AUDIO_FIFO_SEL, 0xE4);
> +	}
> +
> +	it6505_write(it6505, REG_AUDIO_CTRL0, 0x20);
> +	it6505_write(it6505, REG_AUDIO_CTRL1, 0x00);
> +}
> +
> +static void it6505_enable_audio_source(struct it6505 *it6505)
> +{
> +	unsigned int audio_source_count;
> +
> +	audio_source_count = BIT(DIV_ROUND_UP(it6505->audio.channel_count, 2))
> +				 - 1;
> +
> +	audio_source_count |= it6505->audio.select << 4;
> +
> +	it6505_write(it6505, REG_AUDIO_SRC_CTRL, audio_source_count);
> +}
> +
> +static void it6505_enable_audio_infoframe(struct it6505 *it6505)
> +{
> +	struct device *dev = &it6505->client->dev;
> +	u8 audio_info_ca[] = { 0x00, 0x00, 0x01, 0x03, 0x07, 0x0B, 0x0F, 0x1F };
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "infoframe channel_allocation:0x%02x",
> +			     audio_info_ca[it6505->audio.channel_count - 1]);
> +
> +	it6505_write(it6505, REG_AUD_INFOFRAM_DB1, it6505->audio.channel_count
> +		     - 1);
> +	it6505_write(it6505, REG_AUD_INFOFRAM_DB2, 0x00);
> +	it6505_write(it6505, REG_AUD_INFOFRAM_DB3,
> +		     audio_info_ca[it6505->audio.channel_count - 1]);
> +	it6505_write(it6505, REG_AUD_INFOFRAM_DB4, 0x00);
> +	it6505_write(it6505, REG_AUD_INFOFRAM_SUM, 0x00);
> +
> +	/* Enable Audio InfoFrame */
> +	it6505_set_bits(it6505, REG_INFOFRAME_CTRL, EN_AUD_CTRL_PKT,
> +			EN_AUD_CTRL_PKT);
> +}
> +
> +static void it6505_disable_audio(struct it6505 *it6505)
> +{
> +	it6505_set_bits(it6505, REG_DATA_MUTE_CTRL, EN_AUD_MUTE, EN_AUD_MUTE);
> +	it6505_set_bits(it6505, REG_AUDIO_SRC_CTRL, M_AUDIO_I2S_EN, 0x00);
> +	it6505_set_bits(it6505, REG_INFOFRAME_CTRL, EN_AUD_CTRL_PKT, 0x00);
> +	it6505_set_bits(it6505, REG_RESET_CTRL, AUDIO_RESET, AUDIO_RESET);
> +}
> +
> +static void it6505_enable_audio(struct it6505 *it6505)
> +{
> +	struct device *dev = &it6505->client->dev;
> +	int regbe;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "start");
> +	it6505_disable_audio(it6505);
> +
> +	it6505_setup_audio_channel_status(it6505);
> +	it6505_setup_audio_format(it6505);
> +	it6505_enable_audio_source(it6505);
> +	it6505_enable_audio_infoframe(it6505);
> +
> +	it6505_write(it6505, REG_AUDIO_N_0_7, 0x00);
> +	it6505_write(it6505, REG_AUDIO_N_8_15, 0x80);
> +	it6505_write(it6505, REG_AUDIO_N_16_23, 0x00);
> +
> +	it6505_set_bits(it6505, REG_AUDIO_SRC_CTRL, AUDIO_FIFO_RESET,
> +			AUDIO_FIFO_RESET);
> +	it6505_set_bits(it6505, REG_AUDIO_SRC_CTRL, AUDIO_FIFO_RESET, 0x00);
> +	it6505_set_bits(it6505, REG_RESET_CTRL, AUDIO_RESET, 0x00);
> +	regbe = it6505_read(it6505, REG_AUDIO_INPUT_FREQ);
> +	DRM_DEV_DEBUG_DRIVER(dev, "regbe:0x%02x audio input fs: %d.%d kHz",
> +			     regbe, 6750 / regbe, (6750 % regbe) * 10 / regbe);
> +	it6505_set_bits(it6505, REG_DATA_MUTE_CTRL, EN_AUD_MUTE, 0x00);
> +}
> +
> +static bool it6505_use_step_train_check(struct it6505 *it6505)
> +{
> +	if (it6505->link.revision >= 0x12)
> +		return it6505->dpcd[DP_TRAINING_AUX_RD_INTERVAL] >= 0x01;
> +
> +	return true;
> +}
> +
> +static void it6505_parse_link_capabilities(struct it6505 *it6505)
> +{
> +	struct device *dev = &it6505->client->dev;
> +	struct it6505_drm_dp_link *link = &it6505->link;
> +	int bcaps;
> +
> +	if (it6505->dpcd[0] == 0) {
> +		it6505_aux_on(it6505);
> +		it6505_get_dpcd(it6505, DP_DPCD_REV, it6505->dpcd,
> +				ARRAY_SIZE(it6505->dpcd));
> +	}
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "DPCD Rev.: %d.%d",
> +			     link->revision >> 4, link->revision & 0x0F);
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "Sink max link rate: %d.%02d Gbps per lane",
> +			     link->rate / 100000, link->rate / 1000 % 100);
> +
> +	it6505->link_rate_bw_code = drm_dp_link_rate_to_bw_code(link->rate);
> +	DRM_DEV_DEBUG_DRIVER(dev, "link rate bw code:0x%02x",
> +			     it6505->link_rate_bw_code);
> +	it6505->link_rate_bw_code = min((int)it6505->link_rate_bw_code,
> +					MAX_LINK_RATE);
> +
> +	it6505->lane_count = link->num_lanes;
> +	DRM_DEV_DEBUG_DRIVER(dev, "Sink support %d lanes training",
> +			     it6505->lane_count);
> +	it6505->lane_count = min((int)it6505->lane_count, MAX_LANE_COUNT);
> +
> +	it6505->branch_device = drm_dp_is_branch(it6505->dpcd);
> +	DRM_DEV_DEBUG_DRIVER(dev, "Sink %sbranch device",
> +			     it6505->branch_device ? "" : "Not ");
> +
> +	it6505->enable_enhanced_frame = !!link->capabilities;
> +	DRM_DEV_DEBUG_DRIVER(dev, "Sink %sSupport Enhanced Framing",
> +			     it6505->enable_enhanced_frame ? "" : "Not ");
> +
> +	it6505->enable_ssc = !!(it6505->dpcd[DP_MAX_DOWNSPREAD] &
> +				DP_MAX_DOWNSPREAD_0_5);
> +	DRM_DEV_DEBUG_DRIVER(dev, "Maximum Down-Spread: %s, %ssupport SSC!",
> +			     it6505->enable_ssc ? "0.5" : "0",
> +			     it6505->enable_ssc ? "" : "Not ");
> +
> +	it6505->step_train = it6505_use_step_train_check(it6505);
> +	if (it6505->step_train)
> +		DRM_DEV_DEBUG_DRIVER(dev, "auto train fail, will step train");
> +
> +	bcaps = it6505_dpcd_read(it6505, DP_AUX_HDCP_BCAPS);
> +	DRM_DEV_DEBUG_DRIVER(dev, "bcaps:0x%02x", bcaps);
> +	if (bcaps & DP_BCAPS_HDCP_CAPABLE) {
> +		it6505->is_repeater = !!(bcaps & DP_BCAPS_REPEATER_PRESENT);
> +		DRM_DEV_DEBUG_DRIVER(dev, "Support HDCP! Downstream is %s!",
> +				     it6505->is_repeater ? "repeater" :
> +				     "receiver");
> +	} else {
> +		DRM_DEV_DEBUG_DRIVER(dev, "Sink not support HDCP!");
> +		it6505->hdcp_desired = false;
> +	}
> +	DRM_DEV_DEBUG_DRIVER(dev, "HDCP %s",
> +			     it6505->hdcp_desired ? "desired" : "undesired");
> +}
> +
> +static void it6505_setup_ssc(struct it6505 *it6505)
> +{
> +	it6505_set_bits(it6505, REG_TRAIN_CTRL0, SPREAD_AMP_5,
> +			it6505->enable_ssc ? SPREAD_AMP_5 : 0x00);
> +	if (it6505->enable_ssc) {
> +		it6505_write(it6505, REG_BANK_SEL, 0x01);
> +		it6505_write(it6505, REG_SSC_CTRL0, 0x9E);
> +		it6505_write(it6505, REG_SSC_CTRL1, 0x1C);
> +		it6505_write(it6505, REG_SSC_CTRL2, 0x42);
> +		it6505_write(it6505, REG_BANK_SEL, 0x00);
> +		it6505_write(it6505, REG_SP_CTRL0, 0x07);
> +		it6505_write(it6505, REG_IP_CTRL1, 0x29);
> +		it6505_write(it6505, REG_IP_CTRL2, 0x03);
> +		/* Stamp Interrupt Step */
> +		it6505_set_bits(it6505, REG_TIME_STMP_CTRL, M_STAMP_STEP,
> +				0x10);
> +		it6505_dpcd_write(it6505, DP_DOWNSPREAD_CTRL,
> +				  DP_SPREAD_AMP_0_5);
> +	} else {
> +		it6505_dpcd_write(it6505, DP_DOWNSPREAD_CTRL, 0x00);
> +		it6505_set_bits(it6505, REG_TIME_STMP_CTRL, M_STAMP_STEP,
> +				0x00);
> +	}
> +}
> +
> +static inline void it6505_link_rate_setup(struct it6505 *it6505)
> +{
> +	it6505_set_bits(it6505, REG_TRAIN_CTRL0, FORCE_LBR,
> +			(it6505->link_rate_bw_code == RBR) ? FORCE_LBR : 0x00);
> +	it6505_set_bits(it6505, REG_LINK_DRV, DRV_HS,
> +			(it6505->link_rate_bw_code == RBR) ? 0x00 : DRV_HS);
> +}
> +
> +static void it6505_lane_count_setup(struct it6505 *it6505)
> +{
> +	it6505_get_extcon_property(it6505);
> +	it6505_set_bits(it6505, REG_TRAIN_CTRL0, LANE_SWAP,
> +			it6505->lane_swap ? LANE_SWAP : 0x00);
> +	it6505_set_bits(it6505, REG_TRAIN_CTRL0, LANE_COUNT_MASK,
> +			(it6505->lane_count - 1) << 1);
> +}
> +
> +static void it6505_link_training_setup(struct it6505 *it6505)
> +{
> +	struct device *dev = &it6505->client->dev;
> +
> +	if (it6505->enable_enhanced_frame)
> +		it6505_set_bits(it6505, REG_DATA_MUTE_CTRL,
> +				ENABLE_ENHANCED_FRAME, ENABLE_ENHANCED_FRAME);
> +
> +	it6505_link_rate_setup(it6505);
> +	it6505_lane_count_setup(it6505);
> +	it6505_setup_ssc(it6505);
> +	DRM_DEV_DEBUG_DRIVER(dev,
> +			     "%s, %d lanes, %sable ssc, %sable enhanced frame",
> +			     it6505->link_rate_bw_code != RBR ? "HBR" : "RBR",
> +			     it6505->lane_count,
> +			     it6505->enable_ssc ? "en" : "dis",
> +			     it6505->enable_enhanced_frame ? "en" : "dis");
> +}
> +
> +static bool it6505_link_start_auto_train(struct it6505 *it6505)
> +{
> +	int timeout = 500, link_training_state;
> +	bool state = false;
> +
> +	mutex_lock(&it6505->aux_lock);
> +	it6505_set_bits(it6505, REG_TRAIN_CTRL0,
> +				FORCE_CR_DONE | FORCE_EQ_DONE, 0x00);
> +	it6505_write(it6505, REG_TRAIN_CTRL1, FORCE_RETRAIN);
> +	it6505_write(it6505, REG_TRAIN_CTRL1, AUTO_TRAIN);
> +
> +	while (timeout > 0) {
> +		usleep_range(1000, 2000);
> +		link_training_state = it6505_read(it6505, REG_LINK_TRAIN_STS);
> +
> +		if ((link_training_state > 0) &&
> +		    (link_training_state & LINK_STATE_NORP)) {
> +			state = true;
> +			goto unlock;
> +		}
> +
> +		timeout--;
> +	}
> +unlock:
> +	mutex_unlock(&it6505->aux_lock);
> +
> +	return state;
> +}
> +
> +static int it6505_drm_dp_link_configure(struct it6505 *it6505)
> +{
> +	u8 values[2];
> +	int err;
> +	struct drm_dp_aux *aux = &it6505->aux;
> +
> +	values[0] = it6505->link_rate_bw_code;
> +	values[1] = it6505->lane_count;
> +
> +	if (it6505->enable_enhanced_frame)
> +		values[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
> +
> +	err = drm_dp_dpcd_write(aux, DP_LINK_BW_SET, values, sizeof(values));
> +	if (err < 0)
> +		return err;
> +
> +	return 0;
> +}
> +
> +static bool it6505_check_voltage_swing_max(u8 lane_voltage_swing_pre_emphasis)
> +{
> +	return ((lane_voltage_swing_pre_emphasis & 0x03) == MAX_CR_LEVEL);
> +}
> +
> +static bool it6505_check_pre_emphasis_max(u8 lane_voltage_swing_pre_emphasis)
> +{
> +	return ((lane_voltage_swing_pre_emphasis & 0x03) == MAX_EQ_LEVEL);
> +}
> +
> +static bool it6505_check_max_voltage_swing_reached(u8 *lane_voltage_swing,
> +						   u8 lane_count)
> +{
> +	u8 i;
> +
> +	for (i = 0; i < lane_count; i++) {
> +		if (lane_voltage_swing[i] & DP_TRAIN_MAX_SWING_REACHED)
> +			return true;
> +	}
> +
> +	return false;
> +}
> +
> +static bool it6505_step_train_lane_voltage_pre_emphasis_set(
> +	struct it6505 *it6505,
> +	struct it6505_step_train_para *lane_voltage_pre_emphasis,
> +	u8 *lane_voltage_pre_emphasis_set)
> +{
> +	u8 i;
> +
> +	for (i = 0; i < it6505->lane_count; i++) {
> +		lane_voltage_pre_emphasis->voltage_swing[i] &= 0x03;
> +		lane_voltage_pre_emphasis_set[i] =
> +			lane_voltage_pre_emphasis->voltage_swing[i];
> +		if (it6505_check_voltage_swing_max(
> +			    lane_voltage_pre_emphasis->voltage_swing[i]))
> +			lane_voltage_pre_emphasis_set[i] |=
> +				DP_TRAIN_MAX_SWING_REACHED;
> +
> +		lane_voltage_pre_emphasis->pre_emphasis[i] &= 0x03;
> +		lane_voltage_pre_emphasis_set[i] |=
> +			lane_voltage_pre_emphasis->pre_emphasis[i]
> +			<< DP_TRAIN_PRE_EMPHASIS_SHIFT;
> +		if (it6505_check_pre_emphasis_max(
> +			    lane_voltage_pre_emphasis->pre_emphasis[i]))
> +			lane_voltage_pre_emphasis_set[i] |=
> +				DP_TRAIN_MAX_PRE_EMPHASIS_REACHED;
> +		it6505_dpcd_write(it6505, DP_TRAINING_LANE0_SET + i,
> +				  lane_voltage_pre_emphasis_set[i]);
> +
> +		if (lane_voltage_pre_emphasis_set[i] !=
> +		    it6505_dpcd_read(it6505, DP_TRAINING_LANE0_SET + i))
> +			return false;
> +	}
> +
> +	return true;
> +}
> +
> +static bool
> +it6505_step_cr_train(struct it6505 *it6505,
> +		     struct it6505_step_train_para *lane_voltage_pre_emphasis)
> +{
> +	u8 loop_count = 0, i = 0, j;
> +	u8 link_status[DP_LINK_STATUS_SIZE] = { 0 };
> +	u8 lane_level_config[MAX_LANE_COUNT] = { 0 };
> +	int pre_emphasis_adjust = -1, voltage_swing_adjust = -1;
> +
> +	it6505_dpcd_write(it6505, DP_DOWNSPREAD_CTRL,
> +			  it6505->enable_ssc ? DP_SPREAD_AMP_0_5 : 0x00);
> +	it6505_dpcd_write(it6505, DP_TRAINING_PATTERN_SET,
> +			  DP_TRAINING_PATTERN_1);
> +
> +	while (loop_count < 5 && i < 10) {
> +		i++;
> +		if (!it6505_step_train_lane_voltage_pre_emphasis_set(
> +			    it6505, lane_voltage_pre_emphasis,
> +			    lane_level_config))
> +			continue;
> +		drm_dp_link_train_clock_recovery_delay(it6505->dpcd);
> +		drm_dp_dpcd_read_link_status(&it6505->aux, link_status);
> +
> +		if (drm_dp_clock_recovery_ok(link_status, it6505->lane_count)) {
> +			it6505_set_bits(it6505, REG_TRAIN_CTRL0, FORCE_CR_DONE,
> +					FORCE_CR_DONE);
> +			return true;
> +		}
> +		DRM_DEV_DEBUG_DRIVER(&it6505->client->dev, "cr not done");
> +
> +		if (it6505_check_max_voltage_swing_reached(lane_level_config,
> +							   it6505->lane_count))
> +			goto cr_train_fail;
> +
> +		for (j = 0; j < it6505->lane_count; j++) {
> +			lane_voltage_pre_emphasis->voltage_swing[j] =
> +				drm_dp_get_adjust_request_voltage(link_status,
> +								  j) >>
> +				DP_TRAIN_VOLTAGE_SWING_SHIFT;
> +			lane_voltage_pre_emphasis->pre_emphasis[j] =
> +				drm_dp_get_adjust_request_pre_emphasis(
> +					link_status, j) >>
> +				DP_TRAIN_PRE_EMPHASIS_SHIFT;
> +			if ((voltage_swing_adjust ==
> +			     lane_voltage_pre_emphasis->voltage_swing[j]) &&
> +			    (pre_emphasis_adjust ==
> +			     lane_voltage_pre_emphasis->pre_emphasis[j])) {
> +				loop_count++;
> +				continue;
> +			}
> +
> +			voltage_swing_adjust =
> +				lane_voltage_pre_emphasis->voltage_swing[j];
> +			pre_emphasis_adjust =
> +				lane_voltage_pre_emphasis->pre_emphasis[j];
> +			loop_count = 0;
> +
> +			if (voltage_swing_adjust + pre_emphasis_adjust >
> +			    MAX_EQ_LEVEL)
> +				lane_voltage_pre_emphasis->voltage_swing[j] =
> +					MAX_EQ_LEVEL -
> +					lane_voltage_pre_emphasis
> +						->pre_emphasis[j];
> +		}
> +	}
> +
> +cr_train_fail:
> +	it6505_dpcd_write(it6505, DP_TRAINING_PATTERN_SET,
> +			  DP_TRAINING_PATTERN_DISABLE);
> +
> +	return false;
> +}
> +
> +static bool
> +it6505_step_eq_train(struct it6505 *it6505,
> +		     struct it6505_step_train_para *lane_voltage_pre_emphasis)
> +{
> +	u8 loop_count = 0, i, link_status[DP_LINK_STATUS_SIZE] = { 0 };
> +	u8 lane_level_config[MAX_LANE_COUNT] = { 0 };
> +
> +	it6505_dpcd_write(it6505, DP_TRAINING_PATTERN_SET,
> +			  DP_TRAINING_PATTERN_2);
> +
> +	while (loop_count < 6) {
> +		loop_count++;
> +
> +		if (!it6505_step_train_lane_voltage_pre_emphasis_set(
> +			    it6505, lane_voltage_pre_emphasis,
> +			    lane_level_config))
> +			continue;
> +
> +		drm_dp_link_train_channel_eq_delay(it6505->dpcd);
> +		drm_dp_dpcd_read_link_status(&it6505->aux, link_status);
> +
> +		if (!drm_dp_clock_recovery_ok(link_status, it6505->lane_count))
> +			goto eq_train_fail;
> +
> +		if (drm_dp_channel_eq_ok(link_status, it6505->lane_count)) {
> +			it6505_dpcd_write(it6505, DP_TRAINING_PATTERN_SET,
> +					  DP_TRAINING_PATTERN_DISABLE);
> +			it6505_set_bits(it6505, REG_TRAIN_CTRL0, FORCE_EQ_DONE,
> +					FORCE_EQ_DONE);
> +			return true;
> +		}
> +		DRM_DEV_DEBUG_DRIVER(&it6505->client->dev, "eq not done");
> +
> +		for (i = 0; i < it6505->lane_count; i++) {
> +			lane_voltage_pre_emphasis->voltage_swing[i] =
> +				drm_dp_get_adjust_request_voltage(link_status,
> +								  i) >>
> +				DP_TRAIN_VOLTAGE_SWING_SHIFT;
> +			lane_voltage_pre_emphasis->pre_emphasis[i] =
> +				drm_dp_get_adjust_request_pre_emphasis(
> +					link_status, i) >>
> +				DP_TRAIN_PRE_EMPHASIS_SHIFT;
> +
> +			if (lane_voltage_pre_emphasis->voltage_swing[i] +
> +				    lane_voltage_pre_emphasis->pre_emphasis[i] >
> +			    MAX_EQ_LEVEL)
> +				lane_voltage_pre_emphasis->voltage_swing[i] =
> +					0x03 - lane_voltage_pre_emphasis
> +						       ->pre_emphasis[i];
> +		}
> +	}
> +
> +eq_train_fail:
> +	it6505_dpcd_write(it6505, DP_TRAINING_PATTERN_SET,
> +			  DP_TRAINING_PATTERN_DISABLE);
> +	return false;
> +}
> +
> +static bool it6505_link_start_step_train(struct it6505 *it6505)
> +{
> +	int err;
> +	struct it6505_step_train_para lane_voltage_pre_emphasis = {
> +		.voltage_swing = { 0 },
> +		.pre_emphasis = { 0 },
> +	};
> +
> +	DRM_DEV_DEBUG_DRIVER(&it6505->client->dev, "start");
> +	err = it6505_drm_dp_link_configure(it6505);
> +
> +	if (err < 0)
> +		return false;
> +	if (!it6505_step_cr_train(it6505, &lane_voltage_pre_emphasis))
> +		return false;
> +	if (!it6505_step_eq_train(it6505, &lane_voltage_pre_emphasis))
> +		return false;
> +	return true;
> +}
> +


The whole link training is performed in different drivers in similar 
way, maybe some day someone will be able to abstract out common parts 
and create nice helpers for it.


> +static bool it6505_get_video_status(struct it6505 *it6505)
> +{
> +	int reg_0d;
> +
> +	reg_0d = it6505_read(it6505, REG_SYSTEM_STS);
> +
> +	if (reg_0d < 0)
> +		return false;
> +
> +	return !!(reg_0d & VIDEO_STB);


Again !!


> +}
> +
> +static void it6505_reset_hdcp(struct it6505 *it6505)
> +{
> +	it6505->hdcp_status = HDCP_AUTH_IDLE;
> +	/* Disable CP_Desired */
> +	it6505_set_bits(it6505, REG_HDCP_CTRL1, HDCP_CP_ENABLE, 0x00);
> +	it6505_set_bits(it6505, REG_RESET_CTRL, HDCP_RESET, HDCP_RESET);
> +}
> +
> +static void it6505_start_hdcp(struct it6505 *it6505)
> +{
> +	struct device *dev = &it6505->client->dev;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "start");
> +	it6505_reset_hdcp(it6505);
> +	queue_delayed_work(system_wq, &it6505->hdcp_work,
> +			   msecs_to_jiffies(2400));
> +}
> +
> +static void it6505_stop_hdcp(struct it6505 *it6505)
> +{
> +	it6505_reset_hdcp(it6505);
> +	cancel_delayed_work(&it6505->hdcp_work);
> +}
> +
> +static bool it6505_hdcp_is_ksv_valid(u8 *ksv)
> +{
> +	int i, ones = 0;
> +
> +	/* KSV has 20 1's and 20 0's */
> +	for (i = 0; i < DRM_HDCP_KSV_LEN; i++)
> +		ones += hweight8(ksv[i]);
> +	if (ones != 20)
> +		return false;
> +	return true;
> +}
> +
> +static void it6505_hdcp_part1_auth(struct it6505 *it6505)
> +{
> +	struct device *dev = &it6505->client->dev;
> +	u8 hdcp_bcaps;
> +
> +	it6505_set_bits(it6505, REG_RESET_CTRL, HDCP_RESET, 0x00);
> +	/* Disable CP_Desired */
> +	it6505_set_bits(it6505, REG_HDCP_CTRL1, HDCP_CP_ENABLE, 0x00);
> +
> +	usleep_range(1000, 1500);
> +	hdcp_bcaps = it6505_dpcd_read(it6505, DP_AUX_HDCP_BCAPS);
> +	DRM_DEV_DEBUG_DRIVER(dev, "DPCD[0x68028]: 0x%02x",
> +			     hdcp_bcaps);
> +
> +	if (!hdcp_bcaps)
> +		return;
> +
> +	/* clear the repeater List Chk Done and fail bit */
> +	it6505_set_bits(it6505, REG_HDCP_TRIGGER,
> +			HDCP_TRIGGER_KSV_DONE | HDCP_TRIGGER_KSV_FAIL,
> +			0x00);
> +
> +	/* Enable An Generator */
> +	it6505_set_bits(it6505, REG_HDCP_CTRL2, HDCP_AN_GEN, HDCP_AN_GEN);
> +	/* delay1ms(10);*/
drop the comment - it does not add valuable info
> +	usleep_range(10000, 15000);
> +	/* Stop An Generator */
> +	it6505_set_bits(it6505, REG_HDCP_CTRL2, HDCP_AN_GEN, 0x00);
> +
> +	it6505_set_bits(it6505, REG_HDCP_CTRL1, HDCP_CP_ENABLE, HDCP_CP_ENABLE);
> +
> +	it6505_set_bits(it6505, REG_HDCP_TRIGGER, HDCP_TRIGGER_START,
> +			HDCP_TRIGGER_START);
> +
> +	it6505->hdcp_status = HDCP_AUTH_GOING;
> +}
> +
> +static int it6505_sha1_digest(struct it6505 *it6505, u8 *sha1_input,
> +			      unsigned int size, u8 *output_av)
> +{
> +	struct shash_desc *desc;
> +	struct crypto_shash *tfm;
> +	int err;
> +	struct device *dev = &it6505->client->dev;
> +
> +	tfm = crypto_alloc_shash("sha1", 0, 0);
> +	if (IS_ERR(tfm)) {
> +		DRM_DEV_ERROR(dev, "crypto_alloc_shash sha1 failed");
> +		return PTR_ERR(tfm);
> +	}
> +	desc = kzalloc(sizeof(*desc) + crypto_shash_descsize(tfm), GFP_KERNEL);
> +	if (!desc) {
> +		crypto_free_shash(tfm);
> +		return -ENOMEM;
> +	}
> +
> +	desc->tfm = tfm;
> +	err = crypto_shash_digest(desc, sha1_input, size, output_av);
> +	if (err)
> +		DRM_DEV_ERROR(dev, "crypto_shash_digest sha1 failed");
> +
> +	crypto_free_shash(tfm);
> +	kfree(desc);
> +	return err;
> +}
> +
> +static int it6505_setup_sha1_input(struct it6505 *it6505, u8 *sha1_input)
> +{
> +	struct device *dev = &it6505->client->dev;
> +	u8 binfo[2];
> +	int down_stream_count, i, err, msg_count = 0;
> +
> +	err = it6505_get_dpcd(it6505, DP_AUX_HDCP_BINFO, binfo,
> +			      ARRAY_SIZE(binfo));
> +
> +	if (err < 0) {
> +		DRM_DEV_ERROR(dev, "Read binfo value Fail");
> +		return err;
> +	}
> +
> +	down_stream_count = binfo[0] & 0x7F;
> +	DRM_DEV_DEBUG_DRIVER(dev, "binfo:0x%*ph", (int)ARRAY_SIZE(binfo),
> +			     binfo);
> +
> +	if ((binfo[0] & BIT(7)) || (binfo[1] & BIT(3))) {
> +		DRM_DEV_ERROR(dev, "HDCP max cascade device exceed");
> +		return 0;
> +	}
> +
> +	if (!down_stream_count ||
> +	    (down_stream_count > MAX_HDCP_DOWN_STREAM_COUNT)) {
> +		DRM_DEV_ERROR(dev, "HDCP down stream count Error %d",
> +			      down_stream_count);
> +		return 0;
> +	}
> +
> +	for (i = 0; i < down_stream_count; i++) {
> +		err = it6505_get_dpcd(it6505, DP_AUX_HDCP_KSV_FIFO +
> +				      (i % 3) * DRM_HDCP_KSV_LEN,
> +				      sha1_input + msg_count,
> +				      DRM_HDCP_KSV_LEN);
> +
> +		if (err < 0)
> +			return err;
> +
> +		msg_count += 5;
> +	}
> +
> +	it6505->hdcp_down_stream_count = down_stream_count;
> +	sha1_input[msg_count++] = binfo[0];
> +	sha1_input[msg_count++] = binfo[1];
> +
> +	it6505_set_bits(it6505, REG_HDCP_CTRL2, HDCP_EN_M0_READ,
> +			HDCP_EN_M0_READ);
> +
> +	err = regmap_bulk_read(it6505->regmap, REG_M0_0_7,
> +			       sha1_input + msg_count, 8);
> +
> +	it6505_set_bits(it6505, REG_HDCP_CTRL2, HDCP_EN_M0_READ, 0x00);
> +
> +	if (err < 0) {
> +		DRM_DEV_ERROR(dev, " Warning, Read M value Fail");
> +		return err;
> +	}
> +
> +	msg_count += 8;
> +
> +	return msg_count;
> +}
> +
> +static bool it6505_hdcp_part2_ksvlist_check(struct it6505 *it6505)
> +{
> +	struct device *dev = &it6505->client->dev;
> +	u8 av[5][4], bv[5][4];
> +	int i, err;
> +
> +	i = it6505_setup_sha1_input(it6505, it6505->sha1_input);
> +	if (i <= 0) {
> +		DRM_DEV_ERROR(dev, "SHA-1 Input length error %d", i);
> +		return false;
> +	}
> +
> +	it6505_sha1_digest(it6505, it6505->sha1_input, i, (u8 *)av);
> +
> +	err = it6505_get_dpcd(it6505, DP_AUX_HDCP_V_PRIME(0), (u8 *)bv,
> +			      sizeof(bv));
> +
> +	if (err < 0) {
> +		DRM_DEV_ERROR(dev, "Read V' value Fail");
> +		return false;
> +	}
> +
> +	for (i = 0; i < 5; i++)
> +		if ((bv[i][3] != av[i][0]) || (bv[i][2] != av[i][1]) ||
> +		    (bv[i][1] != av[i][2]) || (bv[i][0] != av[i][3]))
> +			return false;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "V' all match!!");
> +	return true;
> +}
> +
> +static void it6505_hdcp_wait_ksv_list(struct work_struct *work)
> +{
> +	struct it6505 *it6505 = container_of(work, struct it6505,
> +					     hdcp_wait_ksv_list);
> +	struct device *dev = &it6505->client->dev;
> +	unsigned int timeout = 5000;
> +	u8 bstatus = 0;
> +	bool ksv_list_check;
> +
> +	timeout /= 20;
> +	while (timeout > 0) {
> +		if (!it6505_get_sink_hpd_status(it6505))
> +			return;
> +
> +		bstatus = it6505_dpcd_read(it6505, DP_AUX_HDCP_BSTATUS);
> +
> +		if (bstatus & DP_BSTATUS_READY)
> +			break;
> +
> +		msleep(20);
> +		timeout--;
> +	}
> +
> +	if (timeout == 0) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "timeout and ksv list wait failed");
> +		goto timeout;
> +	}
> +
> +	ksv_list_check = it6505_hdcp_part2_ksvlist_check(it6505);
> +	DRM_DEV_DEBUG_DRIVER(dev, "ksv list ready, ksv list check %s",
> +			     ksv_list_check ? "pass" : "fail");
> +	if (ksv_list_check) {
> +		it6505_set_bits(it6505, REG_HDCP_TRIGGER,
> +				HDCP_TRIGGER_KSV_DONE, HDCP_TRIGGER_KSV_DONE);
> +		return;
> +	}
> +timeout:
> +	it6505_set_bits(it6505, REG_HDCP_TRIGGER,
> +			HDCP_TRIGGER_KSV_DONE | HDCP_TRIGGER_KSV_FAIL,
> +			HDCP_TRIGGER_KSV_DONE | HDCP_TRIGGER_KSV_FAIL);
> +}
> +
> +static void it6505_hdcp_work(struct work_struct *work)
> +{
> +	struct it6505 *it6505 = container_of(work, struct it6505,
> +					     hdcp_work.work);
> +	struct device *dev = &it6505->client->dev;
> +	int ret;
> +	u8 link_status[DP_LINK_STATUS_SIZE] = { 0 };
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "start");
> +
> +	if (!it6505_get_sink_hpd_status(it6505))
> +		return;
> +
> +	ret = drm_dp_dpcd_read_link_status(&it6505->aux, link_status);
> +	DRM_DEV_DEBUG_DRIVER(dev, "ret: %d link_status: %*ph", ret,
> +			     (int)sizeof(link_status), link_status);
> +
> +	if ((ret < 0) || !drm_dp_channel_eq_ok(link_status, it6505->lane_count)
> +	    || !it6505_get_video_status(it6505)) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "link train not done or no video");
> +		return;
> +	}
> +
> +	ret = it6505_get_dpcd(it6505, DP_AUX_HDCP_BKSV, it6505->bksvs,
> +			      ARRAY_SIZE(it6505->bksvs));
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "fail to get bksv  ret: %d", ret);
> +		it6505_set_bits(it6505, REG_HDCP_TRIGGER,
> +				HDCP_TRIGGER_KSV_FAIL, HDCP_TRIGGER_KSV_FAIL);
> +	}
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "bksv = 0x%*ph",
> +			     (int)ARRAY_SIZE(it6505->bksvs), it6505->bksvs);
> +
> +	if (!it6505_hdcp_is_ksv_valid(it6505->bksvs)) {
> +		DRM_DEV_ERROR(dev, "Display Port bksv not valid");
> +		it6505_set_bits(it6505, REG_HDCP_TRIGGER,
> +				HDCP_TRIGGER_KSV_FAIL, HDCP_TRIGGER_KSV_FAIL);
> +	}
> +
> +	it6505_hdcp_part1_auth(it6505);
> +}
> +
> +static void it6505_show_hdcp_info(struct it6505 *it6505)
> +{
> +	struct device *dev = &it6505->client->dev;
> +	int i;
> +	u8 *sha1 = it6505->sha1_input;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "hdcp_status: %d is_repeater: %d",
> +			     it6505->hdcp_status, it6505->is_repeater);
> +	DRM_DEV_DEBUG_DRIVER(dev, "bksv = 0x%*ph",
> +			     (int)ARRAY_SIZE(it6505->bksvs), it6505->bksvs);
> +
> +	if (it6505->is_repeater) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "hdcp_down_stream_count: %d",
> +				     it6505->hdcp_down_stream_count);
> +		DRM_DEV_DEBUG_DRIVER(dev, "sha1_input: 0x%*ph",
> +				     (int)ARRAY_SIZE(it6505->sha1_input),
> +				     it6505->sha1_input);
> +		for (i = 0; i < it6505->hdcp_down_stream_count; i++) {
> +			DRM_DEV_DEBUG_DRIVER(dev, "KSV_%d = 0x%*ph", i,
> +					     DRM_HDCP_KSV_LEN, sha1);
> +			sha1 += DRM_HDCP_KSV_LEN;
> +		}
> +		DRM_DEV_DEBUG_DRIVER(dev, "binfo: 0x%2ph M0: 0x%8ph",
> +				     sha1, sha1 + 2);
> +	}
> +}
> +
> +static void it6505_stop_link_train(struct it6505 *it6505)
> +{
> +	it6505->link_state = LINK_IDLE;
> +	cancel_work_sync(&it6505->link_works);
> +	it6505_write(it6505, REG_TRAIN_CTRL1, FORCE_RETRAIN);
> +}
> +
> +static void it6505_link_train_ok(struct it6505 *it6505)
> +{
> +	struct device *dev = &it6505->client->dev;
> +
> +	it6505->link_state = LINK_OK;
> +	/* disalbe mute enable avi info frame */
> +	it6505_set_bits(it6505, REG_DATA_MUTE_CTRL, EN_VID_MUTE, 0x00);
> +	it6505_set_bits(it6505, REG_INFOFRAME_CTRL,
> +			EN_VID_CTRL_PKT, EN_VID_CTRL_PKT);
> +
> +	if (it6505_audio_input(it6505)) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "Enable audio!");
> +		it6505_enable_audio(it6505);
> +	}
> +
> +	if (it6505->hdcp_desired)
> +		it6505_start_hdcp(it6505);
> +}
> +
> +static void it6505_link_step_train_process(struct it6505 *it6505)
> +{
> +	struct device *dev = &it6505->client->dev;
> +	int ret, i, step_retry = 3;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "Start step train");
> +
> +	if (it6505->sink_count == 0) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "it6505->sink_count:%d, force eq",
> +				     it6505->sink_count);
> +		it6505_set_bits(it6505,	REG_TRAIN_CTRL0, FORCE_EQ_DONE,
> +				FORCE_EQ_DONE);
> +		return;
> +	}
> +
> +	if (!it6505->step_train) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "not support step train");
> +		return;
> +	}
> +
> +	/* setp training start here */
> +	for (i = 0; i < step_retry; i++) {
> +		it6505_set_bits(it6505, REG_TRAIN_CTRL0,
> +				FORCE_CR_DONE | FORCE_EQ_DONE, 0x00);
> +		it6505_dpcd_write(it6505, DP_TRAINING_PATTERN_SET,
> +				  DP_TRAINING_PATTERN_DISABLE);
> +		ret = it6505_link_start_step_train(it6505);
> +		DRM_DEV_DEBUG_DRIVER(dev, "step train %s, retry:%d times",
> +				     ret ? "pass" : "failed", i + 1);
> +		if (ret) {
> +			it6505_link_train_ok(it6505);
> +			return;
> +		}
> +	}
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "training fail");
> +	it6505->link_state = LINK_IDLE;
> +	it6505_video_reset(it6505);
> +}
> +
> +static void it6505_link_training_work(struct work_struct *work)
> +{
> +	struct it6505 *it6505 = container_of(work, struct it6505, link_works);
> +	struct device *dev = &it6505->client->dev;
> +	int ret;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "it6505->sink_count: %d",
> +			     it6505->sink_count);
> +
> +	if (!it6505_get_sink_hpd_status(it6505))
> +		return;
> +
> +	it6505_link_training_setup(it6505);
> +	it6505_reset_hdcp(it6505);
> +	it6505_aux_reset(it6505);
> +
> +	if (it6505->auto_train_retry < 1) {
> +		it6505_link_step_train_process(it6505);
> +		return;
> +	}
> +
> +	ret = it6505_link_start_auto_train(it6505);
> +	DRM_DEV_DEBUG_DRIVER(dev, "auto train %s, auto_train_retry: %d",
> +			     ret ? "pass" : "failed", it6505->auto_train_retry);
> +	it6505->auto_train_retry--;
> +
> +	if (ret) {
> +		it6505_link_train_ok(it6505);
> +		return;
> +	}
> +
> +	it6505_dump(it6505);
> +}
> +
> +static void it6505_plugged_status_to_codec(struct it6505 *it6505)
> +{
> +	enum drm_connector_status status = it6505->connector_status;
> +
> +	if (it6505->plugged_cb && it6505->codec_dev)
> +		it6505->plugged_cb(it6505->codec_dev,
> +				   status == connector_status_connected);
> +}
> +
> +static int it6505_process_hpd_irq(struct it6505 *it6505)
> +{
> +	struct device *dev = &it6505->client->dev;
> +	int ret, dpcd_sink_count, dp_irq_vector, bstatus;
> +	u8 link_status[DP_LINK_STATUS_SIZE];
> +
> +	if (!it6505_get_sink_hpd_status(it6505)) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "HPD_IRQ HPD low");
> +		it6505->sink_count = 0;
> +		return 0;
> +	}
> +
> +	ret = it6505_dpcd_read(it6505, DP_SINK_COUNT);
> +	if (ret < 0)
> +		return ret;
> +
> +	dpcd_sink_count = DP_GET_SINK_COUNT(ret);
> +	DRM_DEV_DEBUG_DRIVER(dev, "dpcd_sink_count: %d it6505->sink_count:%d",
> +			     dpcd_sink_count, it6505->sink_count);
> +
> +	if (it6505->branch_device && dpcd_sink_count != it6505->sink_count) {
> +		memset(it6505->dpcd, 0, sizeof(it6505->dpcd));
> +		it6505->sink_count = dpcd_sink_count;
> +		kfree(it6505->edid);
> +		it6505->edid = NULL;
> +		it6505_reset_logic(it6505);
> +		it6505_int_mask_enable(it6505);
> +		it6505_init(it6505);
> +		return 0;
> +	}
> +
> +	dp_irq_vector = it6505_dpcd_read(it6505, DP_DEVICE_SERVICE_IRQ_VECTOR);
> +	if (dp_irq_vector < 0)
> +		return dp_irq_vector;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "dp_irq_vector = 0x%02x", dp_irq_vector);
> +
> +	if (dp_irq_vector & DP_CP_IRQ) {
> +		it6505_set_bits(it6505, REG_HDCP_TRIGGER, HDCP_TRIGGER_CPIRQ,
> +				HDCP_TRIGGER_CPIRQ);
> +
> +		bstatus = it6505_dpcd_read(it6505, DP_AUX_HDCP_BSTATUS);
> +		if (bstatus < 0)
> +			return bstatus;
> +
> +		DRM_DEV_DEBUG_DRIVER(dev, "Bstatus = 0x%02x", bstatus);
> +	}
> +
> +	ret = drm_dp_dpcd_read_link_status(&it6505->aux, link_status);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "Fail to read link status ret: %d",
> +			      ret);
> +		return ret;
> +	}
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "link status = 0x%*ph",
> +			     (int)ARRAY_SIZE(link_status), link_status);
> +
> +	if (!drm_dp_channel_eq_ok(link_status, it6505->lane_count)) {
> +		it6505->auto_train_retry = AUTO_TRAIN_RETRY;
> +		it6505_video_reset(it6505);
> +	}
> +
> +	return 0;
> +}
> +
> +static void it6505_check_reg06(struct it6505 *it6505, unsigned int reg06)
> +{
> +	struct device *dev = &it6505->client->dev;
> +	bool data;
> +
> +	if (reg06 & INT_HPD_CHANGE) {
> +		data = it6505_get_sink_hpd_status(it6505);
> +		DRM_DEV_DEBUG_DRIVER(dev, "hpd change interrupt, change to %s",
> +				     data ? "high" : "low");
> +		if (it6505->connector.dev)
> +			drm_helper_hpd_irq_event(it6505->connector.dev);
> +		DRM_DEV_DEBUG_DRIVER(dev, "it6505->sink_count: %d",
> +				     it6505->sink_count);
> +
> +		if (data) {
> +			wait_for_completion_timeout(&it6505->wait_edid_complete,
> +						    msecs_to_jiffies(6000));
> +			it6505_lane_termination_on(it6505);
> +			it6505_lane_power_on(it6505);
> +
> +			/*
> +			 * for some dongle which issue HPD_irq
> +			 * when sink count change from  0->1
> +			 * it6505 not able to receive HPD_IRQ
> +			 * if HW never go into trainig done
> +			 */
> +
> +			if (it6505->branch_device && it6505->sink_count == 0)
> +				schedule_work(&it6505->link_works);
> +
> +			if (!it6505_get_video_status(it6505))
> +				it6505_video_reset(it6505);
> +
> +			it6505_calc_video_info(it6505);
> +		} else {
> +			kfree(it6505->edid);
> +			it6505->edid = NULL;
> +			memset(it6505->dpcd, 0, sizeof(it6505->dpcd));
> +
> +			if (it6505->hdcp_desired)
> +				it6505_stop_hdcp(it6505);
> +
> +			it6505_video_disable(it6505);
> +			it6505_disable_audio(it6505);
> +			it6505_stop_link_train(it6505);
> +			it6505_lane_off(it6505);
> +			return;
> +		}
> +	}
> +
> +	if (reg06 & INT_RECEIVE_HPD_IRQ) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "hpd_irq interrupt");
> +
> +		if (it6505_process_hpd_irq(it6505) < 0)
> +			DRM_DEV_DEBUG_DRIVER(dev, "process hpd_irq fail!");
> +	}
> +
> +	if (reg06 & INT_SCDT_CHANGE) {
> +		data = it6505_get_video_status(it6505);
> +		DRM_DEV_DEBUG_DRIVER(dev, "video stable change interrupt, %s",
> +				     data ? "stable" : "unstable");
> +		it6505_calc_video_info(it6505);
> +
> +		if (data)
> +			schedule_work(&it6505->link_works);
> +	}
> +
> +	if (reg06 & INT_HDCP_DONE) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "hdcp done interrupt");
> +		it6505->hdcp_status = HDCP_AUTH_DONE;
> +		it6505_show_hdcp_info(it6505);
> +	}
> +
> +	if (reg06 & INT_HDCP_FAIL) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "hdcp fail interrupt");
> +		it6505->hdcp_status = HDCP_AUTH_IDLE;
> +		it6505_show_hdcp_info(it6505);
> +		it6505_start_hdcp(it6505);
> +	}
> +}
> +
> +static void it6505_check_reg07(struct it6505 *it6505, unsigned int reg07)
> +{
> +	struct device *dev = &it6505->client->dev;
> +
> +	if (reg07 & INT_AUX_CMD_FAIL)
> +		DRM_DEV_DEBUG_DRIVER(dev, "AUX PC Request Fail Interrupt");
> +
> +	if (reg07 & INT_HDCP_KSV_CHECK) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "HDCP event Interrupt");
> +		schedule_work(&it6505->hdcp_wait_ksv_list);
> +	}
> +
> +	if (reg07 & INT_AUDIO_FIFO_ERROR) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "audio fifo error Interrupt");
> +
> +		if (it6505_audio_input(it6505))
> +			it6505_enable_audio(it6505);
> +	}
> +
> +}
> +
> +static void it6505_check_reg08(struct it6505 *it6505, unsigned int reg08)
> +{
> +	struct device *dev = &it6505->client->dev;
> +
> +	if (reg08 & INT_LINK_TRAIN_FAIL) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "link training fail interrupt");
> +		schedule_work(&it6505->link_works);
> +	}
> +
> +	if (reg08 & INT_VID_FIFO_ERROR) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "video fifo overflow interrupt");
> +		it6505->auto_train_retry = AUTO_TRAIN_RETRY;
> +		flush_work(&it6505->link_works);
> +		it6505_stop_hdcp(it6505);
> +		it6505_video_reset(it6505);
> +	}
> +
> +	if (reg08 & INT_IO_LATCH_FIFO_OVERFLOW) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "IO latch fifo overflow interrupt");
> +		it6505->auto_train_retry = AUTO_TRAIN_RETRY;
> +		flush_work(&it6505->link_works);
> +		it6505_stop_hdcp(it6505);
> +		it6505_video_reset(it6505);
> +	}
> +}
> +
> +static irqreturn_t it6505_int_threaded_handler(int unused, void *data)
> +{
> +	struct it6505 *it6505 = data;
> +	struct device *dev = &it6505->client->dev;
> +	int reg06, reg07, reg08;
> +
> +	msleep(100);
> +	mutex_lock(&it6505->extcon_lock);
> +
> +	if (it6505->enable_drv_hold || !it6505->powered)
> +		goto unlock;
> +
> +	reg06 = it6505_read(it6505, INT_STATUS_01);
> +	reg07 = it6505_read(it6505, INT_STATUS_02);
> +	reg08 = it6505_read(it6505, INT_STATUS_03);
> +
> +	it6505_write(it6505, INT_STATUS_01, reg06);
> +	it6505_write(it6505, INT_STATUS_02, reg07);
> +	it6505_write(it6505, INT_STATUS_03, reg08);
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "reg06 = 0x%02x", reg06);
> +	DRM_DEV_DEBUG_DRIVER(dev, "reg07 = 0x%02x", reg07);
> +	DRM_DEV_DEBUG_DRIVER(dev, "reg08 = 0x%02x", reg08);
> +	it6505_debug_print(it6505, REG_SYSTEM_STS, "");
> +
> +	if (reg06 != 0)
> +		it6505_check_reg06(it6505, reg06);
> +
> +	if (reg07 != 0)
> +		it6505_check_reg07(it6505, reg07);
> +
> +	if (reg08 != 0)
> +		it6505_check_reg08(it6505, reg08);


The whole irq handler looks ugly, you can collate all three INT_STATUS_* 
regs into one value and then check which bits are on and then call 
apropriate irq handler.

See [1] for example.

[1]: 
https://elixir.bootlin.com/linux/v4.15/source/drivers/gpu/drm/bridge/sil-sii8620.c#L2055



> +
> +unlock:
> +	mutex_unlock(&it6505->extcon_lock);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int it6505_poweron(struct it6505 *it6505)
> +{
> +	struct device *dev = &it6505->client->dev;
> +	struct it6505_platform_data *pdata = &it6505->pdata;
> +	int err;
> +
> +	if (it6505->powered) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "it6505 already powered on");
> +		return 0;
> +	}
> +
> +	if (pdata->pwr18) {
> +		err = regulator_enable(pdata->pwr18);
> +		if (err) {
> +			DRM_DEV_DEBUG_DRIVER(dev, "Failed to enable VDD18: %d",
> +					     err);
> +			return err;
> +		}
> +	}
> +
> +	if (pdata->ovdd) {
> +		/* time interval between IVDD and OVDD at least be 1ms */
> +		usleep_range(1000, 2000);
> +		err = regulator_enable(pdata->ovdd);
> +		if (err) {
> +			regulator_disable(pdata->pwr18);
> +			return err;
> +		}
> +	}
> +	/* time interval between OVDD and SYSRSTN at least be 10ms */
> +	if (pdata->gpiod_reset) {
> +		usleep_range(10000, 20000);
> +		gpiod_set_value_cansleep(pdata->gpiod_reset, 0);
> +		usleep_range(1000, 2000);
> +		gpiod_set_value_cansleep(pdata->gpiod_reset, 1);
> +		usleep_range(10000, 20000);
> +	}
> +
> +	it6505_reset_logic(it6505);
> +	it6505_int_mask_enable(it6505);
> +	it6505_init(it6505);
> +	it6505_lane_off(it6505);
> +
> +	it6505->powered = true;
> +
> +	return 0;
> +}
> +
> +static int it6505_poweroff(struct it6505 *it6505)
> +{
> +	struct device *dev = &it6505->client->dev;
> +	struct it6505_platform_data *pdata = &it6505->pdata;
> +	int err;
> +
> +	if (!it6505->powered) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "power had been already off");
> +		return 0;
> +	}
> +
> +	if (pdata->gpiod_reset)
> +		gpiod_set_value_cansleep(pdata->gpiod_reset, 0);
> +
> +	if (pdata->pwr18) {
> +		err = regulator_disable(pdata->pwr18);
> +		if (err)
> +			return err;
> +	}
> +
> +	if (pdata->ovdd) {
> +		err = regulator_disable(pdata->ovdd);
> +		if (err)
> +			return err;
> +	}
> +
> +	it6505->powered = false;
> +	kfree(it6505->edid);
> +	it6505->edid = NULL;
> +	it6505->sink_count = 0;
> +
> +	return 0;
> +}
> +
> +static inline struct it6505 *connector_to_it6505(struct drm_connector *c)
> +{
> +	return container_of(c, struct it6505, connector);
> +}
> +
> +static int it6505_get_modes(struct drm_connector *connector)
> +{
> +	struct it6505 *it6505 = connector_to_it6505(connector);
> +	int err, num_modes = 0, i;
> +	struct device *dev = &it6505->client->dev;
> +
> +	if (it6505->edid)
> +		return drm_add_edid_modes(connector, it6505->edid);
> +
> +	mutex_lock(&it6505->mode_lock);
> +	reinit_completion(&it6505->wait_edid_complete);
> +
> +	for (i = 0; i < 3; i++) {
> +		if (!it6505_get_sink_hpd_status(it6505))
> +			goto unlock;
> +
> +		it6505->edid = drm_do_get_edid(&it6505->connector,
> +					       it6505_get_edid_block, it6505);
> +
> +		if (it6505->edid)
> +			break;
> +	}
> +	if (!it6505->edid) {
> +		DRM_DEV_ERROR(dev, "Failed to read EDID");
> +		num_modes = -EIO;
> +		goto unlock;
> +	}
> +
> +	err = drm_connector_update_edid_property(connector, it6505->edid);
> +	if (err) {
> +		DRM_DEV_ERROR(dev, "Failed to update EDID property: %d", err);
> +		num_modes = err;
> +		goto unlock;
> +	}
> +
> +	num_modes = drm_add_edid_modes(connector, it6505->edid);
> +
> +unlock:
> +	complete(&it6505->wait_edid_complete);
> +	mutex_unlock(&it6505->mode_lock);
> +
> +	return num_modes;
> +}
> +
> +static const struct drm_connector_helper_funcs it6505_connector_helper_funcs = {
> +	.get_modes = it6505_get_modes,
> +};
> +
> +static enum drm_connector_status it6505_detect(struct drm_connector *connector,
> +					       bool force)
> +{
> +	struct it6505 *it6505 = connector_to_it6505(connector);
> +	struct device *dev = &it6505->client->dev;
> +	enum drm_connector_status status = connector_status_disconnected;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "it6505->sink_count:%d powered:%d",
> +			     it6505->sink_count, it6505->powered);
> +
> +	mutex_lock(&it6505->mode_lock);
> +
> +	if (!it6505->powered)
> +		goto unlock;
> +
> +	if (it6505->enable_drv_hold) {
> +		status = it6505_get_sink_hpd_status(it6505) ?
> +					connector_status_connected :
> +					connector_status_disconnected;
> +		goto unlock;
> +	}
> +
> +	if (it6505_get_sink_hpd_status(it6505)) {
> +		it6505_aux_on(it6505);
> +		it6505_drm_dp_link_probe(&it6505->aux, &it6505->link);
> +		it6505_drm_dp_link_power_up(&it6505->aux, &it6505->link);
> +		it6505->auto_train_retry = AUTO_TRAIN_RETRY;
> +
> +		if (it6505->dpcd[0] == 0) {
> +			it6505_get_dpcd(it6505, DP_DPCD_REV, it6505->dpcd,
> +					ARRAY_SIZE(it6505->dpcd));
> +			it6505_variable_config(it6505);
> +			it6505_parse_link_capabilities(it6505);
> +		}
> +
> +		it6505->sink_count = DP_GET_SINK_COUNT(it6505_dpcd_read(it6505,
> +						       DP_SINK_COUNT));
> +		DRM_DEV_DEBUG_DRIVER(dev, "it6505->sink_count:%d branch:%d",
> +				     it6505->sink_count, it6505->branch_device);
> +
> +		if (it6505->branch_device) {
> +			status = (it6505->sink_count != 0) ?
> +				 connector_status_connected :
> +				 connector_status_disconnected;
> +		} else {
> +			status = connector_status_connected;
> +		}
> +	} else {
> +		it6505->sink_count = 0;
> +		memset(it6505->dpcd, 0, sizeof(it6505->dpcd));
> +	}
> +
> +unlock:
> +	if (it6505->connector_status != status) {
> +		it6505->connector_status = status;
> +		it6505_plugged_status_to_codec(it6505);
> +	}
> +
> +	mutex_unlock(&it6505->mode_lock);
> +
> +	return status;
> +}
> +
> +static const struct drm_connector_funcs it6505_connector_funcs = {
> +	.fill_modes = drm_helper_probe_single_connector_modes,
> +	.detect = it6505_detect,
> +	.destroy = drm_connector_cleanup,
> +	.reset = drm_atomic_helper_connector_reset,
> +	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
> +	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> +};
> +
> +static int it6505_extcon_notifier(struct notifier_block *self,
> +				  unsigned long event, void *ptr)
> +{
> +	struct it6505 *it6505 = container_of(self, struct it6505, event_nb);
> +
> +	schedule_work(&it6505->extcon_wq);
> +	return NOTIFY_DONE;
> +}
> +
> +static void it6505_extcon_work(struct work_struct *work)
> +{
> +	struct it6505 *it6505 = container_of(work, struct it6505, extcon_wq);
> +	struct device *dev = &it6505->client->dev;
> +	int state = extcon_get_state(it6505->extcon, EXTCON_DISP_DP);
> +	unsigned int pwroffretry = 0;
> +
> +	if (it6505->enable_drv_hold)
> +		return;
> +
> +	mutex_lock(&it6505->extcon_lock);
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "EXTCON_DISP_DP = 0x%02x", state);
> +	if (state > 0) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "start to power on");
> +		msleep(100);
> +		it6505_poweron(it6505);
> +	} else {
> +		DRM_DEV_DEBUG_DRIVER(dev, "start to power off");
> +		while (it6505_poweroff(it6505) && pwroffretry++ < 5) {
> +			DRM_DEV_DEBUG_DRIVER(dev, "power off fail %d times",
> +					     pwroffretry);
> +		}
> +
> +		drm_helper_hpd_irq_event(it6505->connector.dev);
> +		memset(it6505->dpcd, 0, sizeof(it6505->dpcd));
> +		DRM_DEV_DEBUG_DRIVER(dev, "power off it6505 success!");
> +	}
> +
> +	mutex_unlock(&it6505->extcon_lock);
> +}
> +
> +static int it6505_use_notifier_module(struct it6505 *it6505)
> +{
> +	int ret;
> +	struct device *dev = &it6505->client->dev;
> +
> +	it6505->event_nb.notifier_call = it6505_extcon_notifier;
> +	INIT_WORK(&it6505->extcon_wq, it6505_extcon_work);
> +	ret = devm_extcon_register_notifier(&it6505->client->dev,
> +					    it6505->extcon, EXTCON_DISP_DP,
> +					    &it6505->event_nb);
> +	if (ret) {
> +		DRM_DEV_ERROR(dev, "failed to register notifier for DP");
> +		return ret;
> +	}
> +
> +	schedule_work(&it6505->extcon_wq);
> +
> +	return 0;
> +}
> +
> +static void it6505_remove_notifier_module(struct it6505 *it6505)
> +{
> +	if (it6505->extcon) {
> +		devm_extcon_unregister_notifier(&it6505->client->dev,
> +						it6505->extcon,	EXTCON_DISP_DP,
> +						&it6505->event_nb);
> +
> +		flush_work(&it6505->extcon_wq);
> +	}
> +}
> +
> +static void __maybe_unused it6505_delayed_audio(struct work_struct *work)
> +{
> +	struct it6505 *it6505 = container_of(work, struct it6505,
> +					     delayed_audio.work);
> +
> +	DRM_DEV_DEBUG_DRIVER(&it6505->client->dev, "start");
> +
> +	if (!it6505->powered)
> +		return;
> +
> +	if (!it6505->enable_drv_hold)
> +		it6505_enable_audio(it6505);
> +}
> +
> +static int __maybe_unused it6505_audio_setup_hw_params(struct it6505 *it6505,
> +					struct hdmi_codec_params *params)
> +{
> +	struct device *dev = &it6505->client->dev;
> +	int i = 0;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "%s %d Hz, %d bit, %d channels\n", __func__,
> +			     params->sample_rate, params->sample_width,
> +			     params->cea.channels);
> +
> +	if (!it6505->bridge.encoder)
> +		return -ENODEV;
> +
> +	if (params->cea.channels <= 1 || params->cea.channels > 8) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "channel number: %d not support",
> +				     it6505->audio.channel_count);
> +		return -EINVAL;
> +	}
> +
> +	it6505->audio.channel_count = params->cea.channels;
> +
> +	while (i < ARRAY_SIZE(audio_sample_rate_map) &&
> +	       params->sample_rate !=
> +		       audio_sample_rate_map[i].sample_rate_value) {
> +		i++;
> +	}
> +	if (i == ARRAY_SIZE(audio_sample_rate_map)) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "sample rate: %d Hz not support",
> +				     params->sample_rate);
> +		return -EINVAL;
> +	}
> +	it6505->audio.sample_rate = audio_sample_rate_map[i].rate;
> +
> +	switch (params->sample_width) {
> +	case 16:
> +		it6505->audio.word_length = WORD_LENGTH_16BIT;
> +		break;
> +	case 18:
> +		it6505->audio.word_length = WORD_LENGTH_18BIT;
> +		break;
> +	case 20:
> +		it6505->audio.word_length = WORD_LENGTH_20BIT;
> +		break;
> +	case 24:
> +	case 32:
> +		it6505->audio.word_length = WORD_LENGTH_24BIT;
> +		break;
> +	default:
> +		DRM_DEV_DEBUG_DRIVER(dev, "wordlength: %d bit not support",
> +				     params->sample_width);
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static void __maybe_unused it6505_audio_shutdown(struct device *dev, void *data)
> +{
> +	struct it6505 *it6505 = dev_get_drvdata(dev);
> +
> +	if (it6505->powered)
> +		it6505_disable_audio(it6505);
> +}
> +
> +static int __maybe_unused it6505_audio_hook_plugged_cb(struct device *dev,
> +						       void *data,
> +						       hdmi_codec_plugged_cb fn,
> +						       struct device *codec_dev)
> +{
> +	struct it6505 *it6505 = data;
> +
> +	it6505->plugged_cb = fn;
> +	it6505->codec_dev = codec_dev;
> +	it6505_plugged_status_to_codec(it6505);
> +
> +	return 0;
> +}
> +
> +static inline struct it6505 *bridge_to_it6505(struct drm_bridge *bridge)
> +{
> +	return container_of(bridge, struct it6505, bridge);
> +}
> +
> +static void it6505_bridge_mode_set(struct drm_bridge *bridge,
> +				   const struct drm_display_mode *mode,
> +				   const struct drm_display_mode *adjusted_mode)
> +{
> +	struct it6505 *it6505 = bridge_to_it6505(bridge);
> +	struct hdmi_avi_infoframe frame;
> +	int err;
> +	struct device *dev = &it6505->client->dev;
> +
> +	if (WARN_ON(!it6505->powered))
> +		return;
> +
> +	mutex_lock(&it6505->mode_lock);
> +
> +	err = drm_hdmi_avi_infoframe_from_display_mode(&frame,
> +						       &it6505->connector,
> +						       adjusted_mode);
> +	if (err) {
> +		DRM_DEV_ERROR(dev, "Failed to setup AVI infoframe: %d", err);
> +		goto unlock;
> +	}
> +
> +	it6505_update_video_parameter(it6505, adjusted_mode);
> +
> +	err = it6505_send_video_infoframe(it6505, &frame);
> +	if (err)
> +		DRM_DEV_ERROR(dev, "Failed to send AVI infoframe: %d", err);
> +
> +unlock:
> +	mutex_unlock(&it6505->mode_lock);
> +}
> +
> +static int it6505_bridge_attach(struct drm_bridge *bridge,
> +				enum drm_bridge_attach_flags flags)
> +{
> +	struct it6505 *it6505 = bridge_to_it6505(bridge);
> +	struct device *dev = &it6505->client->dev;
> +	int err;
> +
> +	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
> +		DRM_ERROR("Fix bridge driver to make connector optional!");
> +		return 0;
Error should be returned here
> +	}
> +
> +	if (!bridge->encoder) {
> +		DRM_DEV_ERROR(dev, "Parent encoder object not found");
> +		return -ENODEV;
> +	}
> +
> +	err = drm_connector_init(bridge->dev, &it6505->connector,
> +				 &it6505_connector_funcs,
> +				 DRM_MODE_CONNECTOR_DisplayPort);
> +	if (err < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to initialize connector: %d", err);
> +		return err;
> +	}
> +
> +	drm_connector_helper_add(&it6505->connector,
> +				 &it6505_connector_helper_funcs);
> +
> +	it6505->connector.polled = DRM_CONNECTOR_POLL_HPD;
> +
> +	err = drm_connector_attach_encoder(&it6505->connector, bridge->encoder);
> +	if (err < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to link up connector to encoder: %d",
> +			      err);
> +		goto cleanup_connector;
> +	}
> +
> +	err = drm_connector_register(&it6505->connector);
> +	if (err < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to register connector: %d", err);
> +		goto cleanup_connector;
> +	}
> +
> +	if (it6505->extcon) {
> +		err = it6505_use_notifier_module(it6505);
> +		if (err < 0) {
> +			drm_connector_unregister(&it6505->connector);
> +			goto cleanup_connector;
> +		}
> +	}
> +
> +	return 0;
> +
> +cleanup_connector:
> +	drm_connector_cleanup(&it6505->connector);
> +	return err;
> +}
> +
> +static void it6505_bridge_detach(struct drm_bridge *bridge)
> +{
> +	struct it6505 *it6505 = bridge_to_it6505(bridge);
> +
> +	flush_work(&it6505->link_works);
> +	it6505_remove_notifier_module(it6505);
> +	drm_connector_unregister(&it6505->connector);
> +	drm_connector_cleanup(&it6505->connector);
> +}
> +
> +static enum drm_mode_status
> +it6505_bridge_mode_valid(struct drm_bridge *bridge,
> +			 const struct drm_display_info *info,
> +			 const struct drm_display_mode *mode)
> +{
> +	struct it6505 *it6505 = bridge_to_it6505(bridge);
> +
> +	if (mode->flags & DRM_MODE_FLAG_INTERLACE)
> +		return MODE_NO_INTERLACE;
> +
> +	if (mode->clock > DPI_PIXEL_CLK_MAX)
> +		return MODE_CLOCK_HIGH;
> +
> +	it6505->video_info.clock = mode->clock;
> +
> +	return MODE_OK;
> +}
> +
> +static void it6505_bridge_enable(struct drm_bridge *bridge)
> +{
> +	struct it6505 *it6505 = bridge_to_it6505(bridge);
> +
> +	it6505_int_mask_enable(it6505);
> +	it6505_video_reset(it6505);
> +}
> +
> +static void it6505_bridge_disable(struct drm_bridge *bridge)
> +{
> +	struct it6505 *it6505 = bridge_to_it6505(bridge);
> +
> +	if (it6505->powered)
> +		it6505_video_disable(it6505);
> +}
> +
> +static enum drm_connector_status
> +it6505_bridge_detect(struct drm_bridge *bridge)
> +{
> +	struct it6505 *it6505 = bridge_to_it6505(bridge);
> +
> +	return it6505_detect(&it6505->connector, 0);
> +}
> +
> +static struct edid *it6505_bridge_get_edid(struct drm_bridge *bridge,
> +					   struct drm_connector *connector)
> +{
> +	struct it6505 *it6505 = bridge_to_it6505(bridge);
> +	struct device *dev = &it6505->client->dev;
> +	struct edid *edid;
> +
> +	edid = drm_do_get_edid(&it6505->connector, it6505_get_edid_block,
> +			       it6505);
> +
> +	if (!edid) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "failed to get edid!");
> +		return NULL;
> +	}
> +
> +	return edid;
> +}
> +
> +static const struct drm_bridge_funcs it6505_bridge_funcs = {
> +	.attach = it6505_bridge_attach,
> +	.detach = it6505_bridge_detach,
> +	.mode_valid = it6505_bridge_mode_valid,
> +	.mode_set = it6505_bridge_mode_set,
> +	.enable = it6505_bridge_enable,
> +	.disable = it6505_bridge_disable,
> +	.detect = it6505_bridge_detect,
> +	.get_edid = it6505_bridge_get_edid,
> +};
> +
> +#ifdef CONFIG_PM_SLEEP
> +
> +static int it6505_bridge_resume(struct device *dev)
> +{
> +	struct it6505 *it6505 = dev_get_drvdata(dev);
> +
> +	return it6505_poweron(it6505);
> +}
> +
> +static int it6505_bridge_suspend(struct device *dev)
> +{
> +	struct it6505 *it6505 = dev_get_drvdata(dev);
> +
> +	return it6505_poweroff(it6505);
> +}
> +
> +static SIMPLE_DEV_PM_OPS(it6505_bridge_pm_ops, it6505_bridge_suspend,
> +			 it6505_bridge_resume);
> +
> +#endif
> +
> +static int it6505_init_pdata(struct it6505 *it6505)
> +{
> +	struct it6505_platform_data *pdata = &it6505->pdata;
> +	struct device *dev = &it6505->client->dev;
> +
> +	/* 1.0V digital core power regulator  */
> +	pdata->pwr18 = devm_regulator_get(dev, "pwr18");
> +	if (IS_ERR(pdata->pwr18)) {
> +		DRM_DEV_ERROR(dev, "pwr18 regulator not found");
> +		return PTR_ERR(pdata->pwr18);
> +	}
> +
> +	pdata->ovdd = devm_regulator_get(dev, "ovdd");
> +	if (IS_ERR(pdata->ovdd)) {
> +		DRM_DEV_ERROR(dev, "ovdd regulator not found");
> +		return PTR_ERR(pdata->ovdd);
> +	}
> +
> +	pdata->gpiod_reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(pdata->gpiod_reset)) {
> +		DRM_DEV_ERROR(dev, "gpiod_reset gpio not found");
> +		return PTR_ERR(pdata->gpiod_reset);
> +	}
> +
> +	return 0;
> +}
> +
> +static void it6505_parse_dt(struct it6505 *it6505)
> +{
> +	struct device *dev = &it6505->client->dev;
> +	u32 *afe_setting = &it6505->afe_setting;
> +
> +	it6505->lane_swap_disabled =
> +		device_property_read_bool(dev, "no-laneswap");
> +
> +	if (it6505->lane_swap_disabled)
> +		it6505->lane_swap = false;
> +
> +	if (device_property_read_u32(dev, "afe-setting", afe_setting) == 0) {
> +		if (*afe_setting >= ARRAY_SIZE(afe_setting_table)) {
> +			DRM_DEV_ERROR(dev, "afe setting error, use default");
> +			*afe_setting = 0;
> +		}
> +	} else {
> +		*afe_setting = 0;
> +	}
> +	DRM_DEV_DEBUG_DRIVER(dev, "using afe_setting: %d", *afe_setting);
> +}
> +
> +static ssize_t print_timing_show(struct device *dev,
> +				 struct device_attribute *attr, char *buf)
> +{
> +	struct it6505 *it6505 = dev_get_drvdata(dev);
> +	struct drm_display_mode *vid = &it6505->video_info;
> +	char *str = buf, *end = buf + PAGE_SIZE;
> +
> +	it6505_calc_video_info(it6505);
> +	str += scnprintf(str, end - str, "---video timing---\n");
> +	str += scnprintf(str, end - str, "PCLK:%d.%03dMHz\n",
> +			 vid->clock / 1000, vid->clock % 1000);
> +	str += scnprintf(str, end - str, "HTotal:%d\n", vid->htotal);
> +	str += scnprintf(str, end - str, "HActive:%d\n", vid->hdisplay);
> +	str += scnprintf(str, end - str, "HFrontPorch:%d\n",
> +			 vid->hsync_start - vid->hdisplay);
> +	str += scnprintf(str, end - str, "HSyncWidth:%d\n",
> +			 vid->hsync_end - vid->hsync_start);
> +	str += scnprintf(str, end - str, "HBackPorch:%d\n",
> +			 vid->htotal - vid->hsync_end);
> +	str += scnprintf(str, end - str, "VTotal:%d\n", vid->vtotal);
> +	str += scnprintf(str, end - str, "VActive:%d\n", vid->vdisplay);
> +	str += scnprintf(str, end - str, "VFrontPorch:%d\n",
> +			 vid->vsync_start - vid->vdisplay);
> +	str += scnprintf(str, end - str, "VSyncWidth:%d\n",
> +			 vid->vsync_end - vid->vsync_start);
> +	str += scnprintf(str, end - str, "VBackPorch:%d\n",
> +			 vid->vtotal - vid->vsync_end);
> +
> +	return str - buf;
> +}
> +
> +static ssize_t force_pwronoff_store(struct device *dev,
> +				    struct device_attribute *attr,
> +				    const char *buf, size_t count)
> +{
> +	struct it6505 *it6505 = dev_get_drvdata(dev);
> +	int pwr;
> +
> +	if (kstrtoint(buf, 10, &pwr) < 0)
> +		return -EINVAL;
> +
> +	if (pwr)
> +		it6505_poweron(it6505);
> +	else
> +		it6505_poweroff(it6505);
> +
> +	return count;
> +}
> +
> +static ssize_t enable_drv_hold_show(struct device *dev,
> +				    struct device_attribute *attr, char *buf)
> +{
> +	struct it6505 *it6505 = dev_get_drvdata(dev);
> +
> +	return scnprintf(buf, PAGE_SIZE, "%d\n", it6505->enable_drv_hold);
> +}
> +
> +static ssize_t enable_drv_hold_store(struct device *dev,
> +				     struct device_attribute *attr,
> +				     const char *buf, size_t count)
> +{
> +	struct it6505 *it6505 = dev_get_drvdata(dev);
> +	unsigned int drv_hold;
> +
> +	if (kstrtoint(buf, 10, &drv_hold) < 0)
> +		return -EINVAL;
> +
> +	it6505->enable_drv_hold = !!drv_hold;


Again !!, please just find all occurrences of it an remove them if it is 
assigned to bool type.


> +
> +	if (it6505->enable_drv_hold) {
> +		it6505_int_mask_disable(it6505);
> +	} else {
> +		it6505_clear_int(it6505);
> +		it6505_int_mask_enable(it6505);
> +
> +		if (it6505->powered) {
> +			it6505->connector_status =
> +					it6505_get_sink_hpd_status(it6505) ?
> +					connector_status_connected :
> +					connector_status_disconnected;
> +		} else {
> +			it6505->connector_status =
> +					connector_status_disconnected;
> +		}
> +	}
> +	return count;
> +}
> +
> +static DEVICE_ATTR_RO(print_timing);
> +static DEVICE_ATTR_WO(force_pwronoff);
> +static DEVICE_ATTR_RW(enable_drv_hold);
> +
> +static const struct attribute *it6505_attrs[] = {
> +	&dev_attr_print_timing.attr,
> +	&dev_attr_force_pwronoff.attr,
> +	&dev_attr_enable_drv_hold.attr,
> +	NULL,
> +};
> +
> +static void it6505_shutdown(struct i2c_client *client)
> +{
> +	struct it6505 *it6505 = dev_get_drvdata(&client->dev);
> +
> +	kfree(it6505->edid);
> +	it6505->edid = NULL;
> +
> +	if (it6505->powered)
> +		it6505_lane_off(it6505);
> +}
> +
> +static int it6505_i2c_probe(struct i2c_client *client,
> +			    const struct i2c_device_id *id)
> +{
> +	struct it6505 *it6505;
> +	struct device *dev = &client->dev;
> +	struct extcon_dev *extcon;
> +	int err, intp_irq;
> +
> +	it6505 = devm_kzalloc(&client->dev, sizeof(*it6505), GFP_KERNEL);
> +	if (!it6505)
> +		return -ENOMEM;
> +
> +	mutex_init(&it6505->extcon_lock);
> +	mutex_init(&it6505->mode_lock);
> +	mutex_init(&it6505->aux_lock);
> +
> +	it6505->bridge.of_node = client->dev.of_node;
> +	it6505->connector_status = connector_status_disconnected;
> +	it6505->client = client;
> +	i2c_set_clientdata(client, it6505);
> +
> +	/* get extcon device from DTS */
> +	extcon = extcon_get_edev_by_phandle(dev, 0);
> +	if (PTR_ERR(extcon) == -EPROBE_DEFER)
> +		return -EPROBE_DEFER;
> +	if (IS_ERR(extcon)) {
> +		DRM_DEV_ERROR(dev, "can not get extcon device!");
> +		return PTR_ERR(extcon);
> +	}
> +
> +	it6505->extcon = extcon;
> +
> +	it6505->regmap = devm_regmap_init_i2c(client, &it6505_regmap_config);
> +	if (IS_ERR(it6505->regmap)) {
> +		DRM_DEV_ERROR(dev, "regmap i2c init failed");
> +		err = PTR_ERR(it6505->regmap);
> +		return err;
> +	}
> +
> +	err = it6505_init_pdata(it6505);
> +	if (err) {
> +		DRM_DEV_ERROR(dev, "Failed to initialize pdata: %d", err);
> +		return err;
> +	}
> +
> +	it6505_parse_dt(it6505);
> +
> +	intp_irq = client->irq;
> +
> +	if (!intp_irq) {
> +		DRM_DEV_ERROR(dev, "Failed to get INTP IRQ");
> +		err = -ENODEV;
> +		return err;
> +	}
> +
> +	err = devm_request_threaded_irq(&client->dev, intp_irq, NULL,
> +					it6505_int_threaded_handler,
> +					IRQF_TRIGGER_LOW | IRQF_ONESHOT,
> +					"it6505-intp", it6505);
> +	if (err) {
> +		DRM_DEV_ERROR(dev, "Failed to request INTP threaded IRQ: %d",
> +			      err);
> +		return err;
> +	}
> +
> +	/* Register aux channel */
> +	it6505->aux.name = "DP-AUX";
> +	it6505->aux.dev = dev;
> +	it6505->aux.transfer = it6505_aux_transfer;
> +
> +	err = drm_dp_aux_register(&it6505->aux);
> +	if (err < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to register aux: %d", err);
> +		return err;
> +	}
> +
> +	INIT_WORK(&it6505->link_works, it6505_link_training_work);
> +	INIT_WORK(&it6505->hdcp_wait_ksv_list, it6505_hdcp_wait_ksv_list);
> +	INIT_DELAYED_WORK(&it6505->hdcp_work, it6505_hdcp_work);
> +	init_completion(&it6505->wait_edid_complete);
> +	memset(it6505->dpcd, 0, sizeof(it6505->dpcd));
> +	it6505->powered = false;
> +	it6505->enable_drv_hold = DEFAULT_DRV_HOLD;
> +
> +	if (DEFAULT_PWR_ON)
> +		it6505_poweron(it6505);
> +
> +	err = sysfs_create_files(&client->dev.kobj, it6505_attrs);
> +	if (err) {
> +		drm_dp_aux_unregister(&it6505->aux);
> +		return err;
> +	}
> +
> +	it6505->bridge.funcs = &it6505_bridge_funcs;
> +	drm_bridge_add(&it6505->bridge);
> +
> +	return 0;
> +}
> +
> +static int it6505_i2c_remove(struct i2c_client *client)
> +{
> +	struct it6505 *it6505 = i2c_get_clientdata(client);
> +
> +	drm_connector_unregister(&it6505->connector);
> +	drm_connector_cleanup(&it6505->connector);
> +	drm_bridge_remove(&it6505->bridge);
> +	drm_dp_aux_unregister(&it6505->aux);
> +	sysfs_remove_files(&client->dev.kobj, it6505_attrs);
> +	it6505_poweroff(it6505);
> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id it6505_id[] = {
> +	{ "it6505", 0 },
> +	{ }
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, it6505_id);
> +
> +static const struct of_device_id it6505_of_match[] = {
> +	{ .compatible = "ite,it6505" },
> +	{ }
> +};
> +
> +static struct i2c_driver it6505_i2c_driver = {
> +	.driver = {
> +		.name = "it6505",
> +		.of_match_table = it6505_of_match,
> +#ifdef CONFIG_PM_SLEEP
> +		.pm = &it6505_bridge_pm_ops,
> +#endif
> +	},
> +	.probe = it6505_i2c_probe,
> +	.remove = it6505_i2c_remove,
> +	.shutdown = it6505_shutdown,
> +	.id_table = it6505_id,
> +};
> +
> +module_i2c_driver(it6505_i2c_driver);
> +
> +MODULE_AUTHOR("Allen Chen <allen.chen@xxxxxxxxxx>");
> +MODULE_DESCRIPTION("IT6505 DisplayPort Transmitter driver");
> +MODULE_LICENSE("GPL v2");


The shape of the driver looks OK to me, but it is quite big and 
interacts with many subsystem, so for sure my review was not profound :)

Few more things:

- it would be good to replace some magic numbers inside the code with 
proper macros, all these 0xF0, 0x70, BIT(x) are quite cryptic.

- REG_BANK_SEL is usually at 0, only sometimes is switched to 1, so 
maybe it should be enough to set it to 1 if necessary and then 
immediately set back to 0, as default value, instead of setting it 
multiple times,

- sometimes you are accessing arrays (int status, mask, it6505_dump) 
maybe it would be good to create helpers to read/write arrays to 
simplify the code little bit.


As I said it would be good to get someone's else review, as the driver 
is big.


Regards

Andrzej


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