Re: [PATCH v7 1/4] drm/bridge: add support for sn65dsi86 bridge driver

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On 24.05.2018 18:41, Sandeep Panda wrote:
> Add support for TI's sn65dsi86 dsi2edp bridge chip.
> The chip converts DSI transmitted signal to eDP signal,
> which is fed to the connected eDP panel.
>
> This chip can be controlled via either i2c interface or
> dsi interface. Currently in driver all the control registers
> are being accessed through i2c interface only.
> Also as of now HPD support has not been added to bridge
> chip driver.
>
> Changes in v1:
>  - Split the dt-bindings and the driver support into separate patches
>    (Andrzej Hajda).
>  - Use of gpiod APIs to parse and configure gpios instead of obsolete ones
>    (Andrzej Hajda).
>  - Use macros to define the register offsets (Andrzej Hajda).
>
> Changes in v2:
>  - Separate out edp panel specific HW resource handling from bridge
>    driver and create a separate edp panel drivers to handle panel
>    specific mode information and HW resources (Sean Paul).
>  - Replace pr_* APIs to DRM_* APIs to log error or debug information
>    (Sean Paul).
>  - Remove some of the unnecessary structure/variable from driver (Sean
>    Paul).
>  - Rename the function and structure prefix "sn65dsi86" to "ti_sn_bridge"
>    (Sean Paul / Rob Herring).
>  - Remove most of the hard-coding and modified the bridge init sequence
>    based on current mode (Sean Paul).
>  - Remove the existing function to retrieve the EDID data and
>    implemented this as an i2c_adapter and use drm_get_edid() (Sean Paul).
>  - Remove the dummy irq handler implementation, will add back the
>    proper irq handling later (Sean Paul).
>  - Capture the required enable gpios in a single array based on dt entry
>    instead of having individual descriptor for each gpio (Sean Paul).
>
> Changes in v3:
>  - Remove usage of irq_gpio and replace it as "interrupts" property (Rob
>    Herring).
>  - Remove the unnecessary header file inclusions (Sean Paul).
>  - Rearrange the header files in alphabetical order (Sean Paul).
>  - Use regmap interface to perform i2c transactions.
>  - Update Copyright/License field and address other review comments
>    (Jordan Crouse).
>
> Changes in v4:
>  - Update License/Copyright (Sean Paul).
>  - Add Kconfig and Makefile changes (Sean Paul).
>  - Drop i2c gpio handling from this bridge driver, since i2c sda/scl gpios
>    will be handled by i2c master.
>  - Update required supplies names.
>  - Remove unnecessary goto statements (Sean Paul).
>  - Add mutex lock to power_ctrl API to avoid race conditions (Sean
>    Paul).
>  - Add support to parse reference clk frequency from dt(optional).
>  - Update the bridge chip enable/disable sequence.
>
> Changes in v5:
>  - Fixed Kbuild test service reported warnings.
>
> Changes in v6:
>  - Use PM runtime based ref-counting instead of local ref_count mechanism
>    (Stephen Boyd).
>  - Clean up some debug logs and indentations (Sean Paul).
>  - Simplify dp rate calculation (Sean Paul).
>  - Add support to configure refclk based on input REFCLK pin or DACP/N
>    pin (Stephen Boyd).
>
> Changes in v7:
>  - Use static supply entries instead of dynamic allocation (Andrzej
>    Hajda).
>  - Defer bridge driver probe if panel is not probed (Andrzej Hajda).
>  - Update of_graph APIs for correct node reference management. (Andrzej
>    Hajda).
>  - Remove local display_mode object (Andrzej Hajda).
>  - Remove version id check function from driver.
>
> Signed-off-by: Sandeep Panda <spanda@xxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/bridge/Kconfig        |   9 +
>  drivers/gpu/drm/bridge/Makefile       |   1 +
>  drivers/gpu/drm/bridge/ti-sn65dsi86.c | 675 ++++++++++++++++++++++++++++++++++
>  3 files changed, 685 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/ti-sn65dsi86.c
>
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index 3b99d5a..8153150 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -108,6 +108,15 @@ config DRM_TI_TFP410
>  	---help---
>  	  Texas Instruments TFP410 DVI/HDMI Transmitter driver
>  
> +config DRM_TI_SN65DSI86
> +	tristate "TI SN65DSI86 DSI to eDP bridge"
> +	depends on OF
> +	select DRM_KMS_HELPER
> +	select REGMAP_I2C
> +	select DRM_PANEL
> +	---help---
> +	  Texas Instruments SN65DSI86 DSI to eDP Bridge driver
> +
>  source "drivers/gpu/drm/bridge/analogix/Kconfig"
>  
>  source "drivers/gpu/drm/bridge/adv7511/Kconfig"
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index 373eb28..3711be8 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -12,4 +12,5 @@ obj-$(CONFIG_DRM_TOSHIBA_TC358767) += tc358767.o
>  obj-$(CONFIG_DRM_ANALOGIX_DP) += analogix/
>  obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
>  obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o
> +obj-$(CONFIG_DRM_TI_SN65DSI86) += ti-sn65dsi86.o
>  obj-y += synopsys/
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> new file mode 100644
> index 0000000..3c71789
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> @@ -0,0 +1,675 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2018, The Linux Foundation. All rights reserved.
> + */
> +
> +#include <drm/drmP.h>
> +#include <drm/drm_atomic.h>
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_crtc_helper.h>
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_of.h>
> +#include <drm/drm_panel.h>
> +#include <linux/clk.h>
> +#include <linux/gpio.h>

It is legacy header, linux/gpio/consumer.h should be probably used.

> +#include <linux/i2c.h>
> +#include <linux/of_gpio.h>
I suspect it could be removed as well, to be checked.
> +#include <linux/of_graph.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +
> +/* Link Training specific registers */
> +#define SN_DEVICE_REV_REG			0x08
> +#define SN_HPD_DISABLE_REG			0x5C
> +#define SN_REFCLK_FREQ_REG			0x0A
> +#define SN_DSI_LANES_REG			0x10
> +#define SN_DSIA_CLK_FREQ_REG			0x12
> +#define SN_ENH_FRAME_REG			0x5A
> +#define SN_SSC_CONFIG_REG			0x93
> +#define SN_DATARATE_CONFIG_REG			0x94
> +#define SN_PLL_ENABLE_REG			0x0D
> +#define SN_SCRAMBLE_CONFIG_REG			0x95
> +#define SN_AUX_WDATA0_REG			0x64
> +#define SN_AUX_ADDR_19_16_REG			0x74
> +#define SN_AUX_ADDR_15_8_REG			0x75
> +#define SN_AUX_ADDR_7_0_REG			0x76
> +#define SN_AUX_LENGTH_REG			0x77
> +#define SN_AUX_CMD_REG				0x78
> +#define SN_ML_TX_MODE_REG			0x96
> +/* video config specific registers */
> +#define SN_CHA_ACTIVE_LINE_LENGTH_LOW_REG	0x20
> +#define SN_CHA_ACTIVE_LINE_LENGTH_HIGH_REG	0x21
> +#define SN_CHA_VERTICAL_DISPLAY_SIZE_LOW_REG	0x24
> +#define SN_CHA_VERTICAL_DISPLAY_SIZE_HIGH_REG	0x25
> +#define SN_CHA_HSYNC_PULSE_WIDTH_LOW_REG	0x2C
> +#define SN_CHA_HSYNC_PULSE_WIDTH_HIGH_REG	0x2D
> +#define SN_CHA_VSYNC_PULSE_WIDTH_LOW_REG	0x30
> +#define SN_CHA_VSYNC_PULSE_WIDTH_HIGH_REG	0x31
> +#define SN_CHA_HORIZONTAL_BACK_PORCH_REG	0x34
> +#define SN_CHA_VERTICAL_BACK_PORCH_REG		0x36
> +#define SN_CHA_HORIZONTAL_FRONT_PORCH_REG	0x38
> +#define SN_CHA_VERTICAL_FRONT_PORCH_REG		0x3A
> +#define SN_DATA_FORMAT_REG			0x5B
> +
> +#define MIN_DSI_CLK_FREQ_MHZ	40
> +
> +/* fudge factor required to account for 8b/10b encoding */
> +#define DP_CLK_FUDGE_NUM	10
> +#define DP_CLK_FUDGE_DEN	8
> +
> +#define DPPLL_CLK_SRC_REFCLK	0
> +#define DPPLL_CLK_SRC_DSICLK	1
> +
> +#define SN_DSIA_REFCLK_OFFSET	1
> +#define SN_DSIA_LANE_OFFSET	3
> +#define SN_DP_LANE_OFFSET	4
> +#define SN_DP_DATA_RATE_OFFSET	5
> +#define SN_TIMING_HIGH_OFFSET	8

>From the code it looks like it is just number of bits in byte, so you
can drop it and use 8 instead.

> +
> +#define SN_ENABLE_VID_STREAM_BIT	BIT(3)
> +#define SN_DSIA_NUM_LANES_BITS		(BIT(4) | BIT(3))
> +#define SN_DP_NUM_LANES_BITS		(BIT(5) | BIT(4))
> +#define SN_DP_DATA_RATE_BITS		(BIT(7) | BIT(6) | BIT(5))
> +#define SN_HPD_DISABLE_BIT		BIT(0)
> +
> +#define SN_REGULATOR_SUPPLY_NUM		4
> +
> +struct ti_sn_bridge {
> +	struct device			*dev;
> +	struct regmap			*regmap;
> +	struct drm_bridge		bridge;
> +	struct drm_connector		connector;
> +	struct device_node		*host_node;
> +	struct mipi_dsi_device		*dsi;
> +	struct clk			*refclk;
> +	struct drm_panel		*panel;
> +	struct gpio_desc		*enable_gpio;
> +	struct regulator_bulk_data	supplies[SN_REGULATOR_SUPPLY_NUM];
> +	struct i2c_adapter		*ddc;
> +};
> +
> +static const struct regmap_range ti_sn_bridge_volatile_ranges[] = {
> +	{ .range_min = 0, .range_max = 0xff },
> +};
> +
> +static const struct regmap_access_table ti_sn_bridge_volatile_table = {
> +	.yes_ranges = ti_sn_bridge_volatile_ranges,
> +	.n_yes_ranges = ARRAY_SIZE(ti_sn_bridge_volatile_ranges),
> +};
> +
> +static const struct regmap_config ti_sn_bridge_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.volatile_table = &ti_sn_bridge_volatile_table,
> +	.cache_type = REGCACHE_NONE,
> +};
> +
> +static int __maybe_unused ti_sn_bridge_resume(struct device *dev)
> +{
> +	struct ti_sn_bridge *pdata = dev_get_drvdata(dev);
> +	int ret = 0;
> +
> +	ret = regulator_bulk_enable(SN_REGULATOR_SUPPLY_NUM, pdata->supplies);
> +	if (ret) {
> +		DRM_ERROR("failed to enable supplies %d\n", ret);
> +		return ret;
> +	}
> +
> +	gpiod_set_value(pdata->enable_gpio, 1);
> +
> +	return ret;
> +}
> +
> +static int __maybe_unused ti_sn_bridge_suspend(struct device *dev)
> +{
> +	struct ti_sn_bridge *pdata = dev_get_drvdata(dev);
> +	int ret = 0;
> +
> +	gpiod_set_value(pdata->enable_gpio, 0);
> +
> +	ret = regulator_bulk_disable(SN_REGULATOR_SUPPLY_NUM, pdata->supplies);
> +	if (ret)
> +		DRM_ERROR("failed to disable supplies %d\n", ret);
> +
> +	return ret;
> +}
> +
> +static const struct dev_pm_ops ti_sn_bridge_pm_ops = {
> +	SET_RUNTIME_PM_OPS(ti_sn_bridge_suspend, ti_sn_bridge_resume, NULL)
> +};
> +
> +/* Connector funcs */
> +static struct ti_sn_bridge *
> +connector_to_ti_sn_bridge(struct drm_connector *connector)
> +{
> +	return container_of(connector, struct ti_sn_bridge, connector);
> +}
> +
> +static int ti_sn_bridge_connector_get_modes(struct drm_connector *connector)
> +{
> +	struct ti_sn_bridge *pdata = connector_to_ti_sn_bridge(connector);
> +	struct edid *edid;
> +	u32 num_modes;
> +
> +	if (pdata->panel) {
> +		DRM_DEBUG_KMS("get mode from connected drm_panel\n");
> +		return drm_panel_get_modes(pdata->panel);
> +	}
> +
> +	if (!pdata->ddc)
> +		return 0;
> +
> +	pm_runtime_get_sync(pdata->dev);
> +	edid = drm_get_edid(connector, pdata->ddc);
> +	pm_runtime_put_sync(pdata->dev);
> +	if (!edid)
> +		return 0;
> +
> +	drm_mode_connector_update_edid_property(connector, edid);
> +	num_modes = drm_add_edid_modes(connector, edid);
> +	kfree(edid);
> +
> +	return num_modes;
> +}
> +
> +static enum drm_mode_status
> +ti_sn_bridge_connector_mode_valid(struct drm_connector *connector,
> +			     struct drm_display_mode *mode)
> +{
> +	/* maximum supported resolution is 4K at 60 fps */
> +	if (mode->clock > 594000)
> +		return MODE_CLOCK_HIGH;

I wonder if training results shouldn't be taken into account.

> +
> +	return MODE_OK;
> +}
> +
> +static struct drm_connector_helper_funcs ti_sn_bridge_connector_helper_funcs = {
> +	.get_modes = ti_sn_bridge_connector_get_modes,
> +	.mode_valid = ti_sn_bridge_connector_mode_valid,
> +};
> +
> +static enum drm_connector_status
> +ti_sn_bridge_connector_detect(struct drm_connector *connector, bool force)
> +{
> +	struct ti_sn_bridge *pdata = connector_to_ti_sn_bridge(connector);
> +
> +	/**
> +	 * TODO: Currently if drm_panel is present, then always
> +	 * return the status as connected. Need to add support to detect
> +	 * device state for no panel(hot pluggable) scenarios.
> +	 */
> +	if (pdata->panel)
> +		return connector_status_connected;
> +	else
> +		return connector_status_unknown;
> +}
> +
> +static const struct drm_connector_funcs ti_sn_bridge_connector_funcs = {
> +	.fill_modes = drm_helper_probe_single_connector_modes,
> +	.detect = ti_sn_bridge_connector_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 struct ti_sn_bridge *bridge_to_ti_sn_bridge(struct drm_bridge *bridge)
> +{
> +	return container_of(bridge, struct ti_sn_bridge, bridge);
> +}
> +
> +static const char * const ti_sn_bridge_supply_names[] = {
> +	"vcca",
> +	"vcc",
> +	"vccio",
> +	"vpll",
> +};

If you use this array only in following function, you can put the
definition there.

> +
> +static int ti_sn_bridge_parse_regulators(struct ti_sn_bridge *pdata)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < SN_REGULATOR_SUPPLY_NUM; i++)
> +		pdata->supplies[i].supply = ti_sn_bridge_supply_names[i];
> +
> +	return devm_regulator_bulk_get(pdata->dev, SN_REGULATOR_SUPPLY_NUM,
> +				       pdata->supplies);
> +}
> +
> +static int ti_sn_bridge_attach(struct drm_bridge *bridge)
> +{
> +	struct mipi_dsi_host *host;
> +	struct mipi_dsi_device *dsi;
> +	struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);
> +	int ret;
> +	const struct mipi_dsi_device_info info = { .type = "ti_sn_bridge",
> +						   .channel = 0,
> +						   .node = NULL,
> +						 };
> +
> +	if (!bridge->encoder) {
> +		DRM_ERROR("Parent encoder object not found\n");
> +		return -ENODEV;
> +	}

drm_bridge_attach assures it wont happen, so you can remove the check above.

> +
> +	ret = drm_connector_init(bridge->dev, &pdata->connector,
> +				 &ti_sn_bridge_connector_funcs,
> +				 DRM_MODE_CONNECTOR_eDP);
> +	if (ret) {
> +		DRM_ERROR("Failed to initialize connector with drm\n");
> +		return ret;
> +	}
> +
> +	drm_connector_helper_add(&pdata->connector,
> +				 &ti_sn_bridge_connector_helper_funcs);
> +	drm_mode_connector_attach_encoder(&pdata->connector, bridge->encoder);
> +
> +	host = of_find_mipi_dsi_host_by_node(pdata->host_node);
> +	if (!host) {
> +		DRM_ERROR("failed to find dsi host\n");
> +		return -ENODEV;
> +	}

Hmm, this is resource, so it should be rather acquired in probe
(together with dsi dev register), is there a reason to put it here?
If it must be here you should undo things on all below error paths
(drm_connector_cleanup).

> +
> +	dsi = mipi_dsi_device_register_full(host, &info);
> +	if (IS_ERR(dsi)) {
> +		DRM_ERROR("failed to create dsi device\n");
> +		ret = PTR_ERR(dsi);
> +		return ret;
> +	}
> +
> +	/* TODO: setting to 4 lanes always for now */
> +	dsi->lanes = 4;
> +	dsi->format = MIPI_DSI_FMT_RGB888;
> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_SYNC_PULSE |
> +			  MIPI_DSI_MODE_EOT_PACKET | MIPI_DSI_MODE_VIDEO_HSE;
> +
> +	ret = mipi_dsi_attach(dsi);
> +	if (ret < 0) {
> +		DRM_ERROR("failed to attach dsi to host\n");
> +		mipi_dsi_device_unregister(dsi);
> +		return ret;
> +	}
> +
> +	pdata->dsi = dsi;
> +
> +	DRM_DEBUG_KMS("ti_sn_bridge attached to dsi\n");
> +	/* attach panel to bridge */
> +	if (pdata->panel)
> +		drm_panel_attach(pdata->panel, &pdata->connector);
> +
> +	return 0;
> +}
> +
> +static void ti_sn_bridge_disable(struct drm_bridge *bridge)
> +{
> +	struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);
> +
> +	if (pdata->panel) {
> +		drm_panel_disable(pdata->panel);
> +		drm_panel_unprepare(pdata->panel);
> +	}
> +
> +	/* disable video stream */
> +	regmap_update_bits(pdata->regmap, SN_ENH_FRAME_REG,
> +			   SN_ENABLE_VID_STREAM_BIT, 0);
> +	/* semi auto link training mode OFF */
> +	regmap_write(pdata->regmap, SN_ML_TX_MODE_REG, 0);
> +	/* disable DP PLL */
> +	regmap_write(pdata->regmap, SN_PLL_ENABLE_REG, 0);
> +}
> +
> +static u32 ti_sn_bridge_get_dsi_freq(struct ti_sn_bridge *pdata)
> +{
> +	u32 bit_rate_khz, clk_freq_khz;
> +	struct drm_display_mode *mode =
> +		&pdata->bridge.encoder->crtc->state->adjusted_mode;
> +
> +	bit_rate_khz = mode->clock *
> +			mipi_dsi_pixel_format_to_bpp(pdata->dsi->format);
> +	clk_freq_khz = bit_rate_khz / (pdata->dsi->lanes * 2);
> +
> +	return clk_freq_khz;
> +}
> +
> +#define REFCLK_LUT_SIZE	5
> +
> +/* clk frequencies supported by bridge in Hz in case derived from REFCLK pin */
> +static const u32 ti_sn_bridge_refclk_lut[] = {
> +	12000000,
> +	19200000,
> +	26000000,
> +	27000000,
> +	38400000,
> +};
> +
> +/* clk frequencies supported by bridge in Hz in case derived from DACP/N pin */
> +static const u32 ti_sn_bridge_dsiclk_lut[] = {
> +	468000000,
> +	384000000,
> +	416000000,
> +	486000000,
> +	460800000,
> +};
> +
> +static void ti_sn_bridge_set_refclk(struct ti_sn_bridge *pdata)
> +{
> +	int i = 0;
> +	u8 refclk_src;
> +	u32 refclk_rate;
> +	const u32 *refclk_lut;
> +
> +	if (pdata->refclk) {
> +		refclk_src = DPPLL_CLK_SRC_REFCLK;
> +		refclk_rate = clk_get_rate(pdata->refclk);
> +		refclk_lut = ti_sn_bridge_refclk_lut;
> +		clk_prepare_enable(pdata->refclk);
> +	} else {
> +		refclk_src = DPPLL_CLK_SRC_DSICLK;
> +		refclk_rate = ti_sn_bridge_get_dsi_freq(pdata) * 1000;
> +		refclk_lut = ti_sn_bridge_dsiclk_lut;
> +	}
> +
> +	/* for i equals to REFCLK_LUT_SIZE means default frequency */
> +	for (i = 0; i < REFCLK_LUT_SIZE; i++)
> +		if (refclk_lut[i] == refclk_rate)
> +			break;
> +
> +	regmap_write(pdata->regmap, SN_REFCLK_FREQ_REG,
> +		     (refclk_src | (i << SN_DSIA_REFCLK_OFFSET)));
> +}
> +
> +/**
> + * LUT index corresponds to register value and
> + * LUT values corresponds to dp data rate supported
> + * by the bridge in Mbps unit.
> + */
> +static const unsigned int ti_sn_bridge_dp_rate_lut[] = {
> +	0, 1620, 2160, 2430, 2700, 3240, 4320, 5400
> +};
> +
> +static void ti_sn_bridge_set_dsi_dp_rate(struct ti_sn_bridge *pdata)
> +{
> +	unsigned int bit_rate_mhz, clk_freq_mhz, dp_rate_mhz;
> +	unsigned int val = 0, i = 0;
> +	struct drm_display_mode *mode =
> +		&pdata->bridge.encoder->crtc->state->adjusted_mode;
> +
> +	/* set DSIA clk frequency */
> +	bit_rate_mhz = (mode->clock / 1000) *
> +			mipi_dsi_pixel_format_to_bpp(pdata->dsi->format);
> +	clk_freq_mhz = bit_rate_mhz / (pdata->dsi->lanes * 2);
> +
> +	/* for each increment in val, frequency increases by 5MHz */
> +	val = (MIN_DSI_CLK_FREQ_MHZ / 5) +
> +		(((clk_freq_mhz - MIN_DSI_CLK_FREQ_MHZ) / 5) & 0xFF);
> +	regmap_write(pdata->regmap, SN_DSIA_CLK_FREQ_REG, val);
> +
> +	/* set DP data rate */
> +	dp_rate_mhz = ((bit_rate_mhz / pdata->dsi->lanes) * DP_CLK_FUDGE_NUM) /
> +							DP_CLK_FUDGE_DEN;
> +	for (i = 0; i < ARRAY_SIZE(ti_sn_bridge_dp_rate_lut) - 1; i++)
> +		if (ti_sn_bridge_dp_rate_lut[i] > dp_rate_mhz)
> +			break;
> +
> +	regmap_update_bits(pdata->regmap, SN_DATARATE_CONFIG_REG,
> +			   SN_DP_DATA_RATE_BITS, i << SN_DP_DATA_RATE_OFFSET);
> +}
> +
> +static void ti_sn_bridge_set_video_timings(struct ti_sn_bridge *pdata)
> +{
> +	struct drm_display_mode *mode =
> +		&pdata->bridge.encoder->crtc->state->adjusted_mode;
> +
> +	regmap_write(pdata->regmap, SN_CHA_ACTIVE_LINE_LENGTH_LOW_REG,
> +		     mode->hdisplay & 0xFF);
> +	regmap_write(pdata->regmap, SN_CHA_ACTIVE_LINE_LENGTH_HIGH_REG,
> +		     (mode->hdisplay >> SN_TIMING_HIGH_OFFSET) & 0xFF);

Since you have multiple writes of 16bit words into consecutive registers
you can create helper to make it more readable, for example:
void ti_sn_bridge_write_u16(struct ti_sn_bridge *pdata, unsigned int
reg, u16 val)
{
    regmap_write(pdata->regmap, reg, val & 0xff);
    regmap_write(pdata->regmap, reg + 1, val >> 8);
}

> +	regmap_write(pdata->regmap, SN_CHA_VERTICAL_DISPLAY_SIZE_LOW_REG,
> +		     mode->vdisplay & 0xFF);
> +	regmap_write(pdata->regmap, SN_CHA_VERTICAL_DISPLAY_SIZE_HIGH_REG,
> +		     (mode->vdisplay >> SN_TIMING_HIGH_OFFSET) & 0xFF);
> +	regmap_write(pdata->regmap, SN_CHA_HSYNC_PULSE_WIDTH_LOW_REG,
> +		     (mode->hsync_end - mode->hsync_start) & 0xFF);
> +	regmap_write(pdata->regmap, SN_CHA_HSYNC_PULSE_WIDTH_HIGH_REG,
> +		     ((mode->hsync_end - mode->hsync_start) >>
> +		      SN_TIMING_HIGH_OFFSET) & 0xFF);
> +	regmap_write(pdata->regmap, SN_CHA_VSYNC_PULSE_WIDTH_LOW_REG,
> +		     (mode->vsync_end - mode->vsync_start) & 0xFF);
> +	regmap_write(pdata->regmap, SN_CHA_VSYNC_PULSE_WIDTH_HIGH_REG,
> +		     ((mode->vsync_end - mode->vsync_start) >>
> +		      SN_TIMING_HIGH_OFFSET) & 0xFF);
> +	regmap_write(pdata->regmap, SN_CHA_HORIZONTAL_BACK_PORCH_REG,
> +		     (mode->htotal - mode->hsync_end) & 0xFF);
> +	regmap_write(pdata->regmap, SN_CHA_VERTICAL_BACK_PORCH_REG,
> +		     (mode->vtotal - mode->vsync_end) & 0xFF);
> +	regmap_write(pdata->regmap, SN_CHA_HORIZONTAL_FRONT_PORCH_REG,
> +		     (mode->hsync_start - mode->hdisplay) & 0xFF);
> +	regmap_write(pdata->regmap, SN_CHA_VERTICAL_FRONT_PORCH_REG,
> +		     (mode->vsync_start - mode->vdisplay) & 0xFF);
> +	usleep_range(10000, 10500); /* 10ms delay recommended by spec */
> +}
> +
> +static void ti_sn_bridge_enable(struct drm_bridge *bridge)
> +{
> +	struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);
> +	unsigned int val = 0;
> +
> +	if (pdata->panel) {
> +		drm_panel_prepare(pdata->panel);
> +		/* in case drm_panel is connected then HPD is not supported */
> +		regmap_update_bits(pdata->regmap, SN_HPD_DISABLE_REG,
> +				   SN_HPD_DISABLE_BIT, SN_HPD_DISABLE_BIT);

		regmap_update_bits(pdata->regmap, SN_HPD_DISABLE_REG,
				   SN_HPD_DISABLE_BIT, ~0);
 

> +	}
> +
> +	/* DSI_A lane config */
> +	val = (4 - pdata->dsi->lanes) << SN_DSIA_LANE_OFFSET;
> +	regmap_update_bits(pdata->regmap, SN_DSI_LANES_REG,
> +			   SN_DSIA_NUM_LANES_BITS, val);
> +
> +	/* DP lane config */
> +	val = (pdata->dsi->lanes - 1) << SN_DP_LANE_OFFSET;
> +	regmap_update_bits(pdata->regmap, SN_SSC_CONFIG_REG,
> +			   SN_DP_NUM_LANES_BITS, val);
> +
> +	/* set dsi/dp clk frequency value */
> +	ti_sn_bridge_set_dsi_dp_rate(pdata);
> +
> +	/* enable DP PLL */
> +	regmap_write(pdata->regmap, SN_PLL_ENABLE_REG, 1);
> +	usleep_range(10000, 10500); /* 10ms delay recommended by spec */
> +
> +	/**
> +	 * The SN65DSI86 only supports ASSR Display Authentication method and
> +	 * this method is enabled by default. An eDP panel must support this
> +	 * authentication method. We need to enable this method in the eDP panel
> +	 * at DisplayPort address 0x0010A prior to link training.
> +	 */
> +	regmap_write(pdata->regmap, SN_AUX_WDATA0_REG, 0x01);
> +	regmap_write(pdata->regmap, SN_AUX_ADDR_19_16_REG, 0x00);
> +	regmap_write(pdata->regmap, SN_AUX_ADDR_15_8_REG, 0x01);
> +	regmap_write(pdata->regmap, SN_AUX_ADDR_7_0_REG, 0x0A);
> +	regmap_write(pdata->regmap, SN_AUX_LENGTH_REG, 0x01);
> +	regmap_write(pdata->regmap, SN_AUX_CMD_REG, 0x81);
> +	usleep_range(10000, 10500); /* 10ms delay recommended by spec */
> +
> +	/* Semi auto link training mode */
> +	regmap_write(pdata->regmap, SN_ML_TX_MODE_REG, 0x0A);
> +	msleep(20); /* 20ms delay recommended by spec */
> +
> +	/* config video parameters */
> +	ti_sn_bridge_set_video_timings(pdata);
> +
> +	/* enable video stream */
> +	regmap_update_bits(pdata->regmap, SN_ENH_FRAME_REG,
> +			   SN_ENABLE_VID_STREAM_BIT, SN_ENABLE_VID_STREAM_BIT);
> +
> +	if (pdata->panel)
> +		drm_panel_enable(pdata->panel);
> +}
> +
> +static void ti_sn_bridge_pre_enable(struct drm_bridge *bridge)
> +{
> +	struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);
> +
> +	pm_runtime_get_sync(pdata->dev);
> +
> +	/* configure bridge CLK_SRC and ref_clk */
> +	ti_sn_bridge_set_refclk(pdata);
> +}
> +
> +static void ti_sn_bridge_post_disable(struct drm_bridge *bridge)
> +{
> +	struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);
> +
> +	if (pdata->refclk)
> +		clk_disable_unprepare(pdata->refclk);
> +
> +	pm_runtime_put_sync(pdata->dev);
> +}
> +
> +static const struct drm_bridge_funcs ti_sn_bridge_funcs = {
> +	.attach = ti_sn_bridge_attach,
> +	.pre_enable = ti_sn_bridge_pre_enable,
> +	.enable = ti_sn_bridge_enable,
> +	.disable = ti_sn_bridge_disable,
> +	.post_disable = ti_sn_bridge_post_disable,
> +};
> +
> +static int ti_sn_bridge_parse_dsi_host(struct ti_sn_bridge *pdata)
> +{
> +	struct device_node *np = pdata->dev->of_node;
> +
> +	pdata->host_node = of_graph_get_remote_node(np, 0, 0);
> +
> +	if (!pdata->host_node) {
> +		DRM_ERROR("remote dsi host node not found\n");
> +		return -ENODEV;
> +	}
> +	of_node_put(pdata->host_node);
of_node_put should be called in remove.
> +
> +	return 0;
> +}
> +
> +static int ti_sn_bridge_probe(struct i2c_client *client,
> +	 const struct i2c_device_id *id)
> +{
> +	struct ti_sn_bridge *pdata;
> +	struct device_node *ddc_node;
> +	int ret = 0;
> +
> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
> +		DRM_ERROR("device doesn't support I2C\n");
> +		return -ENODEV;
> +	}
> +
> +	pdata = devm_kzalloc(&client->dev, sizeof(struct ti_sn_bridge),
> +			     GFP_KERNEL);
> +	if (!pdata)
> +		return -ENOMEM;
> +
> +	pdata->dev = &client->dev;
> +	dev_set_drvdata(&client->dev, pdata);
> +
> +	ret = drm_of_find_panel_or_bridge(pdata->dev->of_node, 1, 0,
> +					  &pdata->panel, NULL);
> +	if (ret) {
> +		DRM_ERROR("could not find any drm panel node\n");
> +		return ret;
> +	}
> +
> +	pdata->regmap = devm_regmap_init_i2c(client,
> +					     &ti_sn_bridge_regmap_config);
> +	if (IS_ERR(pdata->regmap)) {
> +		DRM_ERROR("regmap i2c init failed\n");
> +		return PTR_ERR(pdata->regmap);
> +	}
> +
> +	pdata->enable_gpio = devm_gpiod_get(pdata->dev,
> +					    "enable", GPIOD_OUT_LOW);
> +	if (IS_ERR(pdata->enable_gpio)) {
> +		DRM_ERROR("failed to get enable gpio from DT\n");
> +		ret = PTR_ERR(pdata->enable_gpio);
> +		return ret;
> +	}
> +
> +	ret = ti_sn_bridge_parse_regulators(pdata);
> +	if (ret) {
> +		DRM_ERROR("failed to parse regulators\n");
> +		return ret;
> +	}
> +
> +	ret = ti_sn_bridge_parse_dsi_host(pdata);
> +	if (ret)
> +		return ret;
> +
> +	pm_runtime_enable(pdata->dev);
> +
> +	pdata->refclk = devm_clk_get(pdata->dev, "refclk");
> +
> +	ddc_node = of_parse_phandle(pdata->dev->of_node, "ddc-i2c-bus", 0);

ddc-i2c-bus is not documented in bindings.

> +	if (ddc_node) {
> +		pdata->ddc = of_find_i2c_adapter_by_node(ddc_node);
> +		of_node_put(ddc_node);
> +		if (!pdata->ddc) {
> +			DRM_DEBUG_KMS("failed to read ddc node\n");
> +			pm_runtime_disable(pdata->dev);
> +			return -EPROBE_DEFER;
> +		}
> +	} else {
> +		DRM_DEBUG_KMS("no ddc property found\n");
> +	}

 If you put pm_runtime_enable after 'if', you can remove
pm_runtime_disable above.

> +
> +	i2c_set_clientdata(client, pdata);
> +
> +	pdata->bridge.funcs = &ti_sn_bridge_funcs;
> +	pdata->bridge.of_node = client->dev.of_node;
> +
> +	drm_bridge_add(&pdata->bridge);
> +
> +	return 0;
> +}
> +
> +static int ti_sn_bridge_remove(struct i2c_client *client)
> +{
> +	struct ti_sn_bridge *pdata = i2c_get_clientdata(client);
> +
> +	if (!pdata)
> +		return -EINVAL;
> +
> +	mipi_dsi_detach(pdata->dsi);
> +	mipi_dsi_device_unregister(pdata->dsi);

dsi attach and register are performed in panel attach callback, this is
asymmetric and can cause oops if bridge is unbind before attaching, as I
said earlier please consider moving dsi attach/register to probe.

Regards
Andrzej

> +
> +	drm_bridge_remove(&pdata->bridge);
> +	pm_runtime_disable(pdata->dev);
> +	i2c_put_adapter(pdata->ddc);
> +
> +	return 0;
> +}
> +
> +static struct i2c_device_id ti_sn_bridge_id[] = {
> +	{ "ti,sn65dsi86", 0},
> +	{},
> +};
> +MODULE_DEVICE_TABLE(i2c, ti_sn_bridge_id);
> +
> +static const struct of_device_id ti_sn_bridge_match_table[] = {
> +	{.compatible = "ti,sn65dsi86"},
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, ti_sn_bridge_match_table);
> +
> +static struct i2c_driver ti_sn_bridge_driver = {
> +	.driver = {
> +		.name = "ti_sn65dsi86",
> +		.of_match_table = ti_sn_bridge_match_table,
> +		.pm = &ti_sn_bridge_pm_ops,
> +	},
> +	.probe = ti_sn_bridge_probe,
> +	.remove = ti_sn_bridge_remove,
> +	.id_table = ti_sn_bridge_id,
> +};
> +
> +module_i2c_driver(ti_sn_bridge_driver);
> +MODULE_DESCRIPTION("sn65dsi86 DSI to eDP bridge driver");
> +MODULE_LICENSE("GPL v2");


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