Re: [PATCH] drm/i915: Backlight Control over AUX feature

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On Thu, Sep 10, 2015 at 03:11:42PM +0100, Yetunde Adebisi wrote:
> This patch adds support for Backlight Control over the AUX channel for
> DP and eDP connectors. It allows the backlight of DP and eDP connected
> displays to be controlled from software using sysfs interface.
> 
> The code first checks if the DP/eDP display has the capability for
> backlight control by reading Display Control DPCD registers as defined
> by the eDP v1.3 VESA specs.
> It then registers a /sys/backlight device if backlight control is
> supported.
> 
> It provides functions to
> - Register a sysfs backlight interface if the eDP/DP connnector is
> capable of aux backlight control
> - Read the current backlight level from DPCD register 0x722
> - Change the backlight level
> - Disable/Enable the backlight by writing to DPCD register 0x720
> 
> Usage:
> Backlight level ranges from 0(min)-240(max) 0x0-0xF0
> - To change Backlight level to 50
> echo 50 > /sys/class/backlight/intel_aux_backlight-DP-3/brightness
> 
> - To disable backlight
> echo 4 > /sys/class/backlight/intel_aux_backlight-DP-3/bl_power
> - To enable backlight
> echo 0 > /sys/class/backlight/intel_aux_backlight-DP-3/bl_power
> 
> v2:
> - Code clean up
> - Avoid code duplication by merging the backlight device
>  register/unregister function with the existing one for internal displays
> 
> v3:
> Further changes to re-use existing code by adding bl_name and backlight_ops
> variables to the intel_backlight structure.
> 
> Cc: Bob Paauwe <bob.j.paauwe@xxxxxxxxx>
> Signed-off-by: Yetunde Adebisi <yetundex.adebisi@xxxxxxxxx>
> ---
>  drivers/gpu/drm/i915/Makefile                     |   1 +
>  drivers/gpu/drm/i915/intel_display.c              |   1 +
>  drivers/gpu/drm/i915/intel_dp.c                   |   6 +-
>  drivers/gpu/drm/i915/intel_dp_aux_backlight_ctl.c | 324 ++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_drv.h                  |  46 ++-
>  drivers/gpu/drm/i915/intel_panel.c                | 111 +++++---
>  include/drm/drm_dp_helper.h                       |   6 +
>  7 files changed, 443 insertions(+), 52 deletions(-)
>  create mode 100644 drivers/gpu/drm/i915/intel_dp_aux_backlight_ctl.c
> 
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index 44d290a..260be03 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -77,6 +77,7 @@ i915-y += dvo_ch7017.o \
>  	  dvo_tfp410.o \
>  	  intel_crt.o \
>  	  intel_ddi.o \
> +	  intel_dp_aux_backlight_ctl.o \

Shouldn't we have most of this implemented as a generic helper on top of
the core drm_dp_aux abstraction in the drm_dp_helper.c code? And drivers
would then just call the overall backlight_register/unregister functions
provided by those helpers.

The other bit from my high-level review is that the kerneldoc needs more
polish and needs to be pulled into drm.tmpl at a suitable place.
-Daniel

>  	  intel_dp_mst.o \
>  	  intel_dp.o \
>  	  intel_dsi.o \
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index e629a1b..2937432 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -15340,6 +15340,7 @@ void intel_connector_unregister(struct intel_connector *intel_connector)
>  	struct drm_connector *connector = &intel_connector->base;
>  
>  	intel_panel_destroy_backlight(connector);
> +	intel_dp_aux_backlight_destroy(connector);
>  	drm_connector_unregister(connector);
>  }
>  
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 45ab25e..975a836 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -3018,7 +3018,7 @@ static void chv_dp_post_pll_disable(struct intel_encoder *encoder)
>   * Sinks are *supposed* to come up within 1ms from an off state, but we're also
>   * supposed to retry 3 times per the spec.
>   */
> -static ssize_t
> +ssize_t
>  intel_dp_dpcd_read_wake(struct drm_dp_aux *aux, unsigned int offset,
>  			void *buffer, size_t size)
>  {
> @@ -3969,7 +3969,7 @@ intel_dp_link_down(struct intel_dp *intel_dp)
>  	msleep(intel_dp->panel_power_down_delay);
>  }
>  
> -static bool
> +bool
>  intel_dp_get_dpcd(struct intel_dp *intel_dp)
>  {
>  	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
> @@ -6125,6 +6125,8 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
>  		return false;
>  	}
>  
> +	intel_dp_aux_backlight_init(intel_dp, connector);
> +
>  	intel_dp_add_properties(intel_dp, connector);
>  
>  	/* For G4X desktop chip, PEG_BAND_GAP_DATA 3:0 must first be written
> diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight_ctl.c b/drivers/gpu/drm/i915/intel_dp_aux_backlight_ctl.c
> new file mode 100644
> index 0000000..a8ef960
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight_ctl.c
> @@ -0,0 +1,324 @@
> +/*
> + * Copyright © 2015 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + *
> + *
> + */
> +
> +#include "intel_drv.h"
> +
> +
> +#define MAX_AUX_BL_HW_LEVEL 0xF0
> +#define MIN_AUX_BL_HW_LEVEL 0x00
> +
> +
> +static uint8_t read_mode_set_reg(struct intel_dp *intel_dp)
> +{
> +	uint8_t dpcd_buf = 0;
> +
> +	if (intel_dp_dpcd_read_wake(&intel_dp->aux,
> +			DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
> +			&dpcd_buf, sizeof(dpcd_buf)) < 0)
> +		DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
> +				DP_EDP_BACKLIGHT_MODE_SET_REGISTER);
> +
> +	return dpcd_buf;
> +}
> +
> +/**
> + * Read the current backlight value from DPCD register(s) based
> + * on if 8-bit(MSB) or 16-bit(MSB and LSB) values are supported
> + */
> +static uint16_t read_aux_backlight_level(struct intel_dp *intel_dp)
> +{
> +	uint16_t read_val = 0;
> +
> +	if (intel_dp_dpcd_read_wake(&intel_dp->aux,
> +			DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
> +			&read_val, sizeof(read_val)) < 0) {
> +		DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
> +				DP_EDP_BACKLIGHT_BRIGHTNESS_MSB);
> +		return 0;
> +	}
> +	if (intel_dp->aux_backlight.use_lsb_reg) {
> +		uint8_t val_lsb = 0;
> +
> +		if (intel_dp_dpcd_read_wake(&intel_dp->aux,
> +				DP_EDP_BACKLIGHT_BRIGHTNESS_LSB,
> +				&val_lsb, sizeof(val_lsb)) < 0) {
> +			DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
> +					DP_EDP_BACKLIGHT_BRIGHTNESS_LSB);
> +			return 0;
> +		}
> +		read_val = (read_val << 8 | val_lsb);
> +	}
> +
> +	return read_val;
> +}
> +
> +
> +static bool get_aux_backlight_enable(struct drm_dp_aux *aux)
> +{
> +	uint8_t read_val = 0;
> +
> +	if (intel_dp_dpcd_read_wake(aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
> +			&read_val, sizeof(read_val)) < 0) {
> +		DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
> +				DP_EDP_DISPLAY_CONTROL_REGISTER);
> +		}
> +	return read_val & DP_EDP_BACKLIGHT_ENABLE;
> +}
> +
> +
> +static bool is_aux_display_control_capable(struct drm_connector *connector)
> +{
> +	struct intel_encoder *intel_encoder = intel_attached_encoder(connector);
> +	struct intel_dp *intel_dp = enc_to_intel_dp(&intel_encoder->base);
> +	uint8_t dpcd_edp[2] = { 0x0 };
> +
> +	/* Check the  eDP Display control capabilities registers to determine if
> +	 * the panel can support backlight control over the aux channel*/
> +	if (intel_dp_dpcd_read_wake(&intel_dp->aux, DP_EDP_GENERAL_CAP_1,
> +			dpcd_edp, sizeof(dpcd_edp)) < 0) {
> +		DRM_DEBUG_KMS("Failed to read DPCD Display Control registers\n");
> +		return false;
> +	}
> +	DRM_DEBUG_KMS("EDP DPCD : %*ph\n", (int) sizeof(dpcd_edp), dpcd_edp);
> +
> +	if (dpcd_edp[0] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAPABLE &&
> +			(dpcd_edp[0] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAPABLE) &&
> +			(dpcd_edp[1] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAPABLE) &&
> +			((read_mode_set_reg(intel_dp) &
> +					DP_EDP_BACKLIGHT_BRIGHTNESS_CTL_MODE_DPCD_MASK))) {
> +
> +		DRM_DEBUG_KMS("AUX Backlight Control Supported!\n");
> +
> +		if (dpcd_edp[1] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
> +			intel_dp->aux_backlight.use_lsb_reg = true;
> +
> +		return true;
> +	}
> +	return false;
> +}
> +
> +#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
> +
> +/**
> + * Sends the current backlight level over the aux channel, checking if its using
> + * 8-bit or 16 bit value (MSB and LSB)
> + */
> +static void
> +write_aux_backlight_level(struct intel_dp *intel_dp, uint16_t level)
> +{
> +	uint8_t vals[2] = { 0x0 };
> +
> +	vals[0] = level;
> +	DRM_DEBUG_KMS("Level 0x%x\n", level);
> +
> +	/* Write the MSB and/or LSB */
> +	 if (intel_dp->aux_backlight.use_lsb_reg) {
> +		vals[0] = (level & 0xFF00) >> 8;
> +		vals[1] = (level & 0xFF);
> +		if (drm_dp_dpcd_writeb(&intel_dp->aux,
> +				DP_EDP_BACKLIGHT_BRIGHTNESS_MSB, vals[1]) < 0) {
> +			DRM_DEBUG_KMS("Failed to write aux backlight level\n");
> +			return;
> +		}
> +	 }
> +	if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
> +			vals[0]) < 0) {
> +		DRM_DEBUG_KMS("Failed to write aux backlight level\n");
> +		return;
> +	}
> +	intel_dp->aux_backlight.level = level;
> +}
> +
> +static void set_aux_backlight_enable(struct intel_dp *intel_dp, bool enable)
> +{
> +	uint8_t reg_val = 0;
> +
> +	if (intel_dp_dpcd_read_wake(&intel_dp->aux,
> +				DP_EDP_DISPLAY_CONTROL_REGISTER,
> +				&reg_val, sizeof(reg_val)) < 0) {
> +		DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
> +				DP_EDP_DISPLAY_CONTROL_REGISTER);
> +		return;
> +	}
> +	if (enable)
> +		reg_val |= DP_EDP_BACKLIGHT_ENABLE;
> +	else
> +		reg_val &= ~(DP_EDP_BACKLIGHT_ENABLE);
> +
> +	if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
> +			reg_val) < 0) {
> +		DRM_DEBUG_KMS("Failed to %s aux backlight\n",
> +				enable ? "enable" : "disable");
> +		return;
> +	}
> +	intel_dp->aux_backlight.enabled = enable;
> +}
> +
> +/**
> + * intel_dp_aux_backlight_device_update_status
> + * Writes to the sysfs backlight interface will come here to set the
> + * backlight level or disable/enable the backlight
> + */
> +static int
> +intel_dp_aux_backlight_device_update_status(struct backlight_device *bd)
> +{
> +	struct intel_connector *intel_connector = bl_get_data(bd);
> +	struct drm_connector *connector = &intel_connector->base;
> +	struct intel_encoder *intel_encoder = intel_attached_encoder(connector);
> +	struct intel_dp *intel_dp = enc_to_intel_dp(&intel_encoder->base);
> +	struct drm_device *dev = connector->dev;
> +	uint32_t hw_level;
> +	bool bl_enable = false;
> +
> +	DRM_DEBUG_KMS("Updating intel_aux_backlight-DP, brightness=%d/%d, bl_power %d\n",
> +			bd->props.brightness, bd->props.max_brightness,
> +			bd->props.power);
> +
> +	if (connector->status != connector_status_connected)
> +		return -ENODEV;
> +
> +	WARN_ON(intel_dp->aux_backlight.max == 0);
> +
> +	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
> +
> +	hw_level = scale(bd->props.brightness,
> +			0, bd->props.max_brightness,
> +			intel_dp->aux_backlight.min, intel_dp->aux_backlight.max);
> +
> +	if (intel_dp->aux_backlight.level != hw_level)
> +		write_aux_backlight_level(intel_dp, hw_level);
> +
> +	/*
> +	 * This gets called when bl_power is written to as well. Check if the
> +	 * bl_power state has changed and write it
> +	 */
> +	bl_enable = (bd->props.power == FB_BLANK_UNBLANK);
> +	if (intel_dp->aux_backlight.enabled != bl_enable)
> +		set_aux_backlight_enable(intel_dp, bl_enable);
> +
> +	drm_modeset_unlock(&dev->mode_config.connection_mutex);
> +	return 0;
> +}
> +
> +/**
> + * intel_dp_aux_backlight_device_get_brightness
> + * Called on read of the sysfs backlight interface to get the current backlight
> + * value from the AUX channel.
> + */
> +static int
> +intel_dp_aux_backlight_device_get_brightness(struct backlight_device *bd)
> +{
> +	struct intel_connector *intel_connector = bl_get_data(bd);
> +	struct drm_connector *connector = &intel_connector->base;
> +	struct drm_device *dev = connector->dev;
> +	struct intel_encoder *intel_encoder = intel_attached_encoder(connector);
> +	struct intel_dp *intel_dp = enc_to_intel_dp(&intel_encoder->base);
> +	int ret;
> +
> +	if (connector->status != connector_status_connected)
> +		return -ENODEV;
> +
> +	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
> +
> +	intel_dp->aux_backlight.level = read_aux_backlight_level(intel_dp);
> +
> +	ret = scale(intel_dp->aux_backlight.level,
> +			intel_dp->aux_backlight.min, intel_dp->aux_backlight.max,
> +			0, bd->props.max_brightness);
> +
> +	drm_modeset_unlock(&dev->mode_config.connection_mutex);
> +
> +	return ret;
> +}
> +
> +const struct backlight_ops intel_dp_backlight_device_ops = {
> +	.update_status = intel_dp_aux_backlight_device_update_status,
> +	.get_brightness = intel_dp_aux_backlight_device_get_brightness,
> +};
> +
> +static void setup_backlight_ops(struct intel_backlight *backlight)
> +{
> +	backlight->bl_ops = &intel_dp_backlight_device_ops;
> +}
> +#else
> +
> +static void setup_backlight_ops(struct intel_backlight *backlight)
> +{
> +
> +}
> +#endif /* CONFIG_BACKLIGHT_CLASS_DEVICE */
> +
> +
> +static void _aux_backlight_init(struct intel_dp *intel_dp)
> +{
> +	struct drm_connector *connector = &intel_dp->attached_connector->base;
> +
> +	intel_dp->aux_backlight.max = MAX_AUX_BL_HW_LEVEL;
> +	intel_dp->aux_backlight.min = MIN_AUX_BL_HW_LEVEL;
> +
> +	intel_dp->aux_backlight.level = read_aux_backlight_level(intel_dp);
> +	intel_dp->aux_backlight.enabled = get_aux_backlight_enable(&intel_dp->aux);
> +
> +	setup_backlight_ops(&intel_dp->aux_backlight);
> +	/*
> +	* For AUX backlight, using different name for each DP/eDP connector
> +	* will produce registration of multiple DP-AUX backlight devices in
> +	* the driver.
> +	*/
> +	snprintf(intel_dp->aux_backlight.bl_name, INTEL_BACKLIGHT_NAME_LEN,
> +			"intel_aux_backlight-%s", connector->name);
> +}
> +
> +/**
> + * Called on connector initialization to check for aux backlight control
> + * capability and if present, initialize it.
> + */
> +
> +void intel_dp_aux_backlight_init(struct intel_dp *intel_dp,
> +		struct drm_connector *connector)
> +{
> +	if (!is_aux_display_control_capable(connector)) {
> +		DRM_DEBUG_KMS("Backlight control over AUX not supported\n");
> +		return;
> +	}
> +	intel_dp->aux_backlight.present = true;
> +
> +	_aux_backlight_init(intel_dp);
> +
> +	DRM_DEBUG_KMS("Connector %s backlight %s, brightness %u/%u\n",
> +			connector->name,
> +			intel_dp->aux_backlight.enabled ? "enabled" : "disabled",
> +			intel_dp->aux_backlight.level, intel_dp->aux_backlight.max);
> +}
> +/**
> + * Cleanup aux backlight control data
> + */
> +void intel_dp_aux_backlight_destroy(struct drm_connector *connector)
> +{
> +	struct intel_encoder *intel_encoder = intel_attached_encoder(connector);
> +	struct intel_dp *intel_dp = enc_to_intel_dp(&intel_encoder->base);
> +
> +	intel_dp->aux_backlight.present = false;
> +}
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 46484e4..438a87b 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -163,26 +163,31 @@ struct intel_encoder {
>  	enum hpd_pin hpd_pin;
>  };
>  
> +#define INTEL_BACKLIGHT_NAME_LEN 50
> +struct intel_backlight {
> +	bool present;
> +	u32 level;
> +	u32 min;
> +	u32 max;
> +	bool enabled;
> +	bool combination_mode;	/* gen 2/4 only */
> +	bool active_low_pwm;
> +
> +	/* PWM chip */
> +	struct pwm_device *pwm;
> +
> +	struct backlight_device *device;
> +	const struct backlight_ops *bl_ops;
> +	char bl_name[INTEL_BACKLIGHT_NAME_LEN];
> +	bool use_lsb_reg;	/* aux backlight only */
> +};
> +
>  struct intel_panel {
>  	struct drm_display_mode *fixed_mode;
>  	struct drm_display_mode *downclock_mode;
>  	int fitting_mode;
>  
> -	/* backlight */
> -	struct {
> -		bool present;
> -		u32 level;
> -		u32 min;
> -		u32 max;
> -		bool enabled;
> -		bool combination_mode;	/* gen 2/4 only */
> -		bool active_low_pwm;
> -
> -		/* PWM chip */
> -		struct pwm_device *pwm;
> -
> -		struct backlight_device *device;
> -	} backlight;
> +	struct intel_backlight backlight;
>  
>  	void (*backlight_power)(struct intel_connector *, bool enable);
>  };
> @@ -771,6 +776,8 @@ struct intel_dp {
>  	unsigned long compliance_test_type;
>  	unsigned long compliance_test_data;
>  	bool compliance_test_active;
> +
> +	struct intel_backlight aux_backlight;
>  };
>  
>  struct intel_digital_port {
> @@ -1210,6 +1217,11 @@ void intel_edp_drrs_invalidate(struct drm_device *dev,
>  		unsigned frontbuffer_bits);
>  void intel_edp_drrs_flush(struct drm_device *dev, unsigned frontbuffer_bits);
>  void hsw_dp_set_ddi_pll_sel(struct intel_crtc_state *pipe_config);
> +bool intel_dp_get_dpcd(struct intel_dp *intel_dp);
> +ssize_t intel_dp_dpcd_read_wake(struct drm_dp_aux *aux, unsigned int offset,
> +		void *buffer, size_t size);
> +uint32_t scale(uint32_t source_val, uint32_t source_min, uint32_t source_max,
> +		uint32_t target_min, uint32_t target_max);
>  
>  /* intel_dp_mst.c */
>  int intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int conn_id);
> @@ -1328,6 +1340,10 @@ extern struct drm_display_mode *intel_find_panel_downclock(
>  void intel_backlight_register(struct drm_device *dev);
>  void intel_backlight_unregister(struct drm_device *dev);
>  
> +/* intel_dp_aux_backlight_ctl.c */
> +void intel_dp_aux_backlight_init(struct intel_dp *intel_dp,
> +			struct drm_connector *connector);
> +void intel_dp_aux_backlight_destroy(struct drm_connector *connector);
>  
>  /* intel_psr.c */
>  void intel_psr_enable(struct intel_dp *intel_dp);
> diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
> index 2034438a..c61fb92 100644
> --- a/drivers/gpu/drm/i915/intel_panel.c
> +++ b/drivers/gpu/drm/i915/intel_panel.c
> @@ -410,7 +410,7 @@ intel_panel_detect(struct drm_device *dev)
>   * Return @source_val in range [@source_min..@source_max] scaled to range
>   * [@target_min..@target_max].
>   */
> -static uint32_t scale(uint32_t source_val,
> +uint32_t scale(uint32_t source_val,
>  		      uint32_t source_min, uint32_t source_max,
>  		      uint32_t target_min, uint32_t target_max)
>  {
> @@ -1151,18 +1151,23 @@ static const struct backlight_ops intel_backlight_device_ops = {
>  	.get_brightness = intel_backlight_device_get_brightness,
>  };
>  
> -static int intel_backlight_device_register(struct intel_connector *connector)
> +static void setup_backlight_ops(struct intel_backlight *backlight)
> +{
> +	backlight->bl_ops = &intel_backlight_device_ops;
> +}
> +
> +static int intel_backlight_device_register(struct intel_connector *connector,
> +		struct intel_backlight *backlight)
>  {
> -	struct intel_panel *panel = &connector->panel;
>  	struct backlight_properties props;
>  
> -	if (WARN_ON(panel->backlight.device))
> +	if (WARN_ON(backlight->device))
>  		return -ENODEV;
>  
> -	if (!panel->backlight.present)
> +	if (!backlight->present)
>  		return 0;
>  
> -	WARN_ON(panel->backlight.max == 0);
> +	WARN_ON(backlight->max == 0);
>  
>  	memset(&props, 0, sizeof(props));
>  	props.type = BACKLIGHT_RAW;
> @@ -1171,30 +1176,25 @@ static int intel_backlight_device_register(struct intel_connector *connector)
>  	 * Note: Everything should work even if the backlight device max
>  	 * presented to the userspace is arbitrarily chosen.
>  	 */
> -	props.max_brightness = panel->backlight.max;
> -	props.brightness = scale_hw_to_user(connector,
> -					    panel->backlight.level,
> -					    props.max_brightness);
> +	props.max_brightness = backlight->max;
> +	props.brightness = scale(backlight->level, backlight->min, backlight->max,
> +		     0, props.max_brightness);
>  
> -	if (panel->backlight.enabled)
> +	if (backlight->enabled)
>  		props.power = FB_BLANK_UNBLANK;
>  	else
>  		props.power = FB_BLANK_POWERDOWN;
>  
> -	/*
> -	 * Note: using the same name independent of the connector prevents
> -	 * registration of multiple backlight devices in the driver.
> -	 */
> -	panel->backlight.device =
> -		backlight_device_register("intel_backlight",
> +	backlight->device =
> +		backlight_device_register(backlight->bl_name,
>  					  connector->base.kdev,
>  					  connector,
> -					  &intel_backlight_device_ops, &props);
> +					  backlight->bl_ops, &props);
>  
> -	if (IS_ERR(panel->backlight.device)) {
> +	if (IS_ERR(backlight->device)) {
>  		DRM_ERROR("Failed to register backlight: %ld\n",
> -			  PTR_ERR(panel->backlight.device));
> -		panel->backlight.device = NULL;
> +			  PTR_ERR(backlight->device));
> +		backlight->device = NULL;
>  		return -ENODEV;
>  	}
>  
> @@ -1204,21 +1204,25 @@ static int intel_backlight_device_register(struct intel_connector *connector)
>  	return 0;
>  }
>  
> -static void intel_backlight_device_unregister(struct intel_connector *connector)
> +static void intel_backlight_device_unregister(struct intel_backlight *backlight)
>  {
> -	struct intel_panel *panel = &connector->panel;
> -
> -	if (panel->backlight.device) {
> -		backlight_device_unregister(panel->backlight.device);
> -		panel->backlight.device = NULL;
> +	if (backlight->device) {
> +		backlight_device_unregister(backlight->device);
> +		backlight->device = NULL;
>  	}
>  }
> +
>  #else /* CONFIG_BACKLIGHT_CLASS_DEVICE */
> -static int intel_backlight_device_register(struct intel_connector *connector)
> +
> +static int intel_backlight_device_register(struct intel_connector *connector,
> +		struct intel_backlight *backlight)
>  {
>  	return 0;
>  }
> -static void intel_backlight_device_unregister(struct intel_connector *connector)
> +static void intel_backlight_device_unregister(struct intel_backlight *backlight)
> +{
> +}
> +static void setup_backlight_ops(struct intel_backlight *backlight)
>  {
>  }
>  #endif /* CONFIG_BACKLIGHT_CLASS_DEVICE */
> @@ -1652,6 +1656,17 @@ int intel_panel_setup_backlight(struct drm_connector *connector, enum pipe pipe)
>  
>  	panel->backlight.present = true;
>  
> +	setup_backlight_ops(&panel->backlight);
> +
> +	/*
> +	 * Note: For internal displays, using the same name independent of the
> +	 * connector prevents registration of multiple backlight devices in the
> +	 * driver.
> +	 */
> +	strncpy(panel->backlight.bl_name, "intel_backlight",
> +			INTEL_BACKLIGHT_NAME_LEN);
> +	panel->backlight.bl_name[INTEL_BACKLIGHT_NAME_LEN - 1] = '\0';
> +
>  	DRM_DEBUG_KMS("Connector %s backlight initialized, %s, brightness %u/%u\n",
>  		      connector->name,
>  		      panel->backlight.enabled ? "enabled" : "disabled",
> @@ -1757,16 +1772,42 @@ void intel_panel_fini(struct intel_panel *panel)
>  
>  void intel_backlight_register(struct drm_device *dev)
>  {
> -	struct intel_connector *connector;
> +	struct intel_connector *intel_connector;
> +
> +	list_for_each_entry(intel_connector, &dev->mode_config.connector_list,
> +			base.head) {
> +		struct drm_connector *connector = &intel_connector->base;
> +
> +		intel_backlight_device_register(intel_connector,
> +				&intel_connector->panel.backlight);
> +
> +		if (connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
> +				connector->connector_type == DRM_MODE_CONNECTOR_eDP) {
> +			struct intel_encoder *encoder = intel_attached_encoder(connector);
> +			struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
>  
> -	list_for_each_entry(connector, &dev->mode_config.connector_list, base.head)
> -		intel_backlight_device_register(connector);
> +			intel_backlight_device_register(intel_connector,
> +					&intel_dp->aux_backlight);
> +		}
> +	}
>  }
>  
>  void intel_backlight_unregister(struct drm_device *dev)
>  {
> -	struct intel_connector *connector;
> +	struct intel_connector *intel_connector;
> +
> +	list_for_each_entry(intel_connector, &dev->mode_config.connector_list,
> +			base.head) {
> +		struct drm_connector *connector = &intel_connector->base;
> +
> +		intel_backlight_device_unregister(&intel_connector->panel.backlight);
>  
> -	list_for_each_entry(connector, &dev->mode_config.connector_list, base.head)
> -		intel_backlight_device_unregister(connector);
> +		if (connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
> +				connector->connector_type == DRM_MODE_CONNECTOR_eDP) {
> +			struct intel_encoder *encoder = intel_attached_encoder(connector);
> +			struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
> +
> +			intel_backlight_device_unregister(&intel_dp->aux_backlight);
> +		}
> +	}
>  }
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 8c52d0ef1..5826183 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -455,16 +455,22 @@
>  # define DP_EDP_14			    0x03
>  
>  #define DP_EDP_GENERAL_CAP_1		    0x701
> +#define DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAPABLE      (1 << 0)
> +#define DP_EDP_BACKLIGHT_AUX_ENABLE_CAPABLE           (1 << 2)
>  
>  #define DP_EDP_BACKLIGHT_ADJUSTMENT_CAP     0x702
> +#define DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAPABLE   (1 << 1)
> +#define DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT        (1 << 2)
>  
>  #define DP_EDP_GENERAL_CAP_2		    0x703
>  
>  #define DP_EDP_GENERAL_CAP_3		    0x704    /* eDP 1.4 */
>  
>  #define DP_EDP_DISPLAY_CONTROL_REGISTER     0x720
> +#define DP_EDP_BACKLIGHT_ENABLE                       (1 << 0)
>  
>  #define DP_EDP_BACKLIGHT_MODE_SET_REGISTER  0x721
> +#define DP_EDP_BACKLIGHT_BRIGHTNESS_CTL_MODE_DPCD_MASK 0x2
>  
>  #define DP_EDP_BACKLIGHT_BRIGHTNESS_MSB     0x722
>  #define DP_EDP_BACKLIGHT_BRIGHTNESS_LSB     0x723
> -- 
> 1.9.3
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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