[Intel-gfx] [RFC CABC PATCH v2 3/3] drm/i915: CABC support for backlight control

Singh, Gaurav K gaurav.k.singh at intel.com
Thu Jul 30 03:48:23 PDT 2015



On 7/24/2015 5:54 PM, Deepak M wrote:
> In CABC (Content Adaptive Brightness Control) content grey level
> scale can be increased while simultaneously decreasing
> brightness of the backlight to achieve same perceived brightness.
>
> The CABC is not standardized and panel vendors are free to follow
> their implementation. The CABC implementaion here assumes that the
> panels use standard SW register for control.
>
> In this design there will be no PWM signal from the SoC and DCS
> commands are sent to enable and control the backlight brightness.
>
> v2:
> - Created a new backlight driver for cabc, which will be registered
>    only when it cabc is supported by panel.
>    (Addressed comment from Daniel Vetter)
>
> Signed-off-by: Deepak M <m.deepak at intel.com>
> ---
>   drivers/gpu/drm/i915/Makefile         |    1 +
>   drivers/gpu/drm/i915/intel_drv.h      |    3 +-
>   drivers/gpu/drm/i915/intel_dsi.c      |   13 ++
>   drivers/gpu/drm/i915/intel_dsi_cabc.c |  349 +++++++++++++++++++++++++++++++++
>   drivers/gpu/drm/i915/intel_dsi_cabc.h |   45 +++++
>   drivers/gpu/drm/i915/intel_panel.c    |   22 ++-
>   include/video/mipi_display.h          |    8 +
>   7 files changed, 436 insertions(+), 5 deletions(-)
>   create mode 100644 drivers/gpu/drm/i915/intel_dsi_cabc.c
>   create mode 100644 drivers/gpu/drm/i915/intel_dsi_cabc.h
>
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index de21965..a73953c 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -75,6 +75,7 @@ i915-y += dvo_ch7017.o \
>   	  intel_dp_mst.o \
>   	  intel_dsi.o \
>   	  intel_dsi_pll.o \
> +	  intel_dsi_cabc.o \
>   	  intel_dsi_panel_vbt.o \
>   	  intel_dvo.o \
>   	  intel_hdmi.o \
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 3f0a890..9f806dd5 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1319,7 +1319,8 @@ extern struct drm_display_mode *intel_find_panel_downclock(
>   				struct drm_connector *connector);
>   void intel_backlight_register(struct drm_device *dev);
>   void intel_backlight_unregister(struct drm_device *dev);
> -
> +extern int cabc_backlight_device_register(struct intel_connector *connector);
> +extern void cabc_backlight_device_unregister(struct intel_connector *connector);
>   
>   /* intel_psr.c */
>   void intel_psr_enable(struct intel_dp *intel_dp);
> diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
> index 98998e9..8f006f2 100644
> --- a/drivers/gpu/drm/i915/intel_dsi.c
> +++ b/drivers/gpu/drm/i915/intel_dsi.c
> @@ -34,6 +34,7 @@
>   #include "i915_drv.h"
>   #include "intel_drv.h"
>   #include "intel_dsi.h"
> +#include "intel_dsi_cabc.h"
>   
>   static const struct {
>   	u16 panel_id;
> @@ -376,6 +377,7 @@ static void intel_dsi_enable(struct intel_encoder *encoder)
>   	struct drm_device *dev = encoder->base.dev;
>   	struct drm_i915_private *dev_priv = dev->dev_private;
>   	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
> +	struct intel_connector *connector = intel_dsi->attached_connector;
>   	enum port port;
>   
>   	DRM_DEBUG_KMS("\n");
> @@ -396,6 +398,9 @@ static void intel_dsi_enable(struct intel_encoder *encoder)
>   
>   		intel_dsi_port_enable(encoder);
>   	}
> +
> +	if (dev_priv->vbt.dsi.config->cabc_supported)
> +		cabc_enable_backlight(connector);
>   }
>   
>   static void intel_dsi_pre_enable(struct intel_encoder *encoder)
> @@ -469,11 +474,15 @@ static void intel_dsi_disable(struct intel_encoder *encoder)
>   	struct drm_device *dev = encoder->base.dev;
>   	struct drm_i915_private *dev_priv = dev->dev_private;
>   	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
> +	struct intel_connector *connector = intel_dsi->attached_connector;
>   	enum port port;
>   	u32 temp;
>   
>   	DRM_DEBUG_KMS("\n");
>   
> +	if (dev_priv->vbt.dsi.config->cabc_supported)
> +		cabc_disable_backlight(connector);
> +
>   	if (is_vid_mode(intel_dsi)) {
>   		for_each_dsi_port(port, intel_dsi->ports)
>   			wait_for_dsi_fifo_empty(intel_dsi, port);
> @@ -1099,6 +1108,10 @@ void intel_dsi_init(struct drm_device *dev)
>   
>   	intel_panel_init(&intel_connector->panel, fixed_mode, NULL);
>   
> +	if (dev_priv->vbt.dsi.config->cabc_supported)
> +		cabc_setup_backlight(connector,
> +			intel_encoder->crtc_mask ==
> +				(1 << PIPE_A) ? PIPE_A : PIPE_B);
>   	return;
>   
>   err:
> diff --git a/drivers/gpu/drm/i915/intel_dsi_cabc.c b/drivers/gpu/drm/i915/intel_dsi_cabc.c
> new file mode 100644
> index 0000000..2a78326
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/intel_dsi_cabc.c
> @@ -0,0 +1,349 @@
> +/*
> + * Copyright © 2006-2010 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 <linux/kernel.h>
> +#include <linux/moduleparam.h>
> +#include "intel_drv.h"
> +#include "intel_dsi.h"
> +#include "i915_drv.h"
> +#include "intel_dsi_cabc.h"
> +#include <video/mipi_display.h>
> +#include <drm/drm_mipi_dsi.h>
> +
> +int cabc_setup_backlight(struct intel_connector *connector,
> +		enum pipe unused)
> +{
> +	struct drm_device *dev = connector->base.dev;
> +	struct intel_dsi *intel_dsi = NULL;
> +	struct drm_crtc *crtc = NULL;
> +	struct intel_encoder *encoder = NULL;
> +	struct intel_panel *panel = &connector->panel;
> +	struct mipi_dsi_device *dsi_device;
> +	u8 level;
> +
> +	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
> +		for_each_encoder_on_crtc(dev, crtc, encoder) {
> +			if (encoder->type == INTEL_OUTPUT_DSI)
> +				intel_dsi = enc_to_intel_dsi(&encoder->base);
> +		}
> +	}
> +	dsi_device = intel_dsi->dsi_hosts[0]->device;
This will work only for MIPI Port A not for MIPI Port C. Use 
for_each_dsi_port macro and intel_dsi->dsi_hosts[port] to correctly 
reach to mipi_dsi_device for both ports. If it is dual link, break after 
the completion of the first iteration.
> +	panel->backlight.max = CABC_MAX_VALUE;
> +	panel->backlight.level = CABC_MAX_VALUE;
> +	level = CABC_MAX_VALUE;
> +	panel->backlight.enabled = true;
> +	return 0;
> +}
> +
> +u32 cabc_get_backlight(struct intel_connector *connector)
> +{
> +	struct drm_device *dev = connector->base.dev;
> +	struct intel_dsi *intel_dsi = NULL;
> +	struct drm_crtc *crtc = NULL;
> +	struct intel_encoder *encoder = NULL;
> +	struct mipi_dsi_device *dsi_device;
> +	struct intel_panel *panel = &connector->panel;
> +	u8 data[2] = {0};
> +	enum port port = PORT_A;
will fail for single link MIPI Port C.
> +	u32 ret;
> +
> +	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
> +		for_each_encoder_on_crtc(dev, crtc, encoder) {
> +			if (encoder->type == INTEL_OUTPUT_DSI)
> +				intel_dsi = enc_to_intel_dsi(&encoder->base);
> +		}
> +	}
> +	if (intel_dsi->dual_link) {
Put the below or required logic into static inline function returning 
enum port .
> +		if (intel_dsi->dl_cabc_port == CABC_PORT_A ||
> +				intel_dsi->dl_cabc_port == CABC_PORT_A_AND_C)
> +			port = PORT_A;
> +		else if (intel_dsi->dl_cabc_port == CABC_PORT_C)
> +			port = PORT_C;
> +	}
Use for_each_dsi_port macro here . call the  inline function within 
for_each_dsi_port macro to get the required enum port for dual link.
> +
> +	dsi_device = intel_dsi->dsi_hosts[port]->device;
> +	mipi_dsi_dcs_read(dsi_device, MIPI_DCS_CABC_LEVEL_RD, data, 2);
> +
> +	ret = (data[1] * panel->backlight.max) / 255;
> +	return ret;
> +}
> +
> +void cabc_set_backlight(struct intel_connector *connector, u32 level)
> +{
> +	struct drm_device *dev = connector->base.dev;
> +	struct intel_dsi *intel_dsi = NULL;
> +	struct drm_crtc *crtc = NULL;
> +	struct intel_encoder *encoder = NULL;
> +	struct mipi_dsi_device *dsi_device;
> +	u8 data[2] = {0};
> +	enum port port = PORT_A;
> +	struct intel_panel *panel = &connector->panel;
> +	u8 count = 1;
> +	u32 hw_level;
> +
> +	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
> +		for_each_encoder_on_crtc(dev, crtc, encoder) {
> +			if (encoder->type == INTEL_OUTPUT_DSI)
> +				intel_dsi = enc_to_intel_dsi(&encoder->base);
> +		}
> +	}
> +
> +	if (intel_dsi->dual_link) {
Put the below logic into static inline function returning enum port .
> +		if (intel_dsi->dl_cabc_port == CABC_PORT_A)
> +			port = PORT_A;
> +		else if (intel_dsi->dl_cabc_port == CABC_PORT_C)
> +			port = PORT_C;
> +		else if (intel_dsi->dl_cabc_port == CABC_PORT_A_AND_C)
> +			port = PORT_A;
> +	}
> +
Below part not required. use for_each_dsi_port macro.
> +	if (intel_dsi->dual_link && intel_dsi->dl_cabc_port ==
> +			CABC_PORT_A_AND_C)
> +		count = 2;
> +
> +
> +	hw_level = level % (panel->backlight.max + 1);
> +	hw_level = (hw_level * 255) / panel->backlight.max;
> +	panel->backlight.level = hw_level;
> +
Use for_each_dsi_port macro as explained above.
> +	do {
> +		dsi_device = intel_dsi->dsi_hosts[port]->device;
> +		data[1] = hw_level;
> +		data[0] = MIPI_DCS_CABC_LEVEL_WR;
> +		mipi_dsi_dcs_write_buffer(dsi_device, data, 2);
> +		if (count == 2)
> +			port = PORT_C;
> +	} while (--count > 0);
> +}
> +
> +void cabc_enable_backlight(struct intel_connector *connector)
> +{
> +	struct drm_device *dev = connector->base.dev;
> +	struct intel_dsi *intel_dsi = NULL;
> +	struct drm_crtc *crtc = NULL;
> +	struct intel_encoder *encoder = NULL;
> +	struct intel_panel *panel = &connector->panel;
> +	struct mipi_dsi_device *dsi_device;
> +	enum port port = PORT_A;
Will fail for single link Port C
> +	u8 data[2] = {0};
> +	u8 count = 1;
> +
> +	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
> +		for_each_encoder_on_crtc(dev, crtc, encoder) {
> +			if (encoder->type == INTEL_OUTPUT_DSI)
> +				intel_dsi = enc_to_intel_dsi(&encoder->base);
> +		}
> +	}
> +
> +	if (intel_dsi->dual_link) {
Same comment .Put the below logic into static inline function returning 
enum port .
> +		if (intel_dsi->dl_cabc_port == CABC_PORT_A)
> +			port = PORT_A;
> +		else if (intel_dsi->dl_cabc_port == CABC_PORT_C)
> +			port = PORT_C;
Also below condition need not be taken into the inline function. Since 
it is dual link and with other conditions are met, then 
CABC_PORT_A_AND_C will be automatically taken care for both ports by the 
for_each_dsi_port macro.
Within for_each_dsi_port, just check for intel_dsi->dl_cabc_port != 
CABC_PORT_A_AND_C, if yes call the inline function to get the port no 
and if no, all other conditions will be taken care for both ports by 
for_each_dsi_port.
Before the end of for_each_dsi_port ,you may require to check the 
intel_dsi->dl_cabc_port != CABC_PORT_A_AND_C , so that you can return 
from the macro.
> +		else if (intel_dsi->dl_cabc_port == CABC_PORT_A_AND_C)
> +			port = PORT_A;
> +	}
> +
> +	if (intel_dsi->dual_link && intel_dsi->dl_cabc_port ==
> +			CABC_PORT_A_AND_C)
> +		count = 2;
> +
> +	do {
same comment as above. Use for_each_dsi_port
> +		dsi_device = intel_dsi->dsi_hosts[port]->device;
> +
> +
> +		data[0] = MIPI_DCS_CABC_CONTROL_BRIGHT_WR;
> +		data[1] = CABC_BACKLIGHT | CABC_DIMMING_DISPLAY | CABC_BCTRL;
> +		mipi_dsi_dcs_write_buffer(dsi_device, data, 2);
> +		data[0] = MIPI_DCS_CABC_CONTROL_WR;
> +		data[1] = CABC_VIDEO_MODE;
> +		mipi_dsi_dcs_write_buffer(dsi_device, data, 2);
> +
> +		if (count == 2)
> +			port = PORT_C;
> +	} while (--count > 0);
> +
> +	cabc_set_backlight(connector, panel->backlight.level);
> +}
> +
> +void cabc_disable_backlight(struct intel_connector *connector)
> +{
> +	struct drm_device *dev = connector->base.dev;
> +	struct intel_dsi *intel_dsi = NULL;
> +	struct drm_crtc *crtc = NULL;
> +	struct intel_encoder *encoder = NULL;
> +	struct mipi_dsi_device *dsi_device;
> +	enum port port = PORT_A;
Will fail for single link Port C
> +	u8 data[2] = {0};
> +	u8 count = 1;
> +
> +	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
> +		for_each_encoder_on_crtc(dev, crtc, encoder) {
> +			if (encoder->type == INTEL_OUTPUT_DSI)
> +				intel_dsi = enc_to_intel_dsi(&encoder->base);
> +		}
> +	}
> +
> +	if (intel_dsi->dual_link) {
Same comment as above. Use static inline function for this.
> +		if (intel_dsi->dl_cabc_port == CABC_PORT_A)
> +			port = PORT_A;
> +		else if (intel_dsi->dl_cabc_port == CABC_PORT_C)
> +			port = PORT_C;
> +		else if (intel_dsi->dl_cabc_port == CABC_PORT_A_AND_C)
> +			port = PORT_A;
> +	}
> +
> +	if (intel_dsi->dual_link && intel_dsi->dl_cabc_port ==
> +			CABC_PORT_A_AND_C)
> +		count = 2;
> +
> +	do {
Use for_each_dsi_port macro
> +		dsi_device = intel_dsi->dsi_hosts[port]->device;
> +
> +		cabc_set_backlight(connector, 0);
> +		data[1] = CABC_OFF;
> +		data[0] = MIPI_DCS_CABC_CONTROL_WR;
> +		mipi_dsi_dcs_write_buffer(dsi_device, data, 2);
> +		data[0] = MIPI_DCS_CABC_CONTROL_BRIGHT_WR;
> +		mipi_dsi_dcs_write_buffer(dsi_device, data, 2);
> +
> +		if (count == 2)
> +			port = PORT_C;
> +	} while (--count > 0);
> +}
> +
> +static int cabc_backlight_device_update_status(struct backlight_device *bd)
> +{
> +	struct intel_connector *connector = bl_get_data(bd);
> +	struct intel_panel *panel = &connector->panel;
> +	struct drm_device *dev = connector->base.dev;
> +
> +	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
> +	DRM_DEBUG_KMS("updating intel_backlight, brightness=%d/%d\n",
> +			bd->props.brightness, bd->props.max_brightness);
> +	cabc_set_backlight(connector, bd->props.brightness);
> +
> +	/*
> +	 * Allow flipping bl_power as a sub-state of enabled. Sadly the
> +	 * backlight class device does not make it easy to to differentiate
> +	 * between callbacks for brightness and bl_power, so our backlight_power
> +	 * callback needs to take this into account.
> +	 */
> +	if (panel->backlight.enabled) {
> +		if (panel->backlight_power) {
> +			bool enable = bd->props.power == FB_BLANK_UNBLANK &&
> +				bd->props.brightness != 0;
> +			panel->backlight_power(connector, enable);
> +		}
> +	} else {
> +		bd->props.power = FB_BLANK_POWERDOWN;
> +	}
> +
> +	drm_modeset_unlock(&dev->mode_config.connection_mutex);
> +	return 0;
> +}
> +
> +static int cabc_backlight_device_get_brightness(struct backlight_device *bd)
> +{
> +	struct intel_connector *connector = bl_get_data(bd);
> +	struct drm_device *dev = connector->base.dev;
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	int ret;
> +
> +	intel_runtime_pm_get(dev_priv);
> +	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
> +
> +	ret = cabc_get_backlight(connector);
> +
> +	drm_modeset_unlock(&dev->mode_config.connection_mutex);
> +	intel_runtime_pm_put(dev_priv);
> +
> +	return ret;
> +}
> +
> +static const struct backlight_ops cabc_backlight_device_ops = {
> +	.update_status = cabc_backlight_device_update_status,
> +	.get_brightness = cabc_backlight_device_get_brightness,
> +};
> +
> +int cabc_backlight_device_register(struct intel_connector *connector)
> +{
> +	struct intel_panel *panel = &connector->panel;
> +	struct backlight_properties props;
> +
> +	if (WARN_ON(panel->backlight.device))
> +		return -ENODEV;
> +
> +	if (!panel->backlight.present)
> +		return 0;
> +
> +	WARN_ON(panel->backlight.max == 0);
> +
> +	memset(&props, 0, sizeof(props));
> +	props.type = BACKLIGHT_FIRMWARE;
> +
> +	/*
> +	 * 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 = props.max_brightness;
> +
> +	if (panel->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",
> +				connector->base.kdev,
> +				connector,
> +				&cabc_backlight_device_ops, &props);
> +
> +	if (IS_ERR(panel->backlight.device)) {
> +		DRM_ERROR("Failed to register backlight: %ld\n",
> +				PTR_ERR(panel->backlight.device));
> +		panel->backlight.device = NULL;
> +		return -ENODEV;
> +	}
> +
> +	DRM_DEBUG_KMS("Connector %s backlight sysfs interface registered\n",
> +			connector->base.name);
> +
> +	return 0;
> +}
> +
> +void cabc_backlight_device_unregister(struct intel_connector *connector)
> +{
> +	struct intel_panel *panel = &connector->panel;
> +
> +	if (panel->backlight.device) {
> +		backlight_device_unregister(panel->backlight.device);
> +		panel->backlight.device = NULL;
> +	}
> +}
> diff --git a/drivers/gpu/drm/i915/intel_dsi_cabc.h b/drivers/gpu/drm/i915/intel_dsi_cabc.h
> new file mode 100644
> index 0000000..5d134f5
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/intel_dsi_cabc.h
> @@ -0,0 +1,45 @@
> +/*
> + * Copyright © 2013 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.
> + *
> + */
> +
> +extern int cabc_backlight_device_register(struct intel_connector *connector);
> +extern void cabc_backlight_device_unregister(struct intel_connector *connector);
> +void cabc_set_backlight(struct intel_connector *connector, u32 level);
> +u32 cabc_get_backlight(struct intel_connector *connector);
> +void cabc_enable_backlight(struct intel_connector *connector);
> +void cabc_disable_backlight(struct intel_connector *connector);
> +int cabc_setup_backlight(struct intel_connector *connector, enum pipe unused);
> +
> +#define CABC_OFF                       (0 << 0)
> +#define CABC_USER_INTERFACE_IMAGE      (1 << 0)
> +#define CABC_STILL_PICTURE             (2 << 0)
> +#define CABC_VIDEO_MODE                        (3 << 0)
> +
> +#define CABC_BACKLIGHT                 (1 << 2)
> +#define CABC_DIMMING_DISPLAY           (1 << 3)
> +#define CABC_BCTRL                     (1 << 5)
> +
> +#define CABC_PORT_A                    0x00
> +#define CABC_PORT_C                    0x01
> +#define CABC_PORT_A_AND_C              0x02
> +#define CABC_MAX_VALUE		       0xff
> diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
> index 55aad23..c73449b 100644
> --- a/drivers/gpu/drm/i915/intel_panel.c
> +++ b/drivers/gpu/drm/i915/intel_panel.c
> @@ -1502,15 +1502,29 @@ void intel_panel_fini(struct intel_panel *panel)
>   void intel_backlight_register(struct drm_device *dev)
>   {
>   	struct intel_connector *connector;
> +	struct drm_i915_private *dev_priv = dev->dev_private;
>   
> -	list_for_each_entry(connector, &dev->mode_config.connector_list, base.head)
> -		intel_backlight_device_register(connector);
> +	list_for_each_entry(connector, &dev->mode_config.connector_list,
> +					base.head) {
> +		if (connector->encoder->type == INTEL_OUTPUT_DSI &&
> +			dev_priv->vbt.dsi.config->cabc_supported)
> +			cabc_backlight_device_register(connector);
> +		else
> +			intel_backlight_device_register(connector);
> +	}
>   }
>   
>   void intel_backlight_unregister(struct drm_device *dev)
>   {
>   	struct intel_connector *connector;
> +	struct drm_i915_private *dev_priv = dev->dev_private;
>   
> -	list_for_each_entry(connector, &dev->mode_config.connector_list, base.head)
> -		intel_backlight_device_unregister(connector);
> +	list_for_each_entry(connector, &dev->mode_config.connector_list,
> +					base.head) {
> +		if (connector->encoder->type == INTEL_OUTPUT_DSI &&
> +			dev_priv->vbt.dsi.config->cabc_supported)
> +			cabc_backlight_device_unregister(connector);
> +		else
> +			intel_backlight_device_unregister(connector);
> +	}
>   }
> diff --git a/include/video/mipi_display.h b/include/video/mipi_display.h
> index ddcc8ca..5b8eeec 100644
> --- a/include/video/mipi_display.h
> +++ b/include/video/mipi_display.h
> @@ -117,6 +117,14 @@ enum {
>   	MIPI_DCS_GET_SCANLINE		= 0x45,
>   	MIPI_DCS_READ_DDB_START		= 0xA1,
>   	MIPI_DCS_READ_DDB_CONTINUE	= 0xA8,
> +	MIPI_DCS_CABC_LEVEL_RD          = 0x52,
> +	MIPI_DCS_CABC_MIN_BRIGHTNESS_RD = 0x5F,
> +	MIPI_DCS_CABC_CONTROL_RD        = 0x56,
> +	MIPI_DCS_CABC_CONTROL_BRIGHT_RD = 0x54,
> +	MIPI_DCS_CABC_LEVEL_WR          = 0x51,
> +	MIPI_DCS_CABC_MIN_BRIGHTNESS_WR = 0x5E,
> +	MIPI_DCS_CABC_CONTROL_WR        = 0x55,
> +	MIPI_DCS_CABC_CONTROL_BRIGHT_WR = 0x53,
>   };
>   
>   /* MIPI DCS pixel formats */



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