[PATCH 0/2] drm/i915: revert DPCD backlight and DBC enabling by default

[PATCH 0/2] drm/i915: revert DPCD backlight and DBC enabling by default

[Jani Nikula]

The two commits being reverted regress machines, a production ThinkPad,
and BXT-P in CI, and there hasn't been adequate response to follow-up or
fix the issues. The regressions were reported 3½ weeks ago. The reverts
are long overdue already. Back to the drawing board.

BR,
Jani.


Cc: Jenny TC <jenny.tc@intel.com>
Cc: David Weinehall <david.weinehall@linux.intel.com>
Cc: Puthikorn Voravootivat <puthik@chromium.org>
Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>


Jani Nikula (2):
  Revert "drm/i915: Add option to support dynamic backlight via DPCD"
  Revert "drm/i915: Add heuristic to determine better way to adjust
    brightness"

 drivers/gpu/drm/i915/i915_params.c            | 12 +---
 drivers/gpu/drm/i915/i915_params.h            |  5 +-
 drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 87 +--------------------------
 3 files changed, 8 insertions(+), 96 deletions(-)

-- 
2.11.0

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[PATCH 1/2] Revert "drm/i915: Add option to support dynamic backlight via DPCD"

[Jani Nikula]

This reverts commit ae25eceab616d16a07bcaa434b84463d58a3bdc3.

The DPCD backlight commits regress a Thinkpad X1 Carbon 4th Gen and a
BXT-P (in CI). Enabling dynamic backlight boots to a black screen, and
enabling DPCD backlight leads to a black screen after suspend/resume.

References: http://mid.mail-archive.com/20170706135349.6tu3lz7uehazlnnn@boom
References: http://mid.mail-archive.com/20170627132326.f2q3yn4bh5flji4q@boom
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101619
Reported-by: David Weinehall <david.weinehall@linux.intel.com>
Fixes: ae25eceab616 ("drm/i915: Add option to support dynamic backlight via DPCD")
Cc: Jenny TC <jenny.tc@intel.com>
Cc: David Weinehall <david.weinehall@linux.intel.com>
Cc: Puthikorn Voravootivat <puthik@chromium.org>
Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: intel-gfx@lists.freedesktop.org
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
 drivers/gpu/drm/i915/i915_params.c            |  5 -----
 drivers/gpu/drm/i915/i915_params.h            |  3 +--
 drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 26 --------------------------
 3 files changed, 1 insertion(+), 33 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 88b9d3e6713a..5b5ab15d191f 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -65,7 +65,6 @@ struct i915_params i915 __read_mostly = {
 	.inject_load_failure = 0,
 	.enable_dpcd_backlight = -1,
 	.enable_gvt = false,
-	.enable_dbc = true,
 };
 
 module_param_named(modeset, i915.modeset, int, 0400);
@@ -255,7 +254,3 @@ MODULE_PARM_DESC(enable_dpcd_backlight,
 module_param_named(enable_gvt, i915.enable_gvt, bool, 0400);
 MODULE_PARM_DESC(enable_gvt,
 	"Enable support for Intel GVT-g graphics virtualization host support(default:false)");
-
-module_param_named_unsafe(enable_dbc, i915.enable_dbc, bool, 0600);
-MODULE_PARM_DESC(enable_dbc,
-	"Enable support for dynamic backlight control (default:true)");
diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index 057e203e6bda..0d6cf9138dc4 100644
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -67,8 +67,7 @@
 	func(bool, verbose_state_checks); \
 	func(bool, nuclear_pageflip); \
 	func(bool, enable_dp_mst); \
-	func(bool, enable_gvt); \
-	func(bool, enable_dbc)
+	func(bool, enable_gvt)
 
 #define MEMBER(T, member) T member
 struct i915_params {
diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
index b25cd88fc1c5..fea161727c6e 100644
--- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
@@ -173,24 +173,6 @@ static bool intel_dp_aux_set_pwm_freq(struct intel_connector *connector)
 	return true;
 }
 
-/*
-* Set minimum / maximum dynamic brightness percentage. This value is expressed
-* as the percentage of normal brightness in 5% increments.
-*/
-static bool
-intel_dp_aux_set_dynamic_backlight_percent(struct intel_dp *intel_dp,
-					   u32 min, u32 max)
-{
-	u8 dbc[] = { DIV_ROUND_CLOSEST(min, 5), DIV_ROUND_CLOSEST(max, 5) };
-
-	if (drm_dp_dpcd_write(&intel_dp->aux, DP_EDP_DBC_MINIMUM_BRIGHTNESS_SET,
-			  dbc, sizeof(dbc)) < 0) {
-		DRM_DEBUG_KMS("Failed to write aux DBC brightness level\n");
-		return false;
-	}
-	return true;
-}
-
 static void intel_dp_aux_enable_backlight(const struct intel_crtc_state *crtc_state,
 					  const struct drm_connector_state *conn_state)
 {
@@ -226,14 +208,6 @@ static void intel_dp_aux_enable_backlight(const struct intel_crtc_state *crtc_st
 		if (intel_dp_aux_set_pwm_freq(connector))
 			new_dpcd_buf |= DP_EDP_BACKLIGHT_FREQ_AUX_SET_ENABLE;
 
-	if (i915.enable_dbc &&
-	    (intel_dp->edp_dpcd[2] & DP_EDP_DYNAMIC_BACKLIGHT_CAP)) {
-		if(intel_dp_aux_set_dynamic_backlight_percent(intel_dp, 0, 100)) {
-			new_dpcd_buf |= DP_EDP_DYNAMIC_BACKLIGHT_ENABLE;
-			DRM_DEBUG_KMS("Enable dynamic brightness.\n");
-		}
-	}
-
 	if (new_dpcd_buf != dpcd_buf) {
 		if (drm_dp_dpcd_writeb(&intel_dp->aux,
 			DP_EDP_BACKLIGHT_MODE_SET_REGISTER, new_dpcd_buf) < 0) {
-- 
2.11.0

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[PATCH 2/2] Revert "drm/i915: Add heuristic to determine better way to adjust brightness"

[Jani Nikula]

This reverts commit 560a758d39c616f83ac25ff6e0816a49ebe6401c.

The DPCD backlight commits regress a Thinkpad X1 Carbon 4th Gen and a
BXT-P (in CI). Enabling dynamic backlight boots to a black screen, and
enabling DPCD backlight leads to a black screen after suspend/resume.

References: http://mid.mail-archive.com/20170706135349.6tu3lz7uehazlnnn@boom
References: http://mid.mail-archive.com/20170627132326.f2q3yn4bh5flji4q@boom
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101619
Reported-by: David Weinehall <david.weinehall@linux.intel.com>
Fixes: 560a758d39c6 ("drm/i915: Add heuristic to determine better way to adjust brightness")
Cc: Jenny TC <jenny.tc@intel.com>
Cc: David Weinehall <david.weinehall@linux.intel.com>
Cc: Puthikorn Voravootivat <puthik@chromium.org>
Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: intel-gfx@lists.freedesktop.org
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
 drivers/gpu/drm/i915/i915_params.c            |  7 ++-
 drivers/gpu/drm/i915/i915_params.h            |  2 +-
 drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 61 ++-------------------------
 3 files changed, 7 insertions(+), 63 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 5b5ab15d191f..14e2c2e57f96 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -63,7 +63,7 @@ struct i915_params i915 __read_mostly = {
 	.huc_firmware_path = NULL,
 	.enable_dp_mst = true,
 	.inject_load_failure = 0,
-	.enable_dpcd_backlight = -1,
+	.enable_dpcd_backlight = false,
 	.enable_gvt = false,
 };
 
@@ -246,10 +246,9 @@ MODULE_PARM_DESC(enable_dp_mst,
 module_param_named_unsafe(inject_load_failure, i915.inject_load_failure, uint, 0400);
 MODULE_PARM_DESC(inject_load_failure,
 	"Force an error after a number of failure check points (0:disabled (default), N:force failure at the Nth failure check point)");
-module_param_named_unsafe(enable_dpcd_backlight, i915.enable_dpcd_backlight, int, 0600);
+module_param_named(enable_dpcd_backlight, i915.enable_dpcd_backlight, bool, 0600);
 MODULE_PARM_DESC(enable_dpcd_backlight,
-	"Enable support for DPCD backlight control "
-	"(-1:auto (default), 0:force disable, 1:force enabled if supported");
+	"Enable support for DPCD backlight control (default:false)");
 
 module_param_named(enable_gvt, i915.enable_gvt, bool, 0400);
 MODULE_PARM_DESC(enable_gvt,
diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index 0d6cf9138dc4..febbfdbd30bd 100644
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -53,7 +53,6 @@
 	func(int, edp_vswing); \
 	func(int, reset); \
 	func(unsigned int, inject_load_failure); \
-	func(int, enable_dpcd_backlight); \
 	/* leave bools at the end to not create holes */ \
 	func(bool, alpha_support); \
 	func(bool, enable_cmd_parser); \
@@ -67,6 +66,7 @@
 	func(bool, verbose_state_checks); \
 	func(bool, nuclear_pageflip); \
 	func(bool, enable_dp_mst); \
+	func(bool, enable_dpcd_backlight); \
 	func(bool, enable_gvt)
 
 #define MEMBER(T, member) T member
diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
index fea161727c6e..d2830ba3162e 100644
--- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
@@ -251,66 +251,15 @@ intel_dp_aux_display_control_capable(struct intel_connector *connector)
 	/* Check the eDP Display control capabilities registers to determine if
 	 * the panel can support backlight control over the aux channel
 	 */
-	if ((intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP) &&
-	    (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP)) {
+	if (intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP &&
+	    (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP) &&
+	    !(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP)) {
 		DRM_DEBUG_KMS("AUX Backlight Control Supported!\n");
 		return true;
 	}
 	return false;
 }
 
-/*
- * Heuristic function whether we should use AUX for backlight adjustment or not.
- *
- * We should use AUX for backlight brightness adjustment if panel doesn't this
- * via PWM pin or using AUX is better than using PWM pin.
- *
- * The heuristic to determine that using AUX pin is better than using PWM pin is
- * that the panel support any of the feature list here.
- * - Regional backlight brightness adjustment
- * - Backlight PWM frequency set
- * - More than 8 bits resolution of brightness level
- * - Backlight enablement via AUX and not by BL_ENABLE pin
- *
- * If all above are not true, assume that using PWM pin is better.
- */
-static bool
-intel_dp_aux_display_control_heuristic(struct intel_connector *connector)
-{
-	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
-	uint8_t reg_val;
-
-	/* Panel doesn't support adjusting backlight brightness via PWN pin */
-	if (!(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP))
-		return true;
-
-	/* Panel supports regional backlight brightness adjustment */
-	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_GENERAL_CAP_3,
-			      &reg_val) != 1) {
-		DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
-			       DP_EDP_GENERAL_CAP_3);
-		return false;
-	}
-	if (reg_val > 0)
-		return true;
-
-	/* Panel supports backlight PWM frequency set */
-	if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_FREQ_AUX_SET_CAP)
-		return true;
-
-	/* Panel supports more than 8 bits resolution of brightness level */
-	if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
-		return true;
-
-	/* Panel supports enabling backlight via AUX but not by BL_ENABLE pin */
-	if ((intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP) &&
-	    !(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_PIN_ENABLE_CAP))
-		return true;
-
-	return false;
-
-}
-
 int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
 {
 	struct intel_panel *panel = &intel_connector->panel;
@@ -321,10 +270,6 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
 	if (!intel_dp_aux_display_control_capable(intel_connector))
 		return -ENODEV;
 
-	if (i915.enable_dpcd_backlight == -1 &&
-	    !intel_dp_aux_display_control_heuristic(intel_connector))
-		return -ENODEV;
-
 	panel->backlight.setup = intel_dp_aux_setup_backlight;
 	panel->backlight.enable = intel_dp_aux_enable_backlight;
 	panel->backlight.disable = intel_dp_aux_disable_backlight;
-- 
2.11.0

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Re: [PATCH 2/2] Revert "drm/i915: Add heuristic to determine better way to adjust brightness"

[Pandiyan, Dhinakaran]

On Thu, 2017-07-20 at 12:25 +0300, Jani Nikula wrote:
> This reverts commit 560a758d39c616f83ac25ff6e0816a49ebe6401c.
> 
> The DPCD backlight commits regress a Thinkpad X1 Carbon 4th Gen and a
> BXT-P (in CI). Enabling dynamic backlight boots to a black screen, and
> enabling DPCD backlight leads to a black screen after suspend/resume.
> 


Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com> for
both patches.

> References: http://mid.mail-archive.com/20170706135349.6tu3lz7uehazlnnn@boom
> References: http://mid.mail-archive.com/20170627132326.f2q3yn4bh5flji4q@boom
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101619
> Reported-by: David Weinehall <david.weinehall@linux.intel.com>
> Fixes: 560a758d39c6 ("drm/i915: Add heuristic to determine better way to adjust brightness")
> Cc: Jenny TC <jenny.tc@intel.com>
> Cc: David Weinehall <david.weinehall@linux.intel.com>
> Cc: Puthikorn Voravootivat <puthik@chromium.org>
> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: intel-gfx@lists.freedesktop.org
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_params.c            |  7 ++-
>  drivers/gpu/drm/i915/i915_params.h            |  2 +-
>  drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 61 ++-------------------------
>  3 files changed, 7 insertions(+), 63 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> index 5b5ab15d191f..14e2c2e57f96 100644
> --- a/drivers/gpu/drm/i915/i915_params.c
> +++ b/drivers/gpu/drm/i915/i915_params.c
> @@ -63,7 +63,7 @@ struct i915_params i915 __read_mostly = {
>  	.huc_firmware_path = NULL,
>  	.enable_dp_mst = true,
>  	.inject_load_failure = 0,
> -	.enable_dpcd_backlight = -1,
> +	.enable_dpcd_backlight = false,
>  	.enable_gvt = false,
>  };
>  
> @@ -246,10 +246,9 @@ MODULE_PARM_DESC(enable_dp_mst,
>  module_param_named_unsafe(inject_load_failure, i915.inject_load_failure, uint, 0400);
>  MODULE_PARM_DESC(inject_load_failure,
>  	"Force an error after a number of failure check points (0:disabled (default), N:force failure at the Nth failure check point)");
> -module_param_named_unsafe(enable_dpcd_backlight, i915.enable_dpcd_backlight, int, 0600);
> +module_param_named(enable_dpcd_backlight, i915.enable_dpcd_backlight, bool, 0600);
>  MODULE_PARM_DESC(enable_dpcd_backlight,
> -	"Enable support for DPCD backlight control "
> -	"(-1:auto (default), 0:force disable, 1:force enabled if supported");
> +	"Enable support for DPCD backlight control (default:false)");
>  
>  module_param_named(enable_gvt, i915.enable_gvt, bool, 0400);
>  MODULE_PARM_DESC(enable_gvt,
> diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
> index 0d6cf9138dc4..febbfdbd30bd 100644
> --- a/drivers/gpu/drm/i915/i915_params.h
> +++ b/drivers/gpu/drm/i915/i915_params.h
> @@ -53,7 +53,6 @@
>  	func(int, edp_vswing); \
>  	func(int, reset); \
>  	func(unsigned int, inject_load_failure); \
> -	func(int, enable_dpcd_backlight); \
>  	/* leave bools at the end to not create holes */ \
>  	func(bool, alpha_support); \
>  	func(bool, enable_cmd_parser); \
> @@ -67,6 +66,7 @@
>  	func(bool, verbose_state_checks); \
>  	func(bool, nuclear_pageflip); \
>  	func(bool, enable_dp_mst); \
> +	func(bool, enable_dpcd_backlight); \
>  	func(bool, enable_gvt)
>  
>  #define MEMBER(T, member) T member
> diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> index fea161727c6e..d2830ba3162e 100644
> --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> @@ -251,66 +251,15 @@ intel_dp_aux_display_control_capable(struct intel_connector *connector)
>  	/* Check the eDP Display control capabilities registers to determine if
>  	 * the panel can support backlight control over the aux channel
>  	 */
> -	if ((intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP) &&
> -	    (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP)) {
> +	if (intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP &&
> +	    (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP) &&
> +	    !(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP)) {
>  		DRM_DEBUG_KMS("AUX Backlight Control Supported!\n");
>  		return true;
>  	}
>  	return false;
>  }
>  
> -/*
> - * Heuristic function whether we should use AUX for backlight adjustment or not.
> - *
> - * We should use AUX for backlight brightness adjustment if panel doesn't this
> - * via PWM pin or using AUX is better than using PWM pin.
> - *
> - * The heuristic to determine that using AUX pin is better than using PWM pin is
> - * that the panel support any of the feature list here.
> - * - Regional backlight brightness adjustment
> - * - Backlight PWM frequency set
> - * - More than 8 bits resolution of brightness level
> - * - Backlight enablement via AUX and not by BL_ENABLE pin
> - *
> - * If all above are not true, assume that using PWM pin is better.
> - */
> -static bool
> -intel_dp_aux_display_control_heuristic(struct intel_connector *connector)
> -{
> -	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
> -	uint8_t reg_val;
> -
> -	/* Panel doesn't support adjusting backlight brightness via PWN pin */
> -	if (!(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP))
> -		return true;
> -
> -	/* Panel supports regional backlight brightness adjustment */
> -	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_GENERAL_CAP_3,
> -			      &reg_val) != 1) {
> -		DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
> -			       DP_EDP_GENERAL_CAP_3);
> -		return false;
> -	}
> -	if (reg_val > 0)
> -		return true;
> -
> -	/* Panel supports backlight PWM frequency set */
> -	if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_FREQ_AUX_SET_CAP)
> -		return true;
> -
> -	/* Panel supports more than 8 bits resolution of brightness level */
> -	if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
> -		return true;
> -
> -	/* Panel supports enabling backlight via AUX but not by BL_ENABLE pin */
> -	if ((intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP) &&
> -	    !(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_PIN_ENABLE_CAP))
> -		return true;
> -
> -	return false;
> -
> -}
> -
>  int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
>  {
>  	struct intel_panel *panel = &intel_connector->panel;
> @@ -321,10 +270,6 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
>  	if (!intel_dp_aux_display_control_capable(intel_connector))
>  		return -ENODEV;
>  
> -	if (i915.enable_dpcd_backlight == -1 &&
> -	    !intel_dp_aux_display_control_heuristic(intel_connector))
> -		return -ENODEV;
> -
>  	panel->backlight.setup = intel_dp_aux_setup_backlight;
>  	panel->backlight.enable = intel_dp_aux_enable_backlight;
>  	panel->backlight.disable = intel_dp_aux_disable_backlight;
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Re: [PATCH 2/2] Revert "drm/i915: Add heuristic to determine better way to adjust brightness"

[Jani Nikula]

On Thu, 20 Jul 2017, "Pandiyan, Dhinakaran" <dhinakaran.pandiyan@intel.com> wrote:
> On Thu, 2017-07-20 at 12:25 +0300, Jani Nikula wrote:
>> This reverts commit 560a758d39c616f83ac25ff6e0816a49ebe6401c.
>> 
>> The DPCD backlight commits regress a Thinkpad X1 Carbon 4th Gen and a
>> BXT-P (in CI). Enabling dynamic backlight boots to a black screen, and
>> enabling DPCD backlight leads to a black screen after suspend/resume.
>> 
>
>
> Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com> for
> both patches.

Thanks for the review, both pushed, with Daniel's IRC ack on top.

BR,
Jani.

>
>> References: http://mid.mail-archive.com/20170706135349.6tu3lz7uehazlnnn@boom
>> References: http://mid.mail-archive.com/20170627132326.f2q3yn4bh5flji4q@boom
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101619
>> Reported-by: David Weinehall <david.weinehall@linux.intel.com>
>> Fixes: 560a758d39c6 ("drm/i915: Add heuristic to determine better way to adjust brightness")
>> Cc: Jenny TC <jenny.tc@intel.com>
>> Cc: David Weinehall <david.weinehall@linux.intel.com>
>> Cc: Puthikorn Voravootivat <puthik@chromium.org>
>> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
>> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>> Cc: intel-gfx@lists.freedesktop.org
>> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
>> ---
>>  drivers/gpu/drm/i915/i915_params.c            |  7 ++-
>>  drivers/gpu/drm/i915/i915_params.h            |  2 +-
>>  drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 61 ++-------------------------
>>  3 files changed, 7 insertions(+), 63 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
>> index 5b5ab15d191f..14e2c2e57f96 100644
>> --- a/drivers/gpu/drm/i915/i915_params.c
>> +++ b/drivers/gpu/drm/i915/i915_params.c
>> @@ -63,7 +63,7 @@ struct i915_params i915 __read_mostly = {
>>  	.huc_firmware_path = NULL,
>>  	.enable_dp_mst = true,
>>  	.inject_load_failure = 0,
>> -	.enable_dpcd_backlight = -1,
>> +	.enable_dpcd_backlight = false,
>>  	.enable_gvt = false,
>>  };
>>  
>> @@ -246,10 +246,9 @@ MODULE_PARM_DESC(enable_dp_mst,
>>  module_param_named_unsafe(inject_load_failure, i915.inject_load_failure, uint, 0400);
>>  MODULE_PARM_DESC(inject_load_failure,
>>  	"Force an error after a number of failure check points (0:disabled (default), N:force failure at the Nth failure check point)");
>> -module_param_named_unsafe(enable_dpcd_backlight, i915.enable_dpcd_backlight, int, 0600);
>> +module_param_named(enable_dpcd_backlight, i915.enable_dpcd_backlight, bool, 0600);
>>  MODULE_PARM_DESC(enable_dpcd_backlight,
>> -	"Enable support for DPCD backlight control "
>> -	"(-1:auto (default), 0:force disable, 1:force enabled if supported");
>> +	"Enable support for DPCD backlight control (default:false)");
>>  
>>  module_param_named(enable_gvt, i915.enable_gvt, bool, 0400);
>>  MODULE_PARM_DESC(enable_gvt,
>> diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
>> index 0d6cf9138dc4..febbfdbd30bd 100644
>> --- a/drivers/gpu/drm/i915/i915_params.h
>> +++ b/drivers/gpu/drm/i915/i915_params.h
>> @@ -53,7 +53,6 @@
>>  	func(int, edp_vswing); \
>>  	func(int, reset); \
>>  	func(unsigned int, inject_load_failure); \
>> -	func(int, enable_dpcd_backlight); \
>>  	/* leave bools at the end to not create holes */ \
>>  	func(bool, alpha_support); \
>>  	func(bool, enable_cmd_parser); \
>> @@ -67,6 +66,7 @@
>>  	func(bool, verbose_state_checks); \
>>  	func(bool, nuclear_pageflip); \
>>  	func(bool, enable_dp_mst); \
>> +	func(bool, enable_dpcd_backlight); \
>>  	func(bool, enable_gvt)
>>  
>>  #define MEMBER(T, member) T member
>> diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
>> index fea161727c6e..d2830ba3162e 100644
>> --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
>> +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
>> @@ -251,66 +251,15 @@ intel_dp_aux_display_control_capable(struct intel_connector *connector)
>>  	/* Check the eDP Display control capabilities registers to determine if
>>  	 * the panel can support backlight control over the aux channel
>>  	 */
>> -	if ((intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP) &&
>> -	    (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP)) {
>> +	if (intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP &&
>> +	    (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP) &&
>> +	    !(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP)) {
>>  		DRM_DEBUG_KMS("AUX Backlight Control Supported!\n");
>>  		return true;
>>  	}
>>  	return false;
>>  }
>>  
>> -/*
>> - * Heuristic function whether we should use AUX for backlight adjustment or not.
>> - *
>> - * We should use AUX for backlight brightness adjustment if panel doesn't this
>> - * via PWM pin or using AUX is better than using PWM pin.
>> - *
>> - * The heuristic to determine that using AUX pin is better than using PWM pin is
>> - * that the panel support any of the feature list here.
>> - * - Regional backlight brightness adjustment
>> - * - Backlight PWM frequency set
>> - * - More than 8 bits resolution of brightness level
>> - * - Backlight enablement via AUX and not by BL_ENABLE pin
>> - *
>> - * If all above are not true, assume that using PWM pin is better.
>> - */
>> -static bool
>> -intel_dp_aux_display_control_heuristic(struct intel_connector *connector)
>> -{
>> -	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
>> -	uint8_t reg_val;
>> -
>> -	/* Panel doesn't support adjusting backlight brightness via PWN pin */
>> -	if (!(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP))
>> -		return true;
>> -
>> -	/* Panel supports regional backlight brightness adjustment */
>> -	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_GENERAL_CAP_3,
>> -			      &reg_val) != 1) {
>> -		DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
>> -			       DP_EDP_GENERAL_CAP_3);
>> -		return false;
>> -	}
>> -	if (reg_val > 0)
>> -		return true;
>> -
>> -	/* Panel supports backlight PWM frequency set */
>> -	if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_FREQ_AUX_SET_CAP)
>> -		return true;
>> -
>> -	/* Panel supports more than 8 bits resolution of brightness level */
>> -	if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
>> -		return true;
>> -
>> -	/* Panel supports enabling backlight via AUX but not by BL_ENABLE pin */
>> -	if ((intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP) &&
>> -	    !(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_PIN_ENABLE_CAP))
>> -		return true;
>> -
>> -	return false;
>> -
>> -}
>> -
>>  int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
>>  {
>>  	struct intel_panel *panel = &intel_connector->panel;
>> @@ -321,10 +270,6 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
>>  	if (!intel_dp_aux_display_control_capable(intel_connector))
>>  		return -ENODEV;
>>  
>> -	if (i915.enable_dpcd_backlight == -1 &&
>> -	    !intel_dp_aux_display_control_heuristic(intel_connector))
>> -		return -ENODEV;
>> -
>>  	panel->backlight.setup = intel_dp_aux_setup_backlight;
>>  	panel->backlight.enable = intel_dp_aux_enable_backlight;
>>  	panel->backlight.disable = intel_dp_aux_disable_backlight;

-- 
Jani Nikula, Intel Open Source Technology Center
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✓ Fi.CI.BAT: success for drm/i915: revert DPCD backlight and DBC enabling by default

[Patchwork]

== Series Details ==

Series: drm/i915: revert DPCD backlight and DBC enabling by default
URL   : https://patchwork.freedesktop.org/series/27623/
State : success

== Summary ==

Series 27623v1 drm/i915: revert DPCD backlight and DBC enabling by default
https://patchwork.freedesktop.org/api/1.0/series/27623/revisions/1/mbox/

Test gem_exec_flush:
        Subgroup basic-batch-kernel-default-uc:
                pass       -> FAIL       (fi-snb-2600) fdo#100007
Test kms_cursor_legacy:
        Subgroup basic-busy-flip-before-cursor-atomic:
                fail       -> PASS       (fi-snb-2600) fdo#100215

fdo#100007 https://bugs.freedesktop.org/show_bug.cgi?id=100007
fdo#100215 https://bugs.freedesktop.org/show_bug.cgi?id=100215

fi-bdw-5557u     total:279  pass:268  dwarn:0   dfail:0   fail:0   skip:11  time:445s
fi-bdw-gvtdvm    total:279  pass:265  dwarn:0   dfail:0   fail:0   skip:14  time:431s
fi-blb-e6850     total:279  pass:224  dwarn:1   dfail:0   fail:0   skip:54  time:353s
fi-bsw-n3050     total:279  pass:243  dwarn:0   dfail:0   fail:0   skip:36  time:538s
fi-bxt-j4205     total:279  pass:260  dwarn:0   dfail:0   fail:0   skip:19  time:514s
fi-byt-j1900     total:279  pass:254  dwarn:1   dfail:0   fail:0   skip:24  time:486s
fi-byt-n2820     total:279  pass:250  dwarn:1   dfail:0   fail:0   skip:28  time:487s
fi-glk-2a        total:279  pass:260  dwarn:0   dfail:0   fail:0   skip:19  time:602s
fi-hsw-4770      total:279  pass:263  dwarn:0   dfail:0   fail:0   skip:16  time:435s
fi-hsw-4770r     total:279  pass:263  dwarn:0   dfail:0   fail:0   skip:16  time:414s
fi-ilk-650       total:279  pass:229  dwarn:0   dfail:0   fail:0   skip:50  time:412s
fi-ivb-3520m     total:279  pass:261  dwarn:0   dfail:0   fail:0   skip:18  time:501s
fi-ivb-3770      total:279  pass:261  dwarn:0   dfail:0   fail:0   skip:18  time:476s
fi-kbl-7500u     total:279  pass:261  dwarn:0   dfail:0   fail:0   skip:18  time:475s
fi-kbl-7560u     total:279  pass:269  dwarn:0   dfail:0   fail:0   skip:10  time:579s
fi-kbl-r         total:279  pass:261  dwarn:0   dfail:0   fail:0   skip:18  time:579s
fi-pnv-d510      total:279  pass:222  dwarn:2   dfail:0   fail:0   skip:55  time:560s
fi-skl-6260u     total:279  pass:269  dwarn:0   dfail:0   fail:0   skip:10  time:468s
fi-skl-6700hq    total:279  pass:262  dwarn:0   dfail:0   fail:0   skip:17  time:585s
fi-skl-6700k     total:279  pass:261  dwarn:0   dfail:0   fail:0   skip:18  time:469s
fi-skl-6770hq    total:279  pass:269  dwarn:0   dfail:0   fail:0   skip:10  time:482s
fi-skl-gvtdvm    total:279  pass:266  dwarn:0   dfail:0   fail:0   skip:13  time:435s
fi-skl-x1585l    total:279  pass:269  dwarn:0   dfail:0   fail:0   skip:10  time:497s
fi-snb-2520m     total:279  pass:251  dwarn:0   dfail:0   fail:0   skip:28  time:539s
fi-snb-2600      total:279  pass:249  dwarn:0   dfail:0   fail:1   skip:29  time:407s

948c3bddb3333e7245970c684749ba5d72370cd2 drm-tip: 2017y-07m-20d-10h-52m-43s UTC integration manifest
682e3e2 Revert "drm/i915: Add heuristic to determine better way to adjust brightness"
70cbf1b Revert "drm/i915: Add option to support dynamic backlight via DPCD"

== Logs ==

For more details see: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_5244/
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