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

Pandiyan, Dhinakaran dhinakaran.pandiyan at intel.com
Thu Jul 20 20:23:03 UTC 2017




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 at 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 at linux.intel.com>
> Fixes: 560a758d39c6 ("drm/i915: Add heuristic to determine better way to adjust brightness")
> Cc: Jenny TC <jenny.tc at intel.com>
> Cc: David Weinehall <david.weinehall at linux.intel.com>
> Cc: Puthikorn Voravootivat <puthik at chromium.org>
> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: intel-gfx at lists.freedesktop.org
> Signed-off-by: Jani Nikula <jani.nikula at 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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