drm/i915/dp: revert back to max link rate and lane count on eDP

Submitted by Jani Nikula on April 5, 2019, 7:24 a.m.

Details

Message ID 20190405072439.8922-1-jani.nikula@intel.com
State New
Headers show
Series "drm/i915/dp: revert back to max link rate and lane count on eDP" ( rev: 1 ) in Intel GFX

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Commit Message

Jani Nikula April 5, 2019, 7:24 a.m.
Commit 7769db588384 ("drm/i915/dp: optimize eDP 1.4+ link config fast
and narrow") started to optize the eDP 1.4+ link config, both per spec
and as preparation for display stream compression support.

Sadly, we again face panels that flat out fail with parameters they
claim to support. Revert, and go back to the drawing board.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109959
Fixes: 7769db588384 ("drm/i915/dp: optimize eDP 1.4+ link config fast and narrow")
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Matt Atwood <matthew.s.atwood@intel.com>
Cc: "Lee, Shawn C" <shawn.c.lee@intel.com>
Cc: Dave Airlie <airlied@gmail.com>
Cc: intel-gfx@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v5.0+
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 67 +++++----------------------------
 1 file changed, 9 insertions(+), 58 deletions(-)

Patch hide | download patch | download mbox

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 72c490..fd0f53 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1856,42 +1856,6 @@  intel_dp_compute_link_config_wide(struct intel_dp *intel_dp,
 	return -EINVAL;
 }
 
-/* Optimize link config in order: max bpp, min lanes, min clock */
-static int
-intel_dp_compute_link_config_fast(struct intel_dp *intel_dp,
-				  struct intel_crtc_state *pipe_config,
-				  const struct link_config_limits *limits)
-{
-	struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;
-	int bpp, clock, lane_count;
-	int mode_rate, link_clock, link_avail;
-
-	for (bpp = limits->max_bpp; bpp >= limits->min_bpp; bpp -= 2 * 3) {
-		mode_rate = intel_dp_link_required(adjusted_mode->crtc_clock,
-						   bpp);
-
-		for (lane_count = limits->min_lane_count;
-		     lane_count <= limits->max_lane_count;
-		     lane_count <<= 1) {
-			for (clock = limits->min_clock; clock <= limits->max_clock; clock++) {
-				link_clock = intel_dp->common_rates[clock];
-				link_avail = intel_dp_max_data_rate(link_clock,
-								    lane_count);
-
-				if (mode_rate <= link_avail) {
-					pipe_config->lane_count = lane_count;
-					pipe_config->pipe_bpp = bpp;
-					pipe_config->port_clock = link_clock;
-
-					return 0;
-				}
-			}
-		}
-	}
-
-	return -EINVAL;
-}
-
 static int intel_dp_dsc_compute_bpp(struct intel_dp *intel_dp, u8 dsc_max_bpc)
 {
 	int i, num_bpc;
@@ -2031,12 +1995,10 @@  intel_dp_compute_link_config(struct intel_encoder *encoder,
 	if (intel_dp_is_edp(intel_dp) && intel_dp->edp_dpcd[0] < DP_EDP_14) {
 		/*
 		 * Use the maximum clock and number of lanes the eDP panel
-		 * advertizes being capable of. The eDP 1.3 and earlier panels
-		 * are generally designed to support only a single clock and
-		 * lane configuration, and typically these values correspond to
-		 * the native resolution of the panel. With eDP 1.4 rate select
-		 * and DSC, this is decreasingly the case, and we need to be
-		 * able to select less than maximum link config.
+		 * advertizes being capable of. The panels are generally
+		 * designed to support only a single clock and lane
+		 * configuration, and typically these values correspond to the
+		 * native resolution of the panel.
 		 */
 		limits.min_lane_count = limits.max_lane_count;
 		limits.min_clock = limits.max_clock;
@@ -2050,22 +2012,11 @@  intel_dp_compute_link_config(struct intel_encoder *encoder,
 		      intel_dp->common_rates[limits.max_clock],
 		      limits.max_bpp, adjusted_mode->crtc_clock);
 
-	if (intel_dp_is_edp(intel_dp))
-		/*
-		 * Optimize for fast and narrow. eDP 1.3 section 3.3 and eDP 1.4
-		 * section A.1: "It is recommended that the minimum number of
-		 * lanes be used, using the minimum link rate allowed for that
-		 * lane configuration."
-		 *
-		 * Note that we use the max clock and lane count for eDP 1.3 and
-		 * earlier, and fast vs. wide is irrelevant.
-		 */
-		ret = intel_dp_compute_link_config_fast(intel_dp, pipe_config,
-							&limits);
-	else
-		/* Optimize for slow and wide. */
-		ret = intel_dp_compute_link_config_wide(intel_dp, pipe_config,
-							&limits);
+	/*
+	 * Optimize for slow and wide. This is the place to add alternative
+	 * optimization policy.
+	 */
+	ret = intel_dp_compute_link_config_wide(intel_dp, pipe_config, &limits);
 
 	/* enable compression if the mode doesn't fit available BW */
 	DRM_DEBUG_KMS("Force DSC en = %d\n", intel_dp->force_dsc_en);

Comments

On Fri, 05 Apr 2019, Jani Nikula <jani.nikula@intel.com> wrote:
> Commit 7769db588384 ("drm/i915/dp: optimize eDP 1.4+ link config fast
> and narrow") started to optize the eDP 1.4+ link config, both per spec
> and as preparation for display stream compression support.
>
> Sadly, we again face panels that flat out fail with parameters they
> claim to support. Revert, and go back to the drawing board.

Fail, this one actually reverts back to wide-and-slow, while retaining
the use of optimal parameters rather than maxing them out.

It's a data point, but we'll want the full revert now.

BR,
Jani.

>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109959
> Fixes: 7769db588384 ("drm/i915/dp: optimize eDP 1.4+ link config fast and narrow")
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Manasi Navare <manasi.d.navare@intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Cc: Matt Atwood <matthew.s.atwood@intel.com>
> Cc: "Lee, Shawn C" <shawn.c.lee@intel.com>
> Cc: Dave Airlie <airlied@gmail.com>
> Cc: intel-gfx@lists.freedesktop.org
> Cc: <stable@vger.kernel.org> # v5.0+
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c | 67 +++++----------------------------
>  1 file changed, 9 insertions(+), 58 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 72c490..fd0f53 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -1856,42 +1856,6 @@ intel_dp_compute_link_config_wide(struct intel_dp *intel_dp,
>  	return -EINVAL;
>  }
>  
> -/* Optimize link config in order: max bpp, min lanes, min clock */
> -static int
> -intel_dp_compute_link_config_fast(struct intel_dp *intel_dp,
> -				  struct intel_crtc_state *pipe_config,
> -				  const struct link_config_limits *limits)
> -{
> -	struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;
> -	int bpp, clock, lane_count;
> -	int mode_rate, link_clock, link_avail;
> -
> -	for (bpp = limits->max_bpp; bpp >= limits->min_bpp; bpp -= 2 * 3) {
> -		mode_rate = intel_dp_link_required(adjusted_mode->crtc_clock,
> -						   bpp);
> -
> -		for (lane_count = limits->min_lane_count;
> -		     lane_count <= limits->max_lane_count;
> -		     lane_count <<= 1) {
> -			for (clock = limits->min_clock; clock <= limits->max_clock; clock++) {
> -				link_clock = intel_dp->common_rates[clock];
> -				link_avail = intel_dp_max_data_rate(link_clock,
> -								    lane_count);
> -
> -				if (mode_rate <= link_avail) {
> -					pipe_config->lane_count = lane_count;
> -					pipe_config->pipe_bpp = bpp;
> -					pipe_config->port_clock = link_clock;
> -
> -					return 0;
> -				}
> -			}
> -		}
> -	}
> -
> -	return -EINVAL;
> -}
> -
>  static int intel_dp_dsc_compute_bpp(struct intel_dp *intel_dp, u8 dsc_max_bpc)
>  {
>  	int i, num_bpc;
> @@ -2031,12 +1995,10 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
>  	if (intel_dp_is_edp(intel_dp) && intel_dp->edp_dpcd[0] < DP_EDP_14) {
>  		/*
>  		 * Use the maximum clock and number of lanes the eDP panel
> -		 * advertizes being capable of. The eDP 1.3 and earlier panels
> -		 * are generally designed to support only a single clock and
> -		 * lane configuration, and typically these values correspond to
> -		 * the native resolution of the panel. With eDP 1.4 rate select
> -		 * and DSC, this is decreasingly the case, and we need to be
> -		 * able to select less than maximum link config.
> +		 * advertizes being capable of. The panels are generally
> +		 * designed to support only a single clock and lane
> +		 * configuration, and typically these values correspond to the
> +		 * native resolution of the panel.
>  		 */
>  		limits.min_lane_count = limits.max_lane_count;
>  		limits.min_clock = limits.max_clock;
> @@ -2050,22 +2012,11 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
>  		      intel_dp->common_rates[limits.max_clock],
>  		      limits.max_bpp, adjusted_mode->crtc_clock);
>  
> -	if (intel_dp_is_edp(intel_dp))
> -		/*
> -		 * Optimize for fast and narrow. eDP 1.3 section 3.3 and eDP 1.4
> -		 * section A.1: "It is recommended that the minimum number of
> -		 * lanes be used, using the minimum link rate allowed for that
> -		 * lane configuration."
> -		 *
> -		 * Note that we use the max clock and lane count for eDP 1.3 and
> -		 * earlier, and fast vs. wide is irrelevant.
> -		 */
> -		ret = intel_dp_compute_link_config_fast(intel_dp, pipe_config,
> -							&limits);
> -	else
> -		/* Optimize for slow and wide. */
> -		ret = intel_dp_compute_link_config_wide(intel_dp, pipe_config,
> -							&limits);
> +	/*
> +	 * Optimize for slow and wide. This is the place to add alternative
> +	 * optimization policy.
> +	 */
> +	ret = intel_dp_compute_link_config_wide(intel_dp, pipe_config, &limits);
>  
>  	/* enable compression if the mode doesn't fit available BW */
>  	DRM_DEBUG_KMS("Force DSC en = %d\n", intel_dp->force_dsc_en);