drm/i915/dp: Add DSC BPC/BPP constraints while selecting pipe bpp with DSC

Currently we check if the pipe_bpp selected is >= the
min DSC bpc/bpp requirement. We do not check if it is <= the max DSC
bpc/bpp requirement.

Add checks for max DSC BPC/BPP constraints while computing the
pipe_bpp when DSC is in use.

v2: Fix the commit message.
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230817142459.89764-15-ankit.k.nautiyal@intel.com

drivers/gpu/drm/i915/display/intel_dp.c

@@ -1691,13 +1691,27 @@ u8 intel_dp_dsc_min_src_input_bpc(struct drm_i915_private *i915)
 }
 
 static
-bool is_dsc_pipe_bpp_sufficient(struct drm_i915_private *i915, int pipe_bpp)
+bool is_dsc_pipe_bpp_sufficient(struct drm_i915_private *i915,
+				struct drm_connector_state *conn_state,
+				struct link_config_limits *limits,
+				int pipe_bpp)
 {
-	return pipe_bpp >= intel_dp_dsc_min_src_input_bpc(i915) * 3;
+	u8 dsc_max_bpc, dsc_min_bpc, dsc_max_pipe_bpp, dsc_min_pipe_bpp;
+
+	dsc_max_bpc = min(intel_dp_dsc_max_src_input_bpc(i915), conn_state->max_requested_bpc);
+	dsc_min_bpc = intel_dp_dsc_min_src_input_bpc(i915);
+
+	dsc_max_pipe_bpp = min(dsc_max_bpc * 3, limits->max_bpp);
+	dsc_min_pipe_bpp = max(dsc_min_bpc * 3, limits->min_bpp);
+
+	return pipe_bpp >= dsc_min_pipe_bpp &&
+	       pipe_bpp <= dsc_max_pipe_bpp;
 }
 
 static
-int intel_dp_force_dsc_pipe_bpp(struct intel_dp *intel_dp)
+int intel_dp_force_dsc_pipe_bpp(struct intel_dp *intel_dp,
+				struct drm_connector_state *conn_state,
+				struct link_config_limits *limits)
 {
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 	int forced_bpp;
@@ -1707,7 +1721,7 @@ int intel_dp_force_dsc_pipe_bpp(struct intel_dp *intel_dp)
 
 	forced_bpp = intel_dp->force_dsc_bpc * 3;
 
-	if (is_dsc_pipe_bpp_sufficient(i915, forced_bpp)) {
+	if (is_dsc_pipe_bpp_sufficient(i915, conn_state, limits, forced_bpp)) {
 		drm_dbg_kms(&i915->drm, "Input DSC BPC forced to %d\n", intel_dp->force_dsc_bpc);
 		return forced_bpp;
 	}
@@ -1729,16 +1743,16 @@ static int intel_dp_dsc_compute_pipe_bpp(struct intel_dp *intel_dp,
 	u16 output_bpp, dsc_max_compressed_bpp = 0;
 	int forced_bpp, pipe_bpp;
 
-	forced_bpp = intel_dp_force_dsc_pipe_bpp(intel_dp);
+	forced_bpp = intel_dp_force_dsc_pipe_bpp(intel_dp, conn_state, limits);
 
 	if (forced_bpp) {
 		pipe_bpp = forced_bpp;
 	} else {
 		pipe_bpp = intel_dp_dsc_compute_max_bpp(intel_dp, conn_state->max_requested_bpc);
 
-		if (!is_dsc_pipe_bpp_sufficient(i915, pipe_bpp)) {
+		if (!is_dsc_pipe_bpp_sufficient(i915, conn_state, limits, pipe_bpp)) {
 			drm_dbg_kms(&i915->drm,
-				    "Computed BPC less than min supported by source for DSC\n");
+				    "Computed BPC is not in DSC BPC limits\n");
 			return -EINVAL;
 		}
 	}
@@ -1780,7 +1794,7 @@ static int intel_edp_dsc_compute_pipe_bpp(struct intel_dp *intel_dp,
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 	int pipe_bpp, forced_bpp;
 
-	forced_bpp = intel_dp_force_dsc_pipe_bpp(intel_dp);
+	forced_bpp = intel_dp_force_dsc_pipe_bpp(intel_dp, conn_state, limits);
 
 	if (forced_bpp) {
 		pipe_bpp = forced_bpp;
@@ -1788,9 +1802,9 @@ static int intel_edp_dsc_compute_pipe_bpp(struct intel_dp *intel_dp,
 		/* For eDP use max bpp that can be supported with DSC. */
 		pipe_bpp = intel_dp_dsc_compute_max_bpp(intel_dp,
 							conn_state->max_requested_bpc);
-		if (!is_dsc_pipe_bpp_sufficient(i915, pipe_bpp)) {
+		if (!is_dsc_pipe_bpp_sufficient(i915, conn_state, limits, pipe_bpp)) {
 			drm_dbg_kms(&i915->drm,
-				    "Computed BPC less than min supported by source for DSC\n");
+				    "Computed BPC is not in DSC BPC limits\n");
 			return -EINVAL;
 		}
 	}