drm/i915/dp_mst: Use the correct connector while computing the link BPP limit on MST

Atm, on an MST link in DSC mode
intel_dp_compute_config_link_bpp_limits() calculates the maximum link
bpp limit using the MST root connector's DSC capabilities. That's not
correct in general: the decompression could be performed by a branch
device downstream of the root branch device or the sink itself.

Fix the above by passing to intel_dp_compute_config_link_bpp_limits()
the actual connector being modeset, containing the correct DSC
capabilities.

Cc: Ankit Nautiyal <[email protected]>
Fixes: 1c5b72d ("drm/i915/dp: Set the DSC link limits in intel_dp_compute_config_link_bpp_limits")
Reviewed-by: Ankit Nautiyal <[email protected]>
Reviewed-by: Luca Coelho <[email protected]>
Signed-off-by: Imre Deak <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
(cherry picked from commit 266e2fc)
Signed-off-by: Joonas Lahtinen <[email protected]>

Author: ideak

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

@@ -2524,6 +2524,7 @@ intel_dp_dsc_compute_pipe_bpp_limits(struct intel_dp *intel_dp,
 
 bool
 intel_dp_compute_config_limits(struct intel_dp *intel_dp,
+			       struct intel_connector *connector,
 			       struct intel_crtc_state *crtc_state,
 			       bool respect_downstream_limits,
 			       bool dsc,
@@ -2577,7 +2578,7 @@ intel_dp_compute_config_limits(struct intel_dp *intel_dp,
 	intel_dp_test_compute_config(intel_dp, crtc_state, limits);
 
 	return intel_dp_compute_config_link_bpp_limits(intel_dp,
-						       intel_dp->attached_connector,
+						       connector,
 						       crtc_state,
 						       dsc,
 						       limits);
@@ -2638,7 +2639,7 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
 	joiner_needs_dsc = intel_dp_joiner_needs_dsc(display, num_joined_pipes);
 
 	dsc_needed = joiner_needs_dsc || intel_dp->force_dsc_en ||
-		     !intel_dp_compute_config_limits(intel_dp, pipe_config,
+		     !intel_dp_compute_config_limits(intel_dp, connector, pipe_config,
 						     respect_downstream_limits,
 						     false,
 						     &limits);
@@ -2672,7 +2673,7 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
 			    str_yes_no(ret), str_yes_no(joiner_needs_dsc),
 			    str_yes_no(intel_dp->force_dsc_en));
 
-		if (!intel_dp_compute_config_limits(intel_dp, pipe_config,
+		if (!intel_dp_compute_config_limits(intel_dp, connector, pipe_config,
 						    respect_downstream_limits,
 						    true,
 						    &limits))

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

@@ -194,6 +194,7 @@ void intel_dp_wait_source_oui(struct intel_dp *intel_dp);
 int intel_dp_output_bpp(enum intel_output_format output_format, int bpp);
 
 bool intel_dp_compute_config_limits(struct intel_dp *intel_dp,
+				    struct intel_connector *connector,
 				    struct intel_crtc_state *crtc_state,
 				    bool respect_downstream_limits,
 				    bool dsc,

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

@@ -599,12 +599,13 @@ adjust_limits_for_dsc_hblank_expansion_quirk(struct intel_dp *intel_dp,
 
 static bool
 mst_stream_compute_config_limits(struct intel_dp *intel_dp,
-				 const struct intel_connector *connector,
+				 struct intel_connector *connector,
 				 struct intel_crtc_state *crtc_state,
 				 bool dsc,
 				 struct link_config_limits *limits)
 {
-	if (!intel_dp_compute_config_limits(intel_dp, crtc_state, false, dsc,
+	if (!intel_dp_compute_config_limits(intel_dp, connector,
+					    crtc_state, false, dsc,
 					    limits))
 		return false;