drm/i915/dp: Refactor FEC support check in intel_dp_supports_dsc

Forward Error Correction is required for DP if we are using DSC but
is optional for eDP.

Currently the helper intel_dp_supports_dsc checks if fec_enable is set for
DP or not. The helper is called after fec_enable is set in crtc_state.

Instead of this a better approach would be to:
first, call intel_dp_supports_dsc to check for DSC support
(along with FEC requirement for DP) and then set fec_enable for DP
(if not already set) in crtc_state.

To achieve this, remove the check for fec_enable in the helper and instead
check for FEC support for DP. With this change the helper
intel_dp_supports_dsc can be called earlier and return early if DSC is
not supported. The structure intel_dp is added to the helper to get the
FEC support for DP.

v2: Pass intel_dp to adjust_limits_for_dsc_hblank_expansion_quirk
instead of deriving it from connector. (Jani)

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241217093244.3938132-2-ankit.k.nautiyal@intel.com

3 files changed, 13 insertions, 8 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index fba3af338280..908b9887f89b 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -1627,13 +1627,15 @@ bool intel_dp_supports_fec(struct intel_dp *intel_dp,
 		drm_dp_sink_supports_fec(connector->dp.fec_capability);
 }
 
-bool intel_dp_supports_dsc(const struct intel_connector *connector,
+bool intel_dp_supports_dsc(struct intel_dp *intel_dp,
+			   const struct intel_connector *connector,
 			   const struct intel_crtc_state *crtc_state)
 {
 	if (!intel_dp_has_dsc(connector))
 		return false;
 
-	if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP) && !crtc_state->fec_enable)
+	if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP) &&
+	    !intel_dp_supports_fec(intel_dp, connector, crtc_state))
 		return false;
 
 	return intel_dsc_source_support(crtc_state);
@@ -2373,7 +2375,7 @@ int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
 		 intel_dp_supports_fec(intel_dp, connector, pipe_config) &&
 		 !intel_dp_is_uhbr(pipe_config));
 
-	if (!intel_dp_supports_dsc(connector, pipe_config))
+	if (!intel_dp_supports_dsc(intel_dp, connector, pipe_config))
 		return -EINVAL;
 
 	if (!intel_dp_dsc_supports_format(connector, pipe_config->output_format))
diff --git a/drivers/gpu/drm/i915/display/intel_dp.h b/drivers/gpu/drm/i915/display/intel_dp.h
index a1fd21c3b792..03dde9756bdc 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.h
+++ b/drivers/gpu/drm/i915/display/intel_dp.h
@@ -170,7 +170,8 @@ bool intel_dp_supports_fec(struct intel_dp *intel_dp,
 			   const struct intel_connector *connector,
 			   const struct intel_crtc_state *pipe_config);
 
-bool intel_dp_supports_dsc(const struct intel_connector *connector,
+bool intel_dp_supports_dsc(struct intel_dp *intel_dp,
+			   const struct intel_connector *connector,
 			   const struct intel_crtc_state *crtc_state);
 
 u32 intel_dp_dsc_nearest_valid_bpp(struct intel_display *display, u32 bpp, u32 pipe_bpp);
diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index 326ff20a5a49..4217350eefb0 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -519,7 +519,8 @@ hblank_expansion_quirk_needs_dsc(const struct intel_connector *connector,
 }
 
 static bool
-adjust_limits_for_dsc_hblank_expansion_quirk(const struct intel_connector *connector,
+adjust_limits_for_dsc_hblank_expansion_quirk(struct intel_dp *intel_dp,
+					     const struct intel_connector *connector,
 					     const struct intel_crtc_state *crtc_state,
 					     struct link_config_limits *limits,
 					     bool dsc)
@@ -532,7 +533,7 @@ adjust_limits_for_dsc_hblank_expansion_quirk(const struct intel_connector *conne
 		return true;
 
 	if (!dsc) {
-		if (intel_dp_supports_dsc(connector, crtc_state)) {
+		if (intel_dp_supports_dsc(intel_dp, connector, crtc_state)) {
 			drm_dbg_kms(display->drm,
 				    "[CRTC:%d:%s][CONNECTOR:%d:%s] DSC needed by hblank expansion quirk\n",
 				    crtc->base.base.id, crtc->base.name,
@@ -588,7 +589,8 @@ mst_stream_compute_config_limits(struct intel_dp *intel_dp,
 					    limits))
 		return false;
 
-	return adjust_limits_for_dsc_hblank_expansion_quirk(connector,
+	return adjust_limits_for_dsc_hblank_expansion_quirk(intel_dp,
+							    connector,
 							    crtc_state,
 							    limits,
 							    dsc);
@@ -651,7 +653,7 @@ static int mst_stream_compute_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_supports_dsc(connector, pipe_config))
+		if (!intel_dp_supports_dsc(intel_dp, connector, pipe_config))
 			return -EINVAL;
 
 		if (!mst_stream_compute_config_limits(intel_dp, connector,