[PATCH v3 1/2] drm/i915/display: Cache DP colorimetry support per-connector

[Gil Dekel <gildekel@google.com>]

Query and cache colorimetry format support on a per-connector basis
instead of checking the root port's DPCD capabilities directly.

Introduce intel_dp_get_colorimetry_status_aux() to query colorimetry support
over a given DP AUX channel. For SST, cache this during intel_dp_detect().
For MST downstream ports, cache it using the port's sideband AUX
in mst_connector_detect_ctx().

This prepares the display driver to correctly identify colorimetry/VSC SDP
support on downstream MST sinks, where checking the root port's capabilities
incorrectly returns false.

Assisted-by: jetski:gemini-2.5-pro
Signed-off-by: Gil Dekel <gildekel@google.com>
---
 .../gpu/drm/i915/display/intel_display_types.h |  1 +
 drivers/gpu/drm/i915/display/intel_dp.c        | 18 ++++++++++++++----
 drivers/gpu/drm/i915/display/intel_dp.h        |  2 ++
 drivers/gpu/drm/i915/display/intel_dp_mst.c    | 13 +++++++++++--
 4 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index c048da7d6fea..428d55f9682f 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -564,6 +564,7 @@ struct intel_connector {
 		u8 dsc_hblank_expansion_quirk:1;
 		u8 dsc_throughput_quirk:1;
 		u8 dsc_decompression_enabled:1;
+		u8 colorimetry_support:1;
 
 		struct {
 			struct {
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 6e3fa6662cbe..1de26c4c867f 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -3161,9 +3161,9 @@ static void intel_dp_compute_vsc_sdp(struct intel_dp *intel_dp,
 				     struct intel_crtc_state *crtc_state,
 				     const struct drm_connector_state *conn_state)
 {
+	struct intel_connector *connector = to_intel_connector(conn_state->connector);
 	struct drm_dp_vsc_sdp *vsc;
-
-	if ((!intel_dp->colorimetry_support ||
+	if ((!connector->dp.colorimetry_support ||
 	     !intel_dp_needs_vsc_sdp(crtc_state, conn_state)) &&
 	    !crtc_state->has_psr)
 		return;
@@ -4438,16 +4438,21 @@ void intel_dp_configure_protocol_converter(struct intel_dp *intel_dp,
 			    str_enable_disable(tmp));
 }
 
-static bool intel_dp_get_colorimetry_status(struct intel_dp *intel_dp)
+bool intel_dp_get_colorimetry_status_aux(struct drm_dp_aux *aux)
 {
 	u8 dprx = 0;
 
-	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_DPRX_FEATURE_ENUMERATION_LIST,
+	if (drm_dp_dpcd_readb(aux, DP_DPRX_FEATURE_ENUMERATION_LIST,
 			      &dprx) != 1)
 		return false;
 	return dprx & DP_VSC_SDP_EXT_FOR_COLORIMETRY_SUPPORTED;
 }
 
+static bool intel_dp_get_colorimetry_status(struct intel_dp *intel_dp)
+{
+	return intel_dp_get_colorimetry_status_aux(&intel_dp->aux);
+}
+
 static int intel_dp_read_dsc_dpcd(struct drm_dp_aux *aux,
 				  u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE])
 {
@@ -6374,6 +6379,11 @@ intel_dp_detect(struct drm_connector *_connector,
 						 status,
 						 intel_dp->dpcd,
 						 intel_dp->downstream_ports);
+	if (status == connector_status_connected)
+		connector->dp.colorimetry_support = intel_dp->colorimetry_support;
+	else
+		connector->dp.colorimetry_support = false;
+
 out_vdd_off:
 	intel_pps_vdd_off(intel_dp);
 
diff --git a/drivers/gpu/drm/i915/display/intel_dp.h b/drivers/gpu/drm/i915/display/intel_dp.h
index 02b691df6755..26b3a0eb354e 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.h
+++ b/drivers/gpu/drm/i915/display/intel_dp.h
@@ -12,6 +12,7 @@ enum intel_output_format;
 enum pipe;
 enum port;
 struct drm_connector_state;
+struct drm_dp_aux;
 struct drm_dp_desc;
 struct drm_dp_vsc_sdp;
 struct drm_encoder;
@@ -78,6 +79,7 @@ int intel_dp_compute_config(struct intel_atomic_state *state,
 bool intel_dp_needs_8b10b_fec(const struct intel_crtc_state *crtc_state,
 			      bool dsc_enabled_on_crtc);
 void intel_dp_dsc_reset_config(struct intel_crtc_state *crtc_state);
+bool intel_dp_get_colorimetry_status_aux(struct drm_dp_aux *aux);
 int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
 				struct intel_crtc_state *pipe_config,
 				struct drm_connector_state *conn_state,
diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index ecc90e8faee1..5b76d12bb00f 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -1627,6 +1627,7 @@ mst_connector_detect_ctx(struct drm_connector *_connector,
 	struct intel_connector *connector = to_intel_connector(_connector);
 	struct intel_display *display = to_intel_display(connector);
 	struct intel_dp *intel_dp = connector->mst.dp;
+	int status;
 
 	if (!intel_display_device_enabled(display))
 		return connector_status_disconnected;
@@ -1639,8 +1640,16 @@ mst_connector_detect_ctx(struct drm_connector *_connector,
 
 	intel_dp_flush_connector_commits(connector);
 
-	return drm_dp_mst_detect_port(&connector->base, ctx, &intel_dp->mst.mgr,
-				      connector->mst.port);
+	status = drm_dp_mst_detect_port(&connector->base, ctx, &intel_dp->mst.mgr,
+					connector->mst.port);
+
+	if (status == connector_status_connected)
+		connector->dp.colorimetry_support =
+			intel_dp_get_colorimetry_status_aux(&connector->mst.port->aux);
+	else
+		connector->dp.colorimetry_support = false;
+
+	return status;
 }
 
 static const struct drm_connector_helper_funcs mst_connector_helper_funcs = {
-- 
Gil Dekel, Software Engineer, Google / ChromeOS Display and Graphics