[PATCH v6 08/13] drm/amd/display: Validate DSC caps on MST endpoints

[<mikita.lipski@xxxxxxx>]

From: David Francis <David.Francis@xxxxxxx>

During MST mode enumeration, if a new dc_sink is created,
populate it with dsc caps as appropriate.

Use drm_dp_mst_dsc_aux_for_port to get the raw caps,
then parse them onto dc_sink with dc_dsc_parse_dsc_dpcd.

Reviewed-by: Wenjing Liu <Wenjing.Liu@xxxxxxx>
Signed-off-by: David Francis <David.Francis@xxxxxxx>
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |  3 ++
 .../display/amdgpu_dm/amdgpu_dm_mst_types.c   | 31 ++++++++++++++++++-
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
index f6e18d8a9936..c7f1e2f00fac 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
@@ -323,6 +323,9 @@ struct amdgpu_dm_connector {
 	struct drm_dp_mst_port *port;
 	struct amdgpu_dm_connector *mst_port;
 	struct amdgpu_encoder *mst_encoder;
+#ifdef CONFIG_DRM_AMD_DC_DSC_SUPPORT
+	struct drm_dp_aux *dsc_aux;
+#endif
 
 	/* TODO see if we can merge with ddc_bus or make a dm_connector */
 	struct amdgpu_i2c_adapter *i2c;
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
index 1a17ea1b42e0..804a00082bee 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
@@ -25,6 +25,7 @@
 
 #include <linux/version.h>
 #include <drm/drm_atomic_helper.h>
+#include <drm/drm_dp_mst_helper.h>
 #include "dm_services.h"
 #include "amdgpu.h"
 #include "amdgpu_dm.h"
@@ -188,6 +189,28 @@ static const struct drm_connector_funcs dm_dp_mst_connector_funcs = {
 	.early_unregister = amdgpu_dm_mst_connector_early_unregister,
 };
 
+#ifdef CONFIG_DRM_AMD_DC_DSC_SUPPORT
+static bool validate_dsc_caps_on_connector(struct amdgpu_dm_connector *aconnector)
+{
+	struct dc_sink *dc_sink = aconnector->dc_sink;
+	struct drm_dp_mst_port *port = aconnector->port;
+	u8 dsc_caps[16] = { 0 };
+
+	aconnector->dsc_aux = drm_dp_mst_dsc_aux_for_port(port);
+
+	if (!aconnector->dsc_aux)
+		return false;
+
+	if (drm_dp_dpcd_read(aconnector->dsc_aux, DP_DSC_SUPPORT, dsc_caps, 16) < 0)
+		return false;
+
+	if (!dc_dsc_parse_dsc_dpcd(dsc_caps, NULL, &dc_sink->sink_dsc_caps.dsc_dec_caps))
+		return false;
+
+	return true;
+}
+#endif
+
 static int dm_dp_mst_get_modes(struct drm_connector *connector)
 {
 	struct amdgpu_dm_connector *aconnector = to_amdgpu_dm_connector(connector);
@@ -230,10 +253,16 @@ static int dm_dp_mst_get_modes(struct drm_connector *connector)
 		/* dc_link_add_remote_sink returns a new reference */
 		aconnector->dc_sink = dc_sink;
 
-		if (aconnector->dc_sink)
+		if (aconnector->dc_sink) {
 			amdgpu_dm_update_freesync_caps(
 					connector, aconnector->edid);
 
+#ifdef CONFIG_DRM_AMD_DC_DSC_SUPPORT
+			if (!validate_dsc_caps_on_connector(aconnector))
+				memset(&aconnector->dc_sink->sink_dsc_caps,
+				       0, sizeof(aconnector->dc_sink->sink_dsc_caps));
+#endif
+		}
 	}
 
 	drm_connector_update_edid_property(
-- 
2.17.1

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