When a DP downstream uses a DP to HDMI active converter, the active
converter needs to support YCbCr420 Pass-through to enable DP YCbCr 4:2:0
outputs.
Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@xxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_dp.c | 26 +++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index f4dede6253f8..824ed8096426 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -2298,6 +2298,22 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
return 0;
}
+static bool
+intel_dp_downstream_is_hdmi_detailed_cap_info(struct intel_dp *intel_dp)
+{
+ int type = intel_dp->downstream_ports[0] & DP_DS_PORT_TYPE_MASK;
+ bool detailed_cap_info = intel_dp->dpcd[DP_DOWNSTREAMPORT_PRESENT] &
+ DP_DETAILED_CAP_INFO_AVAILABLE;
+
+ return type == DP_DS_PORT_TYPE_HDMI && detailed_cap_info;
+}
+
+static bool
+intel_dp_downstream_supports_ycbcr_420_passthru(struct intel_dp *intel_dp)
+{
+ return intel_dp->downstream_ports[3] & DP_DS_YCBCR420_PASSTHRU_SUPPORT;
+}
+
static int
intel_dp_ycbcr420_config(struct intel_dp *intel_dp,
struct drm_connector *connector,
@@ -2314,6 +2330,16 @@ intel_dp_ycbcr420_config(struct intel_dp *intel_dp,
!connector->ycbcr_420_allowed)
return 0;
+ /*
+ * When a DP downstream uses a DP to HDMI active converter,
+ * the active converter needs to support YCbCr420 Pass-through.
+ */
+ if (drm_dp_is_branch(intel_dp->dpcd)) {
+ if (intel_dp_downstream_is_hdmi_detailed_cap_info(intel_dp) &&
+ !intel_dp_downstream_supports_ycbcr_420_passthru(intel_dp))
+ return 0;
+ }
+
crtc_state->output_format = INTEL_OUTPUT_FORMAT_YCBCR420;
/* YCBCR 420 output conversion needs a scaler */
--
2.24.1
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