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@intel.com --- 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 */