drm/i915: Do YCbCr 444->420 conversion via DP protocol converters

For platforms that can't do native 4:2:0 outout we may still be
able to do it by getting the DP->HDMI protocol converter to
perform the 4:4:4->4:2:0 downsamling for us. In this case we
have to configure our hardware to output YCbCr 4:4:4, which we've
already hooked up so all we need to do is flip the switch.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200904115354.25336-19-ville.syrjala@linux.intel.comReviewed-by: Lyude Paul <lyude@redhat.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/display/intel_display_types.h

@@ -1386,6 +1386,7 @@ struct intel_dp {
 		int min_tmds_clock, max_tmds_clock;
 		int max_dotclock;
 		u8 max_bpc;
+		bool ycbcr_444_to_420;
 	} dfp;
 
 	/* Display stream compression testing */

drivers/gpu/drm/i915/display/intel_dp.c

@@ -1980,7 +1980,9 @@ static bool intel_dp_supports_dsc(struct intel_dp *intel_dp,
 static bool intel_dp_hdmi_ycbcr420(struct intel_dp *intel_dp,
 				   const struct intel_crtc_state *crtc_state)
 {
-	return crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR420;
+	return crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR420 ||
+		(crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR444 &&
+		 intel_dp->dfp.ycbcr_444_to_420);
 }
 
 static int intel_dp_hdmi_tmds_clock(struct intel_dp *intel_dp,
@@ -2014,9 +2016,10 @@ static bool intel_dp_hdmi_deep_color_possible(struct intel_dp *intel_dp,
 					      const struct intel_crtc_state *crtc_state,
 					      int bpc)
 {
-	bool has_hdmi_sink = intel_dp->has_hdmi_sink;
 
-	return intel_hdmi_deep_color_possible(crtc_state, bpc, has_hdmi_sink) &&
+	return intel_hdmi_deep_color_possible(crtc_state, bpc,
+					      intel_dp->has_hdmi_sink,
+					      intel_dp_hdmi_ycbcr420(intel_dp, crtc_state)) &&
 		intel_dp_hdmi_tmds_clock_valid(intel_dp, crtc_state, bpc);
 }
 
@@ -2436,11 +2439,17 @@ intel_dp_ycbcr420_config(struct intel_dp *intel_dp,
 	const struct drm_display_mode *adjusted_mode =
 		&crtc_state->hw.adjusted_mode;
 
-	if (!drm_mode_is_420_only(info, adjusted_mode) ||
-	    !intel_dp_get_colorimetry_status(intel_dp) ||
-	    !connector->ycbcr_420_allowed)
+	if (!connector->ycbcr_420_allowed)
 		return 0;
 
+	if (!drm_mode_is_420_only(info, adjusted_mode))
+		return 0;
+
+	if (intel_dp->dfp.ycbcr_444_to_420) {
+		crtc_state->output_format = INTEL_OUTPUT_FORMAT_YCBCR444;
+		return 0;
+	}
+
 	crtc_state->output_format = INTEL_OUTPUT_FORMAT_YCBCR420;
 
 	return intel_pch_panel_fitting(crtc_state, conn_state);
@@ -3858,11 +3867,26 @@ void intel_dp_configure_protocol_converter(struct intel_dp *intel_dp)
 		DP_HDMI_DVI_OUTPUT_CONFIG : 0;
 
 	if (drm_dp_dpcd_writeb(&intel_dp->aux,
-			       DP_PROTOCOL_CONVERTER_CONTROL_0, tmp) <= 0)
+			       DP_PROTOCOL_CONVERTER_CONTROL_0, tmp) != 1)
 		drm_dbg_kms(&i915->drm, "Failed to set protocol converter HDMI mode to %s\n",
 			    enableddisabled(intel_dp->has_hdmi_sink));
 
-	/* TODO: configure YCbCr 4:2:2/4:2:0 conversion */
+	tmp = intel_dp->dfp.ycbcr_444_to_420 ?
+		DP_CONVERSION_TO_YCBCR420_ENABLE : 0;
+
+	if (drm_dp_dpcd_writeb(&intel_dp->aux,
+			       DP_PROTOCOL_CONVERTER_CONTROL_1, tmp) != 1)
+		drm_dbg_kms(&i915->drm,
+			    "Failed to set protocol converter YCbCr 4:2:0 conversion mode to %s\n",
+			    enableddisabled(intel_dp->dfp.ycbcr_444_to_420));
+
+	tmp = 0;
+
+	if (drm_dp_dpcd_writeb(&intel_dp->aux,
+			       DP_PROTOCOL_CONVERTER_CONTROL_2, tmp) <= 0)
+		drm_dbg_kms(&i915->drm,
+			    "Failed to set protocol converter YCbCr 4:2:2 conversion mode to %s\n",
+			    enableddisabled(false));
 }
 
 static void intel_enable_dp(struct intel_atomic_state *state,
@@ -6142,15 +6166,11 @@ intel_dp_get_edid(struct intel_dp *intel_dp)
 }
 
 static void
-intel_dp_set_edid(struct intel_dp *intel_dp)
+intel_dp_update_dfp(struct intel_dp *intel_dp,
+		    const struct edid *edid)
 {
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 	struct intel_connector *connector = intel_dp->attached_connector;
-	struct edid *edid;
-
-	intel_dp_unset_edid(intel_dp);
-	edid = intel_dp_get_edid(intel_dp);
-	connector->detect_edid = edid;
 
 	intel_dp->dfp.max_bpc =
 		drm_dp_downstream_max_bpc(intel_dp->dpcd,
@@ -6176,6 +6196,67 @@ intel_dp_set_edid(struct intel_dp *intel_dp)
 		    intel_dp->dfp.max_dotclock,
 		    intel_dp->dfp.min_tmds_clock,
 		    intel_dp->dfp.max_tmds_clock);
+}
+
+static void
+intel_dp_update_420(struct intel_dp *intel_dp)
+{
+	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
+	struct intel_connector *connector = intel_dp->attached_connector;
+	bool is_branch, ycbcr_420_passthrough, ycbcr_444_to_420;
+
+	/* No YCbCr output support on gmch platforms */
+	if (HAS_GMCH(i915))
+		return;
+
+	/*
+	 * ILK doesn't seem capable of DP YCbCr output. The
+	 * displayed image is severly corrupted. SNB+ is fine.
+	 */
+	if (IS_GEN(i915, 5))
+		return;
+
+	is_branch = drm_dp_is_branch(intel_dp->dpcd);
+	ycbcr_420_passthrough =
+		drm_dp_downstream_420_passthrough(intel_dp->dpcd,
+						  intel_dp->downstream_ports);
+	ycbcr_444_to_420 =
+		drm_dp_downstream_444_to_420_conversion(intel_dp->dpcd,
+							intel_dp->downstream_ports);
+
+	if (INTEL_GEN(i915) >= 11) {
+		/* Prefer 4:2:0 passthrough over 4:4:4->4:2:0 conversion */
+		intel_dp->dfp.ycbcr_444_to_420 =
+			ycbcr_444_to_420 && !ycbcr_420_passthrough;
+
+		connector->base.ycbcr_420_allowed =
+			!is_branch || ycbcr_444_to_420 || ycbcr_420_passthrough;
+	} else {
+		/* 4:4:4->4:2:0 conversion is the only way */
+		intel_dp->dfp.ycbcr_444_to_420 = ycbcr_444_to_420;
+
+		connector->base.ycbcr_420_allowed = ycbcr_444_to_420;
+	}
+
+	drm_dbg_kms(&i915->drm,
+		    "[CONNECTOR:%d:%s] YCbCr 4:2:0 allowed? %s, YCbCr 4:4:4->4:2:0 conversion? %s\n",
+		    connector->base.base.id, connector->base.name,
+		    yesno(connector->base.ycbcr_420_allowed),
+		    yesno(intel_dp->dfp.ycbcr_444_to_420));
+}
+
+static void
+intel_dp_set_edid(struct intel_dp *intel_dp)
+{
+	struct intel_connector *connector = intel_dp->attached_connector;
+	struct edid *edid;
+
+	intel_dp_unset_edid(intel_dp);
+	edid = intel_dp_get_edid(intel_dp);
+	connector->detect_edid = edid;
+
+	intel_dp_update_dfp(intel_dp, edid);
+	intel_dp_update_420(intel_dp);
 
 	if (edid && edid->input & DRM_EDID_INPUT_DIGITAL) {
 		intel_dp->has_hdmi_sink = drm_detect_hdmi_monitor(edid);
@@ -6189,11 +6270,11 @@ intel_dp_set_edid(struct intel_dp *intel_dp)
 static void
 intel_dp_unset_edid(struct intel_dp *intel_dp)
 {
-	struct intel_connector *intel_connector = intel_dp->attached_connector;
+	struct intel_connector *connector = intel_dp->attached_connector;
 
 	drm_dp_cec_unset_edid(&intel_dp->aux);
-	kfree(intel_connector->detect_edid);
-	intel_connector->detect_edid = NULL;
+	kfree(connector->detect_edid);
+	connector->detect_edid = NULL;
 
 	intel_dp->has_hdmi_sink = false;
 	intel_dp->has_audio = false;
@@ -6203,6 +6284,9 @@ intel_dp_unset_edid(struct intel_dp *intel_dp)
 	intel_dp->dfp.max_dotclock = 0;
 	intel_dp->dfp.min_tmds_clock = 0;
 	intel_dp->dfp.max_tmds_clock = 0;
+
+	intel_dp->dfp.ycbcr_444_to_420 = false;
+	connector->base.ycbcr_420_allowed = false;
 }
 
 static int
@@ -7729,9 +7813,6 @@ intel_dp_init_connector(struct intel_digital_port *dig_port,
 		connector->interlace_allowed = true;
 	connector->doublescan_allowed = 0;
 
-	if (INTEL_GEN(dev_priv) >= 11)
-		connector->ycbcr_420_allowed = true;
-
 	intel_connector->polled = DRM_CONNECTOR_POLL_HPD;
 
 	intel_dp_aux_init(intel_dp);

drivers/gpu/drm/i915/display/intel_hdmi.c

@@ -2278,7 +2278,7 @@ intel_hdmi_mode_valid(struct drm_connector *connector,
 }
 
 bool intel_hdmi_deep_color_possible(const struct intel_crtc_state *crtc_state,
-				    int bpc, bool has_hdmi_sink)
+				    int bpc, bool has_hdmi_sink, bool ycbcr420_output)
 {
 	struct drm_atomic_state *state = crtc_state->uapi.state;
 	struct drm_connector_state *connector_state;
@@ -2297,7 +2297,7 @@ bool intel_hdmi_deep_color_possible(const struct intel_crtc_state *crtc_state,
 		if (connector_state->crtc != crtc_state->uapi.crtc)
 			continue;
 
-		if (crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR420) {
+		if (ycbcr420_output) {
 			const struct drm_hdmi_info *hdmi = &info->hdmi;
 
 			if (bpc == 12 && !(hdmi->y420_dc_modes &
@@ -2348,7 +2348,9 @@ static bool hdmi_deep_color_possible(const struct intel_crtc_state *crtc_state,
 		return false;
 
 	return intel_hdmi_deep_color_possible(crtc_state, bpc,
-					      crtc_state->has_hdmi_sink);
+					      crtc_state->has_hdmi_sink,
+					      crtc_state->output_format ==
+					      INTEL_OUTPUT_FORMAT_YCBCR420);
 }
 
 static int

drivers/gpu/drm/i915/display/intel_hdmi.h

@@ -48,7 +48,7 @@ void intel_read_infoframe(struct intel_encoder *encoder,
 			  union hdmi_infoframe *frame);
 bool intel_hdmi_limited_color_range(const struct intel_crtc_state *crtc_state,
 				    const struct drm_connector_state *conn_state);
-bool intel_hdmi_deep_color_possible(const struct intel_crtc_state *crtc_state,
-				    int bpc, bool has_hdmi_sink);
+bool intel_hdmi_deep_color_possible(const struct intel_crtc_state *crtc_state, int bpc,
+				    bool has_hdmi_sink, bool ycbcr420_output);
 
 #endif /* __INTEL_HDMI_H__ */