drm/i915/dp: Replace intel_dp.dfp members with the new crtc_state sink_format

The decision to use DFP output format conversion capabilities should be
during compute_config phase.

This patch uses the members of intel_dp->dfp to only store the
format conversion capabilities of the DP device and uses the crtc_state
sink_format member, to program the protocol-converter for
colorspace/format conversion.

v2: Use sink_format to determine the color conversion config for the
pcon (Ville).

v3: Fix typo: missing 'break' in switch case (lkp kernel test robot).

v4: Add helper to check if DP supports YCBCR420.

v5: Simplify logic for computing output_format, based on the given
sink_format. (Ville).
Added scaler constraint for YCbCr420 output.

v6: Split the patch for Scaler constraint for Ycbcr420.

v7: Simplify the policy for selecting output_format:
Always try for RGB first, followed by YCBCR444, and finally by YCBCR420.

v8: Removed redundant comments, minor refactoring. (Ville)

v9: Added member for ycbcr420 passthrough cap, fixed minor issues. (Ville)
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230427125605.487769-3-ankit.k.nautiyal@intel.com

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

@@ -1775,6 +1775,7 @@ struct intel_dp {
 		int pcon_max_frl_bw;
 		u8 max_bpc;
 		bool ycbcr_444_to_420;
+		bool ycbcr420_passthrough;
 		bool rgb_to_ycbcr;
 	} dfp;
 

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

@@ -849,27 +849,88 @@ u8 intel_dp_dsc_get_slice_count(struct intel_dp *intel_dp,
 	return 0;
 }
 
+static bool source_can_output(struct intel_dp *intel_dp,
+			      enum intel_output_format format)
+{
+	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
+
+	switch (format) {
+	case INTEL_OUTPUT_FORMAT_RGB:
+		return true;
+
+	case INTEL_OUTPUT_FORMAT_YCBCR444:
+		/*
+		 * No YCbCr output support on gmch platforms.
+		 * Also, ILK doesn't seem capable of DP YCbCr output.
+		 * The displayed image is severly corrupted. SNB+ is fine.
+		 */
+		return !HAS_GMCH(i915) && !IS_IRONLAKE(i915);
+
+	case INTEL_OUTPUT_FORMAT_YCBCR420:
+		/* Platform < Gen 11 cannot output YCbCr420 format */
+		return DISPLAY_VER(i915) >= 11;
+
+	default:
+		MISSING_CASE(format);
+		return false;
+	}
+}
+
+static bool
+dfp_can_convert_from_rgb(struct intel_dp *intel_dp,
+			 enum intel_output_format sink_format)
+{
+	if (!drm_dp_is_branch(intel_dp->dpcd))
+		return false;
+
+	if (sink_format == INTEL_OUTPUT_FORMAT_YCBCR444)
+		return intel_dp->dfp.rgb_to_ycbcr;
+
+	if (sink_format == INTEL_OUTPUT_FORMAT_YCBCR420)
+		return intel_dp->dfp.rgb_to_ycbcr &&
+			intel_dp->dfp.ycbcr_444_to_420;
+
+	return false;
+}
+
+static bool
+dfp_can_convert_from_ycbcr444(struct intel_dp *intel_dp,
+			      enum intel_output_format sink_format)
+{
+	if (!drm_dp_is_branch(intel_dp->dpcd))
+		return false;
+
+	if (sink_format == INTEL_OUTPUT_FORMAT_YCBCR420)
+		return intel_dp->dfp.ycbcr_444_to_420;
+
+	return false;
+}
+
 static enum intel_output_format
 intel_dp_output_format(struct intel_connector *connector,
 		       enum intel_output_format sink_format)
 {
 	struct intel_dp *intel_dp = intel_attached_dp(connector);
+	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
+	enum intel_output_format output_format;
 
 	if (intel_dp->force_dsc_output_format)
 		return intel_dp->force_dsc_output_format;
 
-	if (!connector->base.ycbcr_420_allowed ||
-	    sink_format != INTEL_OUTPUT_FORMAT_YCBCR420)
-		return INTEL_OUTPUT_FORMAT_RGB;
+	if (sink_format == INTEL_OUTPUT_FORMAT_RGB ||
+	    dfp_can_convert_from_rgb(intel_dp, sink_format))
+		output_format = INTEL_OUTPUT_FORMAT_RGB;
 
-	if (intel_dp->dfp.rgb_to_ycbcr &&
-	    intel_dp->dfp.ycbcr_444_to_420)
-		return INTEL_OUTPUT_FORMAT_RGB;
+	else if (sink_format == INTEL_OUTPUT_FORMAT_YCBCR444 ||
+		 dfp_can_convert_from_ycbcr444(intel_dp, sink_format))
+		output_format = INTEL_OUTPUT_FORMAT_YCBCR444;
 
-	if (intel_dp->dfp.ycbcr_444_to_420)
-		return INTEL_OUTPUT_FORMAT_YCBCR444;
 	else
-		return INTEL_OUTPUT_FORMAT_YCBCR420;
+		output_format = INTEL_OUTPUT_FORMAT_YCBCR420;
+
+	drm_WARN_ON(&i915->drm, !source_can_output(intel_dp, output_format));
+
+	return output_format;
 }
 
 int intel_dp_min_bpp(enum intel_output_format output_format)
@@ -2829,6 +2890,8 @@ void intel_dp_configure_protocol_converter(struct intel_dp *intel_dp,
 					   const struct intel_crtc_state *crtc_state)
 {
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
+	bool ycbcr444_to_420 = false;
+	bool rgb_to_ycbcr = false;
 	u8 tmp;
 
 	if (intel_dp->dpcd[DP_DPCD_REV] < 0x13)
@@ -2845,8 +2908,24 @@ void intel_dp_configure_protocol_converter(struct intel_dp *intel_dp,
 		drm_dbg_kms(&i915->drm, "Failed to %s protocol converter HDMI mode\n",
 			    str_enable_disable(intel_dp->has_hdmi_sink));
 
-	tmp = crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR444 &&
-		intel_dp->dfp.ycbcr_444_to_420 ? DP_CONVERSION_TO_YCBCR420_ENABLE : 0;
+	if (crtc_state->sink_format == INTEL_OUTPUT_FORMAT_YCBCR420) {
+		switch (crtc_state->output_format) {
+		case INTEL_OUTPUT_FORMAT_YCBCR420:
+			break;
+		case INTEL_OUTPUT_FORMAT_YCBCR444:
+			ycbcr444_to_420 = true;
+			break;
+		case INTEL_OUTPUT_FORMAT_RGB:
+			rgb_to_ycbcr = true;
+			ycbcr444_to_420 = true;
+			break;
+		default:
+			MISSING_CASE(crtc_state->output_format);
+			break;
+		}
+	}
+
+	tmp = ycbcr444_to_420 ? DP_CONVERSION_TO_YCBCR420_ENABLE : 0;
 
 	if (drm_dp_dpcd_writeb(&intel_dp->aux,
 			       DP_PROTOCOL_CONVERTER_CONTROL_1, tmp) != 1)
@@ -2854,13 +2933,12 @@ void intel_dp_configure_protocol_converter(struct intel_dp *intel_dp,
 			    "Failed to %s protocol converter YCbCr 4:2:0 conversion mode\n",
 			    str_enable_disable(intel_dp->dfp.ycbcr_444_to_420));
 
-	tmp = intel_dp->dfp.rgb_to_ycbcr ?
-		DP_CONVERSION_BT709_RGB_YCBCR_ENABLE : 0;
+	tmp = rgb_to_ycbcr ? DP_CONVERSION_BT709_RGB_YCBCR_ENABLE : 0;
 
 	if (drm_dp_pcon_convert_rgb_to_ycbcr(&intel_dp->aux, tmp) < 0)
 		drm_dbg_kms(&i915->drm,
-			   "Failed to %s protocol converter RGB->YCbCr conversion mode\n",
-			   str_enable_disable(tmp));
+			    "Failed to %s protocol converter RGB->YCbCr conversion mode\n",
+			    str_enable_disable(tmp));
 }
 
 bool intel_dp_get_colorimetry_status(struct intel_dp *intel_dp)
@@ -4650,57 +4728,44 @@ intel_dp_update_dfp(struct intel_dp *intel_dp,
 	intel_dp_get_pcon_dsc_cap(intel_dp);
 }
 
+static bool
+intel_dp_can_ycbcr420(struct intel_dp *intel_dp)
+{
+	if (source_can_output(intel_dp, INTEL_OUTPUT_FORMAT_YCBCR420) &&
+	    (!drm_dp_is_branch(intel_dp->dpcd) || intel_dp->dfp.ycbcr420_passthrough))
+		return true;
+
+	if (source_can_output(intel_dp, INTEL_OUTPUT_FORMAT_RGB) &&
+	    dfp_can_convert_from_rgb(intel_dp, INTEL_OUTPUT_FORMAT_YCBCR420))
+		return true;
+
+	if (source_can_output(intel_dp, INTEL_OUTPUT_FORMAT_YCBCR444) &&
+	    dfp_can_convert_from_ycbcr444(intel_dp, INTEL_OUTPUT_FORMAT_YCBCR420))
+		return true;
+
+	return false;
+}
+
 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, rgb_to_ycbcr;
-
-	/* 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_IRONLAKE(i915))
-		return;
-
-	is_branch = drm_dp_is_branch(intel_dp->dpcd);
-	ycbcr_420_passthrough =
+	intel_dp->dfp.ycbcr420_passthrough =
 		drm_dp_downstream_420_passthrough(intel_dp->dpcd,
 						  intel_dp->downstream_ports);
 	/* on-board LSPCON always assumed to support 4:4:4->4:2:0 conversion */
-	ycbcr_444_to_420 =
+	intel_dp->dfp.ycbcr_444_to_420 =
 		dp_to_dig_port(intel_dp)->lspcon.active ||
 		drm_dp_downstream_444_to_420_conversion(intel_dp->dpcd,
 							intel_dp->downstream_ports);
-	rgb_to_ycbcr = drm_dp_downstream_rgb_to_ycbcr_conversion(intel_dp->dpcd,
-								 intel_dp->downstream_ports,
-								 DP_DS_HDMI_BT709_RGB_YCBCR_CONV);
-
-	if (DISPLAY_VER(i915) >= 11) {
-		/* Let PCON convert from RGB->YCbCr if possible */
-		if (is_branch && rgb_to_ycbcr && ycbcr_444_to_420) {
-			intel_dp->dfp.rgb_to_ycbcr = true;
-			intel_dp->dfp.ycbcr_444_to_420 = true;
-			connector->base.ycbcr_420_allowed = true;
-		} else {
-		/* 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;
+	intel_dp->dfp.rgb_to_ycbcr =
+		drm_dp_downstream_rgb_to_ycbcr_conversion(intel_dp->dpcd,
+							  intel_dp->downstream_ports,
+							  DP_DS_HDMI_BT709_RGB_YCBCR_CONV);
 
-			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;
-	}
+	connector->base.ycbcr_420_allowed = intel_dp_can_ycbcr420(intel_dp);
 
 	drm_dbg_kms(&i915->drm,
 		    "[CONNECTOR:%d:%s] RGB->YcbCr conversion? %s, YCbCr 4:2:0 allowed? %s, YCbCr 4:4:4->4:2:0 conversion? %s\n",