[PATCH v4 15/16] drm/i915: Let PCON convert from RGB to YUV if it can

[Ankit Nautiyal]

If PCON has capability to convert RGB->YUV colorspace and also
to 444->420 downsampling then for any YUV420 only mode, we can
let the PCON do all the conversion.

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
---
 .../drm/i915/display/intel_display_types.h    |  1 +
 drivers/gpu/drm/i915/display/intel_dp.c       | 37 +++++++++++++------
 2 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index b41de41759a0..4150108bdc6d 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1460,6 +1460,7 @@ struct intel_dp {
 		int pcon_max_frl_bw, sink_max_frl_bw;
 		u8 max_bpc;
 		bool ycbcr_444_to_420;
+		bool rgb_to_ycbcr;
 	} dfp;
 
 	/* Display stream compression testing */
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 30c76ba63232..b3f1190d8150 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -651,6 +651,10 @@ intel_dp_output_format(struct drm_connector *connector,
 	    !drm_mode_is_420_only(info, mode))
 		return INTEL_OUTPUT_FORMAT_RGB;
 
+	if (intel_dp->dfp.rgb_to_ycbcr &&
+	    intel_dp->dfp.ycbcr_444_to_420)
+		return INTEL_OUTPUT_FORMAT_RGB;
+
 	if (intel_dp->dfp.ycbcr_444_to_420)
 		return INTEL_OUTPUT_FORMAT_YCBCR444;
 	else
@@ -4365,13 +4369,12 @@ void intel_dp_configure_protocol_converter(struct intel_dp *intel_dp)
 			    "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)
+	tmp = intel_dp->dfp.rgb_to_ycbcr ?
+		DP_CONVERSION_BT601_RGB_YCBCR_ENABLE : 0;
+	if (drm_dp_pcon_convert_rgb_to_ycbcr(&intel_dp->aux, tmp) <= 0)
 		drm_dbg_kms(&i915->drm,
-			    "Failed to set protocol converter YCbCr 4:2:2 conversion mode to %s\n",
-			    enableddisabled(false));
+			    "Failed to set protocol converter RGB->YCbCr conversion mode to %s\n",
+			    enableddisabled(intel_dp->dfp.rgb_to_ycbcr));
 }
 
 static void intel_enable_dp(struct intel_atomic_state *state,
@@ -6897,7 +6900,7 @@ 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;
+	bool is_branch, ycbcr_420_passthrough, ycbcr_444_to_420, rgb_to_ycbcr;
 
 	/* No YCbCr output support on gmch platforms */
 	if (HAS_GMCH(i915))
@@ -6919,14 +6922,23 @@ intel_dp_update_420(struct intel_dp *intel_dp)
 		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);
 
 	if (INTEL_GEN(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.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;
+			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;
@@ -6935,8 +6947,9 @@ intel_dp_update_420(struct intel_dp *intel_dp)
 	}
 
 	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:%d:%s] RGB->YcbCr conversion? %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(intel_dp->dfp.rgb_to_ycbcr),
 		    yesno(connector->base.ycbcr_420_allowed),
 		    yesno(intel_dp->dfp.ycbcr_444_to_420));
 }
-- 
2.17.1