drm/amd/display: Prune Invalid Modes For HDMI Output

[Why]
1. HDMI does not have 6 bpc support. Having 6 bpc pass validation
does not comply with spec.
2. Validate 420 only for native HDMI, but not apply to pcon use
case.
3. Current mode validation log is not readable.

[how]
1. Cap 8 bpc for dp-hdmi converter.
2. Validate yuv420 for pcon use case as well,
   if rgb/yuv444 8bpc cannot fit into pcon bw limitation of
   the link from the converter to HDMI sink.
3. Add readable pixel_format and color_depth into debug log.

Reviewed-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Fangzhi Zuo <Jerry.Zuo@amd.com>
Signed-off-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -7323,10 +7323,15 @@ create_validate_stream_for_sink(struct amdgpu_dm_connector *aconnector,
 	const struct drm_connector_state *drm_state = dm_state ? &dm_state->base : NULL;
 	int requested_bpc = drm_state ? drm_state->max_requested_bpc : 8;
 	enum dc_status dc_result = DC_OK;
+	uint8_t bpc_limit = 6;
 
 	if (!dm_state)
 		return NULL;
 
+	if (aconnector->dc_link->connector_signal == SIGNAL_TYPE_HDMI_TYPE_A ||
+	    aconnector->dc_link->dpcd_caps.dongle_type == DISPLAY_DONGLE_DP_HDMI_CONVERTER)
+		bpc_limit = 8;
+
 	do {
 		stream = create_stream_for_sink(connector, drm_mode,
 						dm_state, old_stream,
@@ -7347,22 +7352,26 @@ create_validate_stream_for_sink(struct amdgpu_dm_connector *aconnector,
 			dc_result = dm_validate_stream_and_context(adev->dm.dc, stream);
 
 		if (dc_result != DC_OK) {
-			DRM_DEBUG_KMS("Mode %dx%d (clk %d) failed DC validation with error %d (%s)\n",
+			DRM_DEBUG_KMS("Mode %dx%d (clk %d) pixel_encoding:%s color_depth:%s failed validation -- %s\n",
 				      drm_mode->hdisplay,
 				      drm_mode->vdisplay,
 				      drm_mode->clock,
-				      dc_result,
+				      dc_pixel_encoding_to_str(stream->timing.pixel_encoding),
+				      dc_color_depth_to_str(stream->timing.display_color_depth),
 				      dc_status_to_str(dc_result));
 
 			dc_stream_release(stream);
 			stream = NULL;
 			requested_bpc -= 2; /* lower bpc to retry validation */
 		}
 
-	} while (stream == NULL && requested_bpc >= 6);
+	} while (stream == NULL && requested_bpc >= bpc_limit);
 
-	if (dc_result == DC_FAIL_ENC_VALIDATE && !aconnector->force_yuv420_output) {
-		DRM_DEBUG_KMS("Retry forcing YCbCr420 encoding\n");
+	if ((dc_result == DC_FAIL_ENC_VALIDATE ||
+	     dc_result == DC_EXCEED_DONGLE_CAP) &&
+	     !aconnector->force_yuv420_output) {
+		DRM_DEBUG_KMS("%s:%d Retry forcing yuv420 encoding\n",
+				     __func__, __LINE__);
 
 		aconnector->force_yuv420_output = true;
 		stream = create_validate_stream_for_sink(aconnector, drm_mode,

drivers/gpu/drm/amd/display/dc/core/dc_debug.c

@@ -392,3 +392,43 @@ char *dc_status_to_str(enum dc_status status)
 
 	return "Unexpected status error";
 }
+
+char *dc_pixel_encoding_to_str(enum dc_pixel_encoding pixel_encoding)
+{
+	switch (pixel_encoding) {
+	case PIXEL_ENCODING_RGB:
+		return "RGB";
+	case PIXEL_ENCODING_YCBCR422:
+		return "YUV422";
+	case PIXEL_ENCODING_YCBCR444:
+		return "YUV444";
+	case PIXEL_ENCODING_YCBCR420:
+		return "YUV420";
+	default:
+		return "Unknown";
+	}
+}
+
+char *dc_color_depth_to_str(enum dc_color_depth color_depth)
+{
+	switch (color_depth) {
+	case COLOR_DEPTH_666:
+		return "6-bpc";
+	case COLOR_DEPTH_888:
+		return "8-bpc";
+	case COLOR_DEPTH_101010:
+		return "10-bpc";
+	case COLOR_DEPTH_121212:
+		return "12-bpc";
+	case COLOR_DEPTH_141414:
+		return "14-bpc";
+	case COLOR_DEPTH_161616:
+		return "16-bpc";
+	case COLOR_DEPTH_999:
+		return "9-bpc";
+	case COLOR_DEPTH_111111:
+		return "11-bpc";
+	default:
+		return "Unknown";
+	}
+}

drivers/gpu/drm/amd/display/dc/core/dc_stream.c

@@ -812,12 +812,12 @@ void dc_stream_log(const struct dc *dc, const struct dc_stream_state *stream)
 			stream->dst.height,
 			stream->output_color_space);
 	DC_LOG_DC(
-			"\tpix_clk_khz: %d, h_total: %d, v_total: %d, pixelencoder:%d, displaycolorDepth:%d\n",
+			"\tpix_clk_khz: %d, h_total: %d, v_total: %d, pixel_encoding:%s, color_depth:%s\n",
 			stream->timing.pix_clk_100hz / 10,
 			stream->timing.h_total,
 			stream->timing.v_total,
-			stream->timing.pixel_encoding,
-			stream->timing.display_color_depth);
+			dc_pixel_encoding_to_str(stream->timing.pixel_encoding),
+			dc_color_depth_to_str(stream->timing.display_color_depth));
 	DC_LOG_DC(
 			"\tlink: %d\n",
 			stream->link->link_index);

drivers/gpu/drm/amd/display/dc/inc/core_status.h

@@ -60,5 +60,7 @@ enum dc_status {
 };
 
 char *dc_status_to_str(enum dc_status status);
+char *dc_pixel_encoding_to_str(enum dc_pixel_encoding pixel_encoding);
+char *dc_color_depth_to_str(enum dc_color_depth color_depth);
 
 #endif /* _CORE_STATUS_H_ */