drm/amd/display: check dpcd read status of DP_DOWNSTREAM_PORT_0

[Why]
For special DP convert VGA dongle, core_link_read_dpcd for
DP_DOWNSTREAM_PORT_0 always return fail, then dongle_type will be set to
DISPLAY_DONGLE_NONE, which will cause desktop resolution abnormal.

[How]
If dpcd for DP_DOWNSTREAM_PORT_0 read fail, skip set dongle_type =
DISPLAY_DONGLE_NONE.
Signed-off-by: jinlong zhang <jinlong.zhang@amd.com>
Reviewed-by: Wenjing Liu <Wenjing.Liu@amd.com>
Acked-by: Eryk Brol <eryk.brol@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -3097,62 +3097,63 @@ static void get_active_converter_info(
 		uint8_t det_caps[16]; /* CTS 4.2.2.7 expects source to read Detailed Capabilities Info : 00080h-0008F.*/
 		union dwnstream_port_caps_byte0 *port_caps =
 			(union dwnstream_port_caps_byte0 *)det_caps;
-		core_link_read_dpcd(link, DP_DOWNSTREAM_PORT_0,
-				det_caps, sizeof(det_caps));
+		if (core_link_read_dpcd(link, DP_DOWNSTREAM_PORT_0,
+				det_caps, sizeof(det_caps)) == DC_OK) {
 
-		switch (port_caps->bits.DWN_STRM_PORTX_TYPE) {
-		/*Handle DP case as DONGLE_NONE*/
-		case DOWN_STREAM_DETAILED_DP:
-			link->dpcd_caps.dongle_type = DISPLAY_DONGLE_NONE;
-			break;
-		case DOWN_STREAM_DETAILED_VGA:
-			link->dpcd_caps.dongle_type =
-				DISPLAY_DONGLE_DP_VGA_CONVERTER;
-			break;
-		case DOWN_STREAM_DETAILED_DVI:
-			link->dpcd_caps.dongle_type =
-				DISPLAY_DONGLE_DP_DVI_CONVERTER;
-			break;
-		case DOWN_STREAM_DETAILED_HDMI:
-		case DOWN_STREAM_DETAILED_DP_PLUS_PLUS:
-			/*Handle DP++ active converter case, process DP++ case as HDMI case according DP1.4 spec*/
-			link->dpcd_caps.dongle_type =
-				DISPLAY_DONGLE_DP_HDMI_CONVERTER;
-
-			link->dpcd_caps.dongle_caps.dongle_type = link->dpcd_caps.dongle_type;
-			if (ds_port.fields.DETAILED_CAPS) {
-
-				union dwnstream_port_caps_byte3_hdmi
-					hdmi_caps = {.raw = det_caps[3] };
-				union dwnstream_port_caps_byte2
-					hdmi_color_caps = {.raw = det_caps[2] };
-				link->dpcd_caps.dongle_caps.dp_hdmi_max_pixel_clk_in_khz =
-					det_caps[1] * 2500;
-
-				link->dpcd_caps.dongle_caps.is_dp_hdmi_s3d_converter =
-					hdmi_caps.bits.FRAME_SEQ_TO_FRAME_PACK;
-				/*YCBCR capability only for HDMI case*/
-				if (port_caps->bits.DWN_STRM_PORTX_TYPE
-						== DOWN_STREAM_DETAILED_HDMI) {
-					link->dpcd_caps.dongle_caps.is_dp_hdmi_ycbcr422_pass_through =
-							hdmi_caps.bits.YCrCr422_PASS_THROUGH;
-					link->dpcd_caps.dongle_caps.is_dp_hdmi_ycbcr420_pass_through =
-							hdmi_caps.bits.YCrCr420_PASS_THROUGH;
-					link->dpcd_caps.dongle_caps.is_dp_hdmi_ycbcr422_converter =
-							hdmi_caps.bits.YCrCr422_CONVERSION;
-					link->dpcd_caps.dongle_caps.is_dp_hdmi_ycbcr420_converter =
-							hdmi_caps.bits.YCrCr420_CONVERSION;
+			switch (port_caps->bits.DWN_STRM_PORTX_TYPE) {
+			/*Handle DP case as DONGLE_NONE*/
+			case DOWN_STREAM_DETAILED_DP:
+				link->dpcd_caps.dongle_type = DISPLAY_DONGLE_NONE;
+				break;
+			case DOWN_STREAM_DETAILED_VGA:
+				link->dpcd_caps.dongle_type =
+					DISPLAY_DONGLE_DP_VGA_CONVERTER;
+				break;
+			case DOWN_STREAM_DETAILED_DVI:
+				link->dpcd_caps.dongle_type =
+					DISPLAY_DONGLE_DP_DVI_CONVERTER;
+				break;
+			case DOWN_STREAM_DETAILED_HDMI:
+			case DOWN_STREAM_DETAILED_DP_PLUS_PLUS:
+				/*Handle DP++ active converter case, process DP++ case as HDMI case according DP1.4 spec*/
+				link->dpcd_caps.dongle_type =
+					DISPLAY_DONGLE_DP_HDMI_CONVERTER;
+
+				link->dpcd_caps.dongle_caps.dongle_type = link->dpcd_caps.dongle_type;
+				if (ds_port.fields.DETAILED_CAPS) {
+
+					union dwnstream_port_caps_byte3_hdmi
+						hdmi_caps = {.raw = det_caps[3] };
+					union dwnstream_port_caps_byte2
+						hdmi_color_caps = {.raw = det_caps[2] };
+					link->dpcd_caps.dongle_caps.dp_hdmi_max_pixel_clk_in_khz =
+						det_caps[1] * 2500;
+
+					link->dpcd_caps.dongle_caps.is_dp_hdmi_s3d_converter =
+						hdmi_caps.bits.FRAME_SEQ_TO_FRAME_PACK;
+					/*YCBCR capability only for HDMI case*/
+					if (port_caps->bits.DWN_STRM_PORTX_TYPE
+							== DOWN_STREAM_DETAILED_HDMI) {
+						link->dpcd_caps.dongle_caps.is_dp_hdmi_ycbcr422_pass_through =
+								hdmi_caps.bits.YCrCr422_PASS_THROUGH;
+						link->dpcd_caps.dongle_caps.is_dp_hdmi_ycbcr420_pass_through =
+								hdmi_caps.bits.YCrCr420_PASS_THROUGH;
+						link->dpcd_caps.dongle_caps.is_dp_hdmi_ycbcr422_converter =
+								hdmi_caps.bits.YCrCr422_CONVERSION;
+						link->dpcd_caps.dongle_caps.is_dp_hdmi_ycbcr420_converter =
+								hdmi_caps.bits.YCrCr420_CONVERSION;
+					}
+
+					link->dpcd_caps.dongle_caps.dp_hdmi_max_bpc =
+						translate_dpcd_max_bpc(
+							hdmi_color_caps.bits.MAX_BITS_PER_COLOR_COMPONENT);
+
+					if (link->dpcd_caps.dongle_caps.dp_hdmi_max_pixel_clk_in_khz != 0)
+						link->dpcd_caps.dongle_caps.extendedCapValid = true;
 				}
 
-				link->dpcd_caps.dongle_caps.dp_hdmi_max_bpc =
-					translate_dpcd_max_bpc(
-						hdmi_color_caps.bits.MAX_BITS_PER_COLOR_COMPONENT);
-
-				if (link->dpcd_caps.dongle_caps.dp_hdmi_max_pixel_clk_in_khz != 0)
-					link->dpcd_caps.dongle_caps.extendedCapValid = true;
+				break;
 			}
-
-			break;
 		}
 	}