drm/amd/display: Force link_rate as LINK_RATE_RBR2 for 2018 15" Apple Retina panels

From Aun-Ali Zaidi
2093ecf557e733f995c7db6df716c91c43923972 in linux 5.15.y/5.15.22
30fbce374745a9c6af93c775a5ac49a97f822fda in mainline linux

diff --git a/sys/dev/pci/drm/amd/display/dc/core/dc_link_dp.c b/sys/dev/pci/drm/amd/display/dc/core/dc_link_dp.c
index d6405b0..0950206 100644 (file)
--- a/sys/dev/pci/drm/amd/display/dc/core/dc_link_dp.c
+++ b/sys/dev/pci/drm/amd/display/dc/core/dc_link_dp.c
@@ -3913,6 +3913,26 @@ static bool retrieve_link_cap(struct dc_link *link)
                dp_hw_fw_revision.ieee_fw_rev,
                sizeof(dp_hw_fw_revision.ieee_fw_rev));
 
+       /* Quirk for Apple MBP 2018 15" Retina panels: wrong DP_MAX_LINK_RATE */
+       {
+               uint8_t str_mbp_2018[] = { 101, 68, 21, 103, 98, 97 };
+               uint8_t fwrev_mbp_2018[] = { 7, 4 };
+               uint8_t fwrev_mbp_2018_vega[] = { 8, 4 };
+
+               /* We also check for the firmware revision as 16,1 models have an
+                * identical device id and are incorrectly quirked otherwise.
+                */
+               if ((link->dpcd_caps.sink_dev_id == 0x0010fa) &&
+                   !memcmp(link->dpcd_caps.sink_dev_id_str, str_mbp_2018,
+                            sizeof(str_mbp_2018)) &&
+                   (!memcmp(link->dpcd_caps.sink_fw_revision, fwrev_mbp_2018,
+                            sizeof(fwrev_mbp_2018)) ||
+                   !memcmp(link->dpcd_caps.sink_fw_revision, fwrev_mbp_2018_vega,
+                            sizeof(fwrev_mbp_2018_vega)))) {
+                       link->reported_link_cap.link_rate = LINK_RATE_RBR2;
+               }
+       }
+
        memset(&link->dpcd_caps.dsc_caps, '\0',
                        sizeof(link->dpcd_caps.dsc_caps));
        memset(&link->dpcd_caps.fec_cap, '\0', sizeof(link->dpcd_caps.fec_cap));