From: Aun-Ali Zaidi admin@kodeit.net
commit 30fbce374745a9c6af93c775a5ac49a97f822fda upstream.
The eDP link rate reported by the DP_MAX_LINK_RATE dpcd register (0xa) is contradictory to the highest rate supported reported by EDID (0xc = LINK_RATE_RBR2). The effects of this compounded with commit '4a8ca46bae8a ("drm/amd/display: Default max bpc to 16 for eDP")' results in no display modes being found and a dark panel.
For now, simply force the maximum supported link rate for the eDP attached 2018 15" Apple Retina panels.
Additionally, we must also check the firmware revision since the device ID reported by the DPCD is identical to that of the more capable 16,1, incorrectly quirking it. We also use said firmware check to quirk the refreshed 15,1 models with Vega graphics as they use a slightly newer firmware version.
Tested-by: Aun-Ali Zaidi admin@kodeit.net Reviewed-by: Harry Wentland harry.wentland@amd.com Signed-off-by: Aun-Ali Zaidi admin@kodeit.net Signed-off-by: Aditya Garg gargaditya08@live.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+)
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c @@ -3587,6 +3587,26 @@ static bool retrieve_link_cap(struct dc_ 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));