path: root/drivers/gpu
diff options
authorMario Kleiner <mario.kleiner.de@gmail.com>2020-02-28 22:36:07 +0100
committerAlex Deucher <alexander.deucher@amd.com>2020-03-13 09:20:32 -0400
commitdec9de2ada523b344eb2428abfedf9d6cd0a0029 (patch)
treed2685ce494eb658e14617e8866ddcffbe54c6494 /drivers/gpu
parentdrm/amdgpu: add fbdev suspend/resume on gpu reset (diff)
drm/amd/display: Add link_rate quirk for Apple 15" MBP 2017
This fixes a problem found on the MacBookPro 2017 Retina panel: The panel reports 10 bpc color depth in its EDID, and the firmware chooses link settings at boot which support enough bandwidth for 10 bpc (324000 kbit/sec aka LINK_RATE_RBR2 aka 0xc), but the DP_MAX_LINK_RATE dpcd register only reports 2.7 Gbps (multiplier value 0xa) as possible, in direct contradiction of what the firmware successfully set up. This restricts the panel to 8 bpc, not providing the full color depth of the panel on Linux <= 5.5. Additionally, commit '4a8ca46bae8a ("drm/amd/display: Default max bpc to 16 for eDP")' introduced into Linux 5.6-rc1 will unclamp panel depth to its full 10 bpc, thereby requiring a eDP bandwidth for all modes that exceeds the bandwidth available and causes all modes to fail validation -> No modes for the laptop panel -> failure to set any mode -> Panel goes dark. This patch adds a quirk specific to the MBP 2017 15" Retina panel to override reported max link rate to the correct maximum of 0xc = LINK_RATE_RBR2 to fix the darkness and reduced display precision. Please apply for Linux 5.6+ to avoid regressing Apple MBP panel support. Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Diffstat (limited to 'drivers/gpu')
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
index cb731c1d30b1..fd9e69634c50 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
@@ -3401,6 +3401,17 @@ static bool retrieve_link_cap(struct dc_link *link)
+ /* Quirk Apple MBP 2017 15" Retina panel: Wrong DP_MAX_LINK_RATE */
+ {
+ uint8_t str_mbp_2017[] = { 101, 68, 21, 101, 98, 97 };
+ if ((link->dpcd_caps.sink_dev_id == 0x0010fa) &&
+ !memcmp(link->dpcd_caps.sink_dev_id_str, str_mbp_2017,
+ sizeof(str_mbp_2017))) {
+ link->reported_link_cap.link_rate = 0x0c;
+ }
+ }