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| author | Mario Kleiner <mario.kleiner.de@gmail.com> | 2020-02-28 22:36:07 +0100 |
|---|---|---|
| committer | Alex Deucher <alexander.deucher@amd.com> | 2020-03-13 16:52:35 +0100 |
| commit | 473e3f7720f652716eb7a5b8f49628d6f66b1e87 (patch) | |
| tree | 4bf5917d71c0e950547ec69a6261a85d6129d0cf /drivers/gpu | |
| parent | drm/amdgpu: Stop using the DRIVER debugging flag for vblank debugging messages (diff) | |
| download | linux-473e3f7720f652716eb7a5b8f49628d6f66b1e87.tar.xz linux-473e3f7720f652716eb7a5b8f49628d6f66b1e87.zip | |
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')
| -rw-r--r-- | drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 11 |
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 9553755be286..f822049cc590 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 @@ -3438,6 +3438,17 @@ static bool retrieve_link_cap(struct dc_link *link) sink_id.ieee_device_id, sizeof(sink_id.ieee_device_id)); + /* 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; + } + } + core_link_read_dpcd( link, DP_SINK_HW_REVISION_START, |