| Message ID | 20200228213607.23784-1-mario.kleiner.de@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/amd/display: Add link_rate quirk for Apple 15" MBP 2017 | expand |
Applied. Thanks! Alex On Fri, Feb 28, 2020 at 4:36 PM Mario Kleiner <mario.kleiner.de@gmail.com> wrote: > > 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> > --- > drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > 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) > 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, > -- > 2.20.1 > > _______________________________________________ > amd-gfx mailing list > amd-gfx@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/amd-gfx
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) 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,
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> --- drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 11 +++++++++++ 1 file changed, 11 insertions(+)