Bug 206157 - Apple MacBookPro 2017 Retina panel doesn't reach 10 bit native precision due to low eDP link settings.
Summary: Apple MacBookPro 2017 Retina panel doesn't reach 10 bit native precision due ...
Alias: None
Product: Drivers
Classification: Unclassified
Component: Video(Other) (show other bugs)
Hardware: Intel Linux
: P1 normal
Assignee: drivers_video-other
Depends on:
Reported: 2020-01-10 15:46 UTC by Mario Kleiner
Modified: 2020-03-03 08:45 UTC (History)
0 users

See Also:
Kernel Version: 5.5-rc
Tree: Mainline
Regression: No

DPCD dump of the first ~5000 Bytes/Regs (4.89 KB, application/octet-stream)
2020-01-10 15:46 UTC, Mario Kleiner

Description Mario Kleiner 2020-01-10 15:46:13 UTC
Created attachment 286741 [details]
DPCD dump of the first ~5000 Bytes/Regs

The panel reports 10 bpc color depth in its EDID, and the UEFI
firmware chooses link settings at boot which support enough
bandwidth for 10 bpc (324000 kbit/sec to be precise, aka DP_LINK_BW_SET == 0xc), but the DP_MAX_LINK_RATE dpcd register only reports 0xa == 2.7 Gbps as possible,
so intel_dp_set_sink_rates() would cap at that. This restricts
achievable color depth to 8 bpc, not providing the full color
depth of the panel.

This report relates to dri-devel patch "drm/i915/dp: Add current maximum eDP link rate to sink_rate array."

Attached is a DPCD dump of the first ~ 5000 Bytes/Registers of the eDP panel.
Comment 1 Jani Nikula 2020-01-17 09:54:26 UTC
FWIW we don't really look at i915 bugs at bugzilla.kernel.org, except to tell you to report i915 bugs at https://gitlab.freedesktop.org/drm/intel/issues/new

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