Fangzhi Zuo 16f2e14ee9 drm/amd/display: Skip Check Runtime Link Setting for Specific Branch Device
[why]
Read link setting inside mode validation is not always the final downlink setting.
It is found true in Synaptics branch device.

At bootup, the preferred mode being set right after 1080p is set. It occurred
before graphic load. That modeset switch in a short period of time makes
the branch device switch back and forth from lower and higher link rate,
observed at Synaptics branch device.
DP2 RTK hub on the other hand, sticks to highest available downlink rate after bootup.

Existing check of runtime downlink setting in mode validation shows asynchronous at
branch device link switch, i.e., downlink switch to higher link rate not yet complete
when the mode validation tries to probe the downlink setting. That makes mode validation
checking downlink setting making wrong decision by pruning modes that should pass the
validation after the downlink setting switch is complete.

[how]
If Synaptics is found at the last branch, skip checking downlink setting
at mode validation.

Reviewed-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Fangzhi Zuo <Jerry.Zuo@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
2025-08-29 10:23:09 -04:00
2025-06-11 11:57:14 -07:00
2025-06-15 13:49:41 -07:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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