drm/amd/display: Detect dpcd_rev when hotplug mst monitor

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[Why]
Once mst topology is constructed, later on new connected monitors
are reported to source by CSN message. Within CSN, there is no
carried info of DPCD_REV comparing to LINK_ADDRESS reply. As the
result, we might leave some ports connected to DP but without DPCD
revision number which will affect us determining the capability of
the DP Rx.

[How]
Send out remote DPCD read when the port's dpcd_rev is 0x0 in
detect_ctx(). Firstly, read out the value from DPCD 0x2200. If the
return value is 0x0, it's likely the DP1.2 DP Rx then we reques
revision from DPCD 0x0 again.

Reviewed-by: Hersen Wu <hersenwu@amd.com>
Acked-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

...

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Wayne Lin 2022-04-20 10:32:15 +08:00 • committed by Alex Deucher

parent 84de5c2e92

commit 453b0016a0

1 changed files with 37 additions and 1 deletions

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drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c

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