LinCheng Ku ca36d953d7 drm/amd/display: Add USB-C DP Alt Mode lane limitation in DCN32 ...

[ Upstream commit cea573a8e1 ]

[Why]
USB-C DisplayPort Alt Mode with concurrent USB data needs lane count
limitation to prevent incorrect 4-lane DP configuration when only 2 lanes
are available due to hardware lane sharing between DP and USB3.

[How]
Query DMUB for Alt Mode status (is_dp_alt_disable, is_usb, is_dp4) in
dcn32_link_encoder_get_max_link_cap() and cap DP to 2 lanes when USB is
active on USB-C port. Added inline documentation explaining the USB-C
lane sharing constraint.

Reviewed-by: PeiChen Huang <peichen.huang@amd.com>
Signed-off-by: LinCheng Ku <lincheng.ku@amd.com>
Signed-off-by: Chenyu Chen <chen-yu.chen@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

2026-03-04 07:21:00 -05:00

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dcn10

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dcn20

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dcn30

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dcn31

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dcn32

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dcn35

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dcn301

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dcn314

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dcn321

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dcn401

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Makefile

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