drm/amd/display: Test link bandwidth readback

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[WHAT]
Add KUnit tests for dp_get_link_current_set_bw() covering every link
rate the helper knows about, the unknown rate fallback and the DPCD
read error path.

[HOW]
Add a DPCD backing store for the DSC helpers that is addressed
absolutely, because they read offsets spread across the whole map. A
table driven test then programs the link rate and lane count into the
fake DPCD and checks the returned bandwidth, with one entry arming the
AUX transfer to fail.

Assisted-by: Copilot:Claude-Opus-5
Reviewed-by: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
Signed-off-by: Alex Hung <alex.hung@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>

...

This commit is contained in:

Alex Hung 2026-08-30 01:04:24 -06:00 • committed by Alex Deucher

parent c091982756

commit 46395b55cb

3 changed files with 124 additions and 1 deletions

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3

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

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2

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

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120

drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_mst_types_test.c

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