drm/amd/display: Fix pbn to kbps Conversion

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[Why]
Existing routine has two conversion sequence,
pbn_to_kbps and kbps_to_pbn with margin.
Non of those has without-margin calculation.

kbps_to_pbn with margin conversion includes
fec overhead which has already been included in
pbn_div calculation with 0.994 factor considered.
It is a double counted fec overhead factor that causes
potential bw loss.

[How]
Add without-margin calculation.
Fix fec overhead double counted issue.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3735
Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Fangzhi Zuo <Jerry.Zuo@amd.com>
Signed-off-by: Ivan Lipski <ivan.lipski@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit e0dec00f3d)
Cc: stable@vger.kernel.org

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This commit is contained in:

Fangzhi Zuo 2025-11-07 15:01:30 -05:00 • committed by Alex Deucher

parent 5bab4c8939

commit 1788ef3072

1 changed files with 23 additions and 36 deletions

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

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