drm/amd/display: Cap DSC bpp for USB4 DP tunnels

On pre-DCN4.2 platforms, USB4 DP bandwidth allocation is unavailable.
SST and MST streams are sized against their native DP link bandwidth
even when multiple DP tunnels share the host router. A high-bandwidth
DSC stream can consume too much shared tunnel capacity and cause
intermittent display corruption when another tunnel is active.

Cap the DSC target at 8 bpp for USB4 DPIA SST and MST streams when
bandwidth allocation is unavailable. For MST, cap the DSC fairness
range while preserving its per-link allocation. When bandwidth
allocation is enabled on DCN4.2, retain forced DSC and the existing
minimum-bpp behavior required to fit the tunnel grant.

This is a follow-up to commit c30b9813bce1 ("drm/amd/display: Force DSC
to 8bpp for SST DP tunneling over USB4") and commit cd53dcd2a7d7
("drm/amd/display: Force DSC to 8bpp for MST DP tunneling over USB4").

Reviewed-by: Ivan Lipski <ivan.lipski@amd.com>
Signed-off-by: Fangzhi Zuo <jerry.zuo@amd.com>
Signed-off-by: Tom Chung <chiahsuan.chung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit e2bd5d908a89252ad4ee11a3dbc9fd57c257accd)

0 files changed, 0 insertions, 0 deletions