drm/amd/display: Fix surface optimization regression on Carrizo

[Why]
DCE legacy optimization path isn't well tested under new DC optimization
flow which can result in underflow occuring when initializing X11 on
Carrizo.

[How]
Retain the legacy optimization flow for DCE and keep the new one for DCN
to satisfy optimizations being correctly applied for ASIC that can
support it.

Fixes: 34316c1e56 ("drm/amd/display: Optimize bandwidth on following fast update")
Reported-by: Tom St Denis <tom.stdenis@amd.com>
Tested-by: Tom St Denis <tom.stdenis@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Nicholas Kazlauskas 2021-10-12 10:04:03 -04:00 • committed by Alex Deucher
commit 62e5a7e233