drm/amd/display: Fix fast updates on DCE 6.x

DCE6 should use legacy fast updates, just like all DCE8 - DCN2.
Set that flag for DCE 6.0, 6.1 and 6.4 (all DCE6 versions).

Technically DCE6 should have been included when the fast update
code was refactored, but it just happened to work until now.

A recent commit "Attach only plane updates that actually changed"
has exposed this issue because with that commit, DC accidentally
took the new fast update code path for DCE6 as well, which caused
it to boot into a black screen with a flip done timeout.

This fix should be backported to all kernel versions that
have "Refactor fast update to use new HWSS build sequence",
but this patch won't apply cleanly to older kernels due to
another refactor in "Remove dc param from check_update".

Fixes: 0baae62463 ("drm/amd/display: Refactor fast update to use new HWSS build sequence")
Fixes: 9ec11bb842 ("drm/amd/display: Remove dc param from check_update")
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://patch.msgid.link/20260923122033.1046651-1-timur.kristof@gmail.com
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Timur Kristóf 2026-09-23 14:20:31 +02:00 • committed by Alex Deucher
commit 698fda6e36