drm/amd/display: Fix potential integer wraparound resulting in a hang

[Why]
If VUPDATE_END is before VUPDATE_START the delay calculated can become
very large, causing a soft hang.

[How]
Take the absolute value of the difference between START and END.

Signed-off-by: Aric Cyr <aric.cyr@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Aric Cyr 2020-05-12 11:48:48 -04:00 • committed by Alex Deucher
commit 185082b679