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
parent 8d43e3966b
commit 185082b679
1 changed files with 2 additions and 0 deletions

View File

@ -1742,6 +1742,8 @@ static void delay_cursor_until_vupdate(struct dc *dc, struct pipe_ctx *pipe_ctx)
return;
/* Stall out until the cursor update completes. */
if (vupdate_end < vupdate_start)
vupdate_end += stream->timing.v_total;
us_vupdate = (vupdate_end - vupdate_start + 1) * us_per_line;
udelay(us_to_vupdate + us_vupdate);
}