Commit 185082b6 authored May 12, 2020 by Aric Cyr Committed by Alex Deucher May 27, 2020

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>

parent 8d43e396

drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -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);
		}

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