commit 787f41564acc6fbabed08976282b8907d6af7534
author Daniele Castagna <dcastagna@chromium.org> Tue Feb 12 17:05:05 2019
committer Commit Bot <commit-bot@chromium.org> Tue Feb 12 17:05:05 2019
tree 7bfaf2545d941f4433e9a357bc226f04213af0bc
parent d372d34ed2adf37d24a6c1c32c612dfd6900955e

cros: Disable explicit DMA fences

On Intel devices we noticed glitches when pageflipping that seem to
be caused by a race between GPU and display controller.
The glitches started appearing when we enabled explicit synchronization
for the primary plane.

Investigating further we discovered that we are currently inserting the
fence after GLRenderer draws all the contents, but before the bufferqueue
copies from the previous framebuffer, to the current framebuffer, to
implement partial swap. This means we can end up scanning out from an fb
while the GPU is copying parts of the previous fb to it.

This CL inverts the flag disable-explicit-dma-fences to a flag to enable
them, effectively disabling them by default while we fix the issue we
discovered.

Bug: 889530
Change-Id: Iea1e9d163228fc7df6389fbe730196af01ab3a51
Reviewed-on: https://chromium-review.googlesource.com/c/1462204
Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Reviewed-by: Michael Spang <spang@chromium.org>
Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Daniele Castagna <dcastagna@chromium.org>
Cr-Commit-Position: refs/heads/master@{#631272}