[Intel-gfx] [SNB] video tearing (wait for scanline support patch)

[Eric Anholt]

On Mon, 6 Jun 2011 21:30:19 +0400, Dmitry Savin <envelsavinds at gmail.com> wrote:
> Hi,
> I've made the following patch for Gen6 wait for scanline support.
> pixmap_is_scanout always gives FALSE. What does it really mean? When I
> comment it I've got GPU lock up while waiting for scanline. According to
> specs I loaded DE_LOAD_SL register but it seems to me that it doesn't work.
> Finally, I've tested it with only wait for VBLANK. And as you may suggest it
> didn't help. The same tearing issue happens with even 1st generation Core
> video. Why am I wrong? Patch made for 2.14.0.

You can't wait_for_event on scanlines in the BLT ring, so you'd want the
swap to be done using the 3D engine and have it preceded by a wait for
scanline there (if it works).
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