[Bug 102774] [BDW] [Bisected] Absolute constant buffers break VAAPI in mpv

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=102774

Kenneth Graunke <kenneth at whitecape.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |chris at chris-wilson.co.uk,
                   |                            |daniel at ffwll.ch

--- Comment #14 from Kenneth Graunke <kenneth at whitecape.org> ---
Daniel reminded me that X (Glamor) and GNOME Shell use Mesa, so my earlier
testing wasn't completely on Mesa 17.1.  I can now confirm the report (on
Kabylake).

mpv -hwdec=vaapi -vo=vaapi did indeed work with Mesa 17.1.  It misrenders or
GPU hangs with 17.2 and later (due to "i965: Switch to absolute addressing for
constant buffer 0").

I ran a few more experiments:

- Starting X/Glamor with 17.1 without a compositor...
  - mpv -hwdec=vaapi -vo=vaapi appears to work with any Mesa version
  - Running Piglit using Mesa 17.2+ concurrently with a working mpv works
fine...both mpv and Piglit work fine.

I think this suggests that CS_DEBUG_MODE2 is indeed saved and restored as part
of the context - Glamor and mpv (on 17.1) would expect relative mode, and
Piglit (on 17.2+) would expect absolute mode.  And both worked.  Daniel had
suggested there might be a bug where setting the mode made it take effect on
all rings, and that seems to not be the case either.

- Starting X/Glamor with 17.2+ without a compositor...
  - mpv -hwdec=vaapi -vo=vaapi misrenders and GPU hangs.

My theory is that new contexts are inheriting the state from X/Glamor's
context.  I'd say maybe it's because it gets the fd from X via DRI3...but that
doesn't make much sense, because libva-intel-driver doesn't use DRI3.  Maybe
it's because X is the first client on the system?  Or it's drm master?  Or runs
just before mpv?

Note that libva-intel-driver doesn't create its own context.  But I think the
kernel ought to make one for it, when it opens the fd...

Daniel, Chris, do you have any ideas?

-- 
You are receiving this mail because:
You are the QA Contact for the bug.
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/intel-3d-bugs/attachments/20170924/0aaa8680/attachment.html>