[Intel-gfx] Page flipping not working as expected for compositing - engineering resource available to help fix it

[Andrew Lutomirski]

On Mon, May 10, 2010 at 12:59 PM, Simon Farnsworth
<simon.farnsworth at onelan.com> wrote:
> On Monday 10 May 2010, Simon Farnsworth <simon.farnsworth at onelan.com> wrote:
>> On Friday 7 May 2010, Simon Farnsworth <simon.farnsworth at onelan.com> wrote:
>> > I've attached my test program (it's based on our C++ OpenGL compositor,
>> > but cut down to just test OpenGL pageflipping) as performance.c, and my
>> > test X stack's Xorg.0.log after one run of "performance -indirect"
>> > (which ran for 573 frames). I'm using a 32-bit PAE kernel - I can add
>> > information as required, and I'm happy to run tests or experiments for
>> > people.
>> >
>> > 2) How should I go about fixing compositing? Should I fix indirect
>> > rendering to use pageflipping (and if so, where do I start looking for
>> > the code that's getting it wrong), or should I make TFP work when direct
>> > rendering (and again, where should I start looking)?
>>
>> Is this the expected behaviour when indirect rendering? If so, I'll dive
>> back into the stack and see if I can work out why TFP and direct rendering
>> don't interact nicely. If not, roughly where should I look to fix it?
>
> I've found why direct rendering and TFP don't interact nicely, and it's a
> client side error.
>
> Briefly, my compositor was being started as our signage user, who does not have
> access to /dev/dri/card0, so was falling back to swrast. When you're using
> swrast, TFP only appears to work for pixmaps you create, not for compositing
> pixmaps.

Your program still fails for me running as an ordinary user (with, I'm
pretty sure, all necessary rights) when compositing is enabled.

--Andy