[Mesa-dev] DRM EGL swapbuffers?

[Chia-I Wu]

On Tue, Feb 22, 2011 at 1:56 AM, Thomas Hellstrom <thomas at shipmail.org> wrote:
> Hi, Chia-I,
>
> Looking at the EGL DRM implementation of swapbuffers, it looks like we're
> sort of ad-hoc attaching the backbuffer as a new scanout surface, using
> drmModeSetCrtc.
>
> I don't think this works very well on all hardware. In particular, I think
> drmModeSetCrtc may return before the swap actually takes place, which will
> cause rendering to the old front buffer while it is still displaying.
>
> Could you fill me in why the pageflip ioctl isn't used here, and a surface
> copy in situations where the pageflip ioctl can't be used? IIRC, the
> pageflip ioctl is required to block rendering to the old frontbuffer until
> the new frontbuffer is flipped in.
Yes, pageflip should be used when available.  I did not use it simply
because it was not available on my machine when the code was written,
and I haven't had the motivation to revisit the code yet..

> Thanks,
> Thomas
>
>
>
>
>



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