On 02/22/2011 07:44 PM, Chia-I Wu wrote:
On Tue, Feb 22, 2011 at 1:56 AM, Thomas Hellstrom<tho...@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..
OK. I'd like to update the code to use pageflip when available and
otherwise fall back to a gallium blit. The current implementation really
has no way to sync with ongoing rendering, and even if a synchronization
method were implemented, draining the pipeline is generally a bad idea.
So what would the appropriate place be to implement an exported gallium
blit utility function, callable from the platform drivers?
Thanks,
Thomas
Thanks,
Thomas
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