Three recent blog postings on DRI3000

[Maarten Lankhorst]

Op 25-07-13 19:40, Keith Packard schreef:
> Keith Packard <keithp at keithp.com> writes:
>
>> Maarten Lankhorst <maarten.lankhorst at canonical.com> writes:
>>
>>> I just want the option of being able to specify an absolute time to
>>> synchronize to for the users, If opengl that wants to sync to a
>>> relative frame interval it can keep doing that.
>> That seems fine to me; it's gonna be a bunch of work to make it correct
>> though; you'll have to ask the kernel to translate a UST into an MSC for
>> a specific CRTC.
>>
>> Nah, probably not -- just getting the current UST/MSC pair and using the
>> refresh rate is probably sufficient to compute this in user space, or at
>> least close.
And this changes if the window is moved between crtc's, in the future it might even change
between graphics card correctly.
> If you're willing to do a proof-of-concept implementation, we can add it
> to the extension, but I don't want to specify anything that hasn't been
> implemented. We've done that a few times and deeply regretted it every time...
>
The presentation part of VDPAU (which may be implemented as overlay) offers something like this with
the VdpPresentationQueueDisplay call. But in dri2 it fails because the window can get moved between
2 crtc's, and suddenly you've queued a flip 1000 seconds in the future because the other crtc was
on for a shorter amount of time.. With the fence stuff I'm working on it should be possible to insert
a synchronization barrier in the command stream to a crtc that's not on the same graphics card, but
that really would require cooperation from the drm layer.

~Maarten