Three recent blog postings on DRI3000

[Keith Packard]

"Alexander E. Patrakov" <patrakov at gmail.com> writes:

> 2013/7/26 Keith Packard <keithp at keithp.com>:
>> "Alexander E. Patrakov" <patrakov at gmail.com> writes:
>>
>>> Which frame?
>>>
>>> Suppose that there are two overlapping outputs with vastly different
>>> refresh rates (say, an old 100 Hz CRT and a modern 60 Hz LCD).
>>
>> I'm afraid I just don't care very much about getting this case
>> 'right'. What Present (and DRI2 before it) does is to have the driver
>> just pick one of the outputs and use that as the MSC source.
>
> OK, let's try to get this case handled later (maybe in wayland), then.
> I am sure someone else will complain about the same thing, too,
> because even 59.93 Hz vs 60 Hz matters here.


> You are completely right here. The problem is that there is no way to
> influence the choice which monitor (especially in a cloned
> configuration) looks good. I.e., on my laptop (which I intend to bring
> to GUADEC), the Intel driver always seems to favor the internal panel
> if it is cloned to the Intel HDMI output. And in some cases (e.g. PAL
> movie playback) the judder is unavoidable on a typical 60-Hz-only
> monitor, so what one cares about is tearing.

I'm adding an explicit CRTC to the PresentRegion request (None == X
server picks). This will allow applications to select which monitor to
synchronize with.

> True. However, in theory, in the future, it should be possible to have
> two framebuffers, one for each output, displaying "the same thing" but
> updating independently (thus two blts, each synchronized to the
> correct refresh interval, thus achieving the same as below).

If they're not overlapping, you can just create two windows and update
them separately.

In any case, it looks like Present may make per-CRTC pixmaps pretty easy
to manage; just Present a pixmap in a full-monitor window and have the X
server flip to that just on that monitor. This seems like it should be a
pretty simple change at this point; right now, the flip is 'global', but
there's no particular reason to make it be that way.

-- 
keith.packard at intel.com
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