[Mesa-dev] [PATCH 1/3] vl/dri3: use external texture as back buffers

Andy Furniss adf.lists at gmail.com
Fri Oct 28 11:19:57 UTC 2016

Michel Dänzer wrote:
> On 27/10/16 07:52 PM, Andy Furniss wrote:
>> Andy Furniss wrote:
>>> Michel Dänzer wrote:
>>>> On 26/10/16 08:07 PM, Andy Furniss wrote:
>>>>> The bad = Starting with DRI3 (which is default) I still get trashed
>>>>> rendering full screen. Windowed including re-sizing seems OK.
>>>>> I use Fluxbox window manager, which does not use compositing -
>>>>> IIRC this has historically shown some ddx DRI2/3 issue that wasn't
>>>>> visible to those testing with compositing (but then the full screen
>>>>> case may avoid compositing anyway depending on settings).
>>>> You may be running into a DDX driver issue fixed by
>>>> https://patchwork.freedesktop.org/patch/118514/ .
>>> Yes, that was it, OK with that patch.
>> Though "OK", sub-optimal loosing pageflip on tonga, as a vsync test
>> fails top 5% of screen unless I force GPU perf high.
>> Not related to this patch directly of course, but I am a bit surprised
>> that on auto powerplay the tonga is too slow to make 60Hz.
> It's not too slow for 60 Hz (or you'd get dropped frames), the blit just
> doesn't finish within the vertical blank period.

Yea, I didn't word that very well, and also didn't say res (1080p)
making it even less useful.

Naive question = does the blit have to be "backwards", seems I wouldn't
notice if it were the same way as scanout?

I guess I am being far too simplistic here, not knowing even the most
basic detail, like what format is the actual framebuffer that gets
scanned out really kept in?

I know it ends up as BGR0 if grabbed by ffmpeg/gstreamer via X, which
leads to another thought/question. Currently to record screen with VCE
is quite bottle necked by copy to ram/convert to nv12 and copy back.

Are there any show stopping issues that would preclude avoiding the
copy and doing the CSC/subsample/nv12 layout all in vram/by GPU?

> Longer term I have an idea how to make the DDX driver support page
> flipping in this case as well, but in the meantime making the buffers
> sent for presentation tiled instead of linear should allow page flipping
> to be used. https://patchwork.freedesktop.org/patch/110569/ might be
> enough, which seems to be the best candidate to resolve the nouveau
> VDPAU issues as well.

Doesn't help (one quick test with ddx patch).

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