[Linaro-mm-sig] V4L2 Overlay mode replacement by dma-buf - was: Re: [PATCH 05/10] v4l: add buffer exporting via dmabuf

Clark, Rob rob at ti.com
Tue Jan 24 00:11:06 UTC 2012


On Mon, Jan 23, 2012 at 10:57 AM, Mauro Carvalho Chehab
<mchehab at redhat.com> wrote:
>
>>> 2) The userspace API changes to properly support for dma buffers.
>>>
>>> If you're not ready to discuss (2), that's ok, but I'd like to follow
>>> the discussions for it with care, not only for reviewing the actual
>>> patches, but also since I want to be sure that it will address the
>>> needs for xawtv and for the Xorg v4l driver.
>>>
>>
>> The support of dmabuf could be easily added to framebuffer API.
>> I expect that it would not be difficult to add it to Xv.

You might want to have a look at my dri2video proposal a while back.
I plan some minor changes to make the api for multi-planar formats
look a bit more like how addfb2 ended up (ie. array of handles,
offsets, and pitches), but you could get the basic idea from:

http://patchwork.freedesktop.org/patch/7939/

> A texture based API is likely needed, at least for it to work with
> modern PC GPU's.

I suspect we will end up w/ an eglImage extension to go dmabuf fd <->
eglImage, and perhaps handle barriers and userspace mappings.  That
should, I think, be the best approach to best hide/abstract all the
GPU crazy games from the rest of the world.

BR,
-R



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