Bill Dirks wrote:
> Chris Worley wrote:
> > My video hardware and frame buffer are tightly integrated (a capture
> > engine that receives decoded video input on the front end of a
> > non-visible portion of the frame buffer, and an overlay engine that
> > blends the video and graphics on the back end for output). I think
> > this tight integration will be used by many cards in the future (video
> > and graphics cards will be the same, as with the ATI All-In-Wonder,
> > and Matrox Marvel).
> >
> > The frame buffer memory used by the video hardware must be accounted
> > for and managed from user space, but it should be the V4L driver that
> > responds with the amount of memory currently required by the video
> > hardware.
> > [...]
> > Should the V4L2 specification be adjusted for this consideration? Or,
> > how best would this be implemented?
>
>
> This is normally done by creating custom ioctls.
No. This is not different from dma-to-userspace (which we need a new
API / API extention for anyway). The application just passes a userspace
pointer to the driver and asks it to transfer the video data to that
location. That might be simply malloc()ed memory, a MIT-SHM segment,
a pointer to the mmap()ed video framebuffer, whatever...
Gerd
--
Get back there in front of the computer NOW. Christmas can wait.
-- Linus "the Grinch" Torvalds, 24 Dec 2000 on linux-kernel
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