Re: [st-ericsson] v4l2 vs omx for camera

[Hans Verkuil <hansverk@cisco.com>]

On Monday, February 28, 2011 11:11:47 Laurent Pinchart wrote:
> On Saturday 26 February 2011 13:12:42 Hans Verkuil wrote:
> > On Friday, February 25, 2011 18:22:51 Linus Walleij wrote:
> > > 2011/2/24 Edward Hervey <bilboed@gmail.com>:
> > > >  What *needs* to be solved is an API for data allocation/passing at 
the
> > > > 
> > > > kernel level which v4l2,omx,X,GL,vdpau,vaapi,... can use and that
> > > > userspace (like GStreamer) can pass around, monitor and know about.
> > > 
> > > I think the patches sent out from ST-Ericsson's Johan Mossberg to
> > > linux-mm for "HWMEM" (hardware memory) deals exactly with buffer
> > > passing, pinning of buffers and so on. The CMA (Contigous Memory
> > > Allocator) has been slightly modified to fit hand-in-glove with HWMEM,
> > > so CMA provides buffers, HWMEM pass them around.
> > > 
> > > Johan, when you re-spin the HWMEM patchset, can you include
> > > linaro-dev and linux-media in the CC?
> > 
> > Yes, please. This sounds promising and we at linux-media would very much
> > like to take a look at this. I hope that the CMA + HWMEM combination is
> > exactly what we need.
> 
> Once again let me restate what I've been telling for some time: CMA must be 
> *optional*. Not all hardware need contiguous memory. I'll have a look at the 
> next HWMEM version.

Yes, it is optional when you look at specific hardware. On a kernel level 
however it is functionality that is required in order to support all the 
hardware. There is little point in solving one issue and not the other.

Regards,

	Hans