[RFC] Support for H.264/MPEG4 encoder (VPU) in i.MX27.

Sascha Hauer s.hauer at pengutronix.de
Fri Jun 8 04:48:02 EDT 2012

On Fri, Jun 08, 2012 at 09:39:15AM +0200, javier Martin wrote:
> Hi Robert,
> On 8 June 2012 09:26, Robert Schwebel <r.schwebel at pengutronix.de> wrote:
> > Hi Javier,
> >
> > On Fri, Jun 08, 2012 at 09:21:13AM +0200, javier Martin wrote:
> >> If you refer to driver in [1] I have some concerns: i.MX27 VPU should
> >> be implemented as a V4L2 mem2mem device since it gets raw pictures
> >> from memory and outputs encoded frames to memory (some discussion
> >> about the subject can be fond here [2]), as Exynos driver from Samsung
> >> does. However, this driver you've mentioned doesn't do that: it just
> >> creates several mapping regions so that the actual functionality is
> >> implemented in user space by a library provided by Freescale, which
> >> regarding i.MX27 it is also GPL.
> >>
> >> What we are trying to do is implementing all the functionality in
> >> kernel space using mem2mem V4L2 framework so that it can be accepted
> >> in mainline.
> >
> > We will work on the VPU driver and it's migration towards a proper
> > mem2mem device very soon, mainly on MX53, but of course MX27 should be
> > taken care of by the same driver.
> >
> > So I'd suggest that we coordinate that work somehow.
> Do you plan to provide both encoding and decoding support or just one of them?

We have both encoding and decoding. It works on i.MX51/53, but was
originally written for i.MX27 aswell. I haven't tested i.MX27 for longer
now, so it might or might not work. Find the source here:


The main difference from the FSL code is that the whole VPU
functionality is in a kernel module which talks (mostly) v4l2. Our next
taks is to convert this into a real mem2mem device, right now it only
works with the included gstreamer plugin. You'll need a small kernel
patch to register the device and to add the clocks.

The gstreamer plugin is in a horrible state, but with the conversion to
mem2mem we hope to get rid of this entirely.


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