[Intel-gfx] [RFC PATCH 0/3] drm driver for baytrail's vxd392

[Stéphane Marchesin]

On Wed, Oct 15, 2014 at 1:13 AM, Thierry Reding <thierry.reding at gmail.com>
wrote:

> On Tue, Oct 14, 2014 at 08:50:35AM -0700, Sean V Kelley wrote:
> > On Tue, Oct 14, 2014 at 4:53 AM, Thierry Reding
> > <thierry.reding at gmail.com> wrote:
> > > On Mon, Oct 13, 2014 at 08:15:00PM +0800, Yao Cheng wrote:
> > >> drm/ipvr is a new GEM driver for baytrail's vxd392, which accelerates
> VP8 video decoding.
> > >> The driver name "ipvr" means the PowerVR's IP wrapped by Intel. In
> the future, ipvr may support other platforms such as Merrifield.
> > >> Code is placed at drivers/gpu/drm/ipvr and the following two new
> Kconfig are added:
> > >>   CONFIG_DRM_IPVR: Build option for ipvr module
> > >>   CONFIG_DRM_IPVR_EC: Experimental feature of error concealment
> > >>
> > >> User mode drm helper "libdrm_ipvr.so" and simple test are also
> included.
> > >>
> > >> Yao Cheng (3):
> > >>  [1/3] drm/i915: add vxd392 bridge in i915 on baytrail
> > >>  [2/3] drm/ipvr: ipvr drm driver for vxd392
> > >
> > > If this is Intel-specific, why doesn't it live under the i915 driver?
> >
> > It is an entirely unrelated HW IP block, VXD392.  Nothing to do with
> > GEN aside from DRM based.
>
> With GEN you're referring to the Intel integrated GPU? And VXD392 I take
> it is the IP block licensed by Imagination? Baytrail and others then
> wrap some additional logic around this as it is integrated into the SoC?
>
> How much wrapping actually happens here? I worry that this is going to
> lead to a lot of duplication if we ever want to support another SoC that
> uses the VXD392 IP. Could the code be split into a VXD392 "library" and
> some driver that implements the Intel-specific glue?
>
> Finally, if this IP block is a VP8 video decoding engine only, I'm not
> sure DRM is the best subsystem for it. Traditionally video decoding has
> been done primarily in V4L2. I'm not sure that's the best fit given that
> it was originally designed for video capturing, but they've evolved some
> infrastructure to deal with encoding/decoding, whereas we have nothing
> like that at all in DRM.
>

That isn't true. i915, nouveau and radeon drm drivers all support video
decoding user space in some form.

Stéphane
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