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

[Thierry Reding]

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.

Thierry
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