[PATCH v10] vfio: ABI for mdev display dma-buf operation

[Zhang, Tina]

> -----Original Message-----
> From: intel-gvt-dev [mailto:intel-gvt-dev-bounces at lists.freedesktop.org] On
> Behalf Of Daniel Vetter
> Sent: Tuesday, July 11, 2017 5:13 PM
> To: Gerd Hoffmann <kraxel at redhat.com>
> Cc: Tian, Kevin <kevin.tian at intel.com>; linux-kernel at vger.kernel.org; intel-
> gfx at lists.freedesktop.org; alex.williamson at redhat.com;
> zhenyuw at linux.intel.com; chris at chris-wilson.co.uk; Kirti Wankhede
> <kwankhede at nvidia.com>; Lv, Zhiyuan <zhiyuan.lv at intel.com>;
> daniel at ffwll.ch; Zhang, Tina <tina.zhang at intel.com>; intel-gvt-
> dev at lists.freedesktop.org; Wang, Zhi A <zhi.a.wang at intel.com>
> Subject: Re: [PATCH v10] vfio: ABI for mdev display dma-buf operation
> 
> On Tue, Jul 11, 2017 at 08:14:08AM +0200, Gerd Hoffmann wrote:
> >   Hi,
> >
> > > > +struct vfio_device_query_gfx_plane {
> > > > +	__u32 argsz;
> > > > +	__u32 flags;
> > > > +	struct vfio_device_gfx_plane_info plane_info;
> > > > +	__u32 plane_type;
> > > > +	__s32 fd; /* dma-buf fd */
> > > > +	__u32 plane_id;
> > > > +};
> > > > +
> > >
> > > It would be better to have comment here about what are expected
> > > values for plane_type and plane_id.
> >
> > plane_type is DRM_PLANE_TYPE_*.
> >
> > yes, a comment saying so would be good, same for drm_format which is
> > DRM_FORMAT_*.  While looking at these two: renaming plane_type to
> > drm_plane_type (for consistency) is probably a good idea too.
> >
> > plane_id needs a specification.
> 
> Why do you need plane_type? With universal planes the plane_id along is
> sufficient to identify a plane on a given drm device instance. I'd just remove it.
> -Daniel
The plane_type here, is to ask the mdev vendor driver to return the information according to the value in field plane_type. So, it's a input field.
The values in plane_type field is the same of drm_plane_type. And yes, it's better to use drm_plane_type instead of plane_id. 
Thanks.

Tina
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
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