Messages in this thread | | | Subject | Re: [PATCH v9 5/7] vfio: Define vfio based dma-buf operations | From | Gerd Hoffmann <> | Date | Tue, 20 Jun 2017 10:35:03 +0200 |
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Hi,
> > Hmm, plane isn't really an ID, it is a type, with type being either > > DRM_PLANE_TYPE_PRIMARY or DRM_PLANE_TYPE_CURSOR, so I don't think > > the > > flage above make sense. > > The intention was that ..._REGION_ID and ...PLANE_ID are describing > what the vfio_device_query_gfx_plane.id field represents, either a > region index or a plane identifier. The type of plane would be > represented within the vfio_device_gfx_plane_info struct.
The planes don't really have an id, we should rename that to plane_type, or maybe drm_plane_type (simliar to the drm_format_* fields), to avoid that confusion.
plane_type is set by userspace to specify what kind of plane it asks for.
> > Also I think it would be useful to have some way to figure the > > device > > capabilities as the userspace workflow will look quite different > > for > > the two cases. > > In the region case, VFIO_DEVICE_GET_REGION_INFO would include a > device > specific region with a hopefully common identifier to identify it as > a > graphics framebuffer.
Ok, that should work to figure whenever the mdev supports a plane region or not.
> In the dmabuf case,VFIO_DEVICE_QUERY_GFX_PLANE would indicate the > plane as a "plane ID" and some sort of > VFIO_DEVICE_GET_GFX_PLANE(VFIO_GFX_TYPE_DMABUF) ioctl would be > necessary to get a file descriptor to that plane. > > What else are you thinking we need? Thanks,
I need to know whenever the mdev supports dmabufs or not, at device initialization time (because dmabufs require opengl support), when VFIO_DEVICE_QUERY_GFX_PLANE doesn't work due to the guest not having the device initialized yet.
Maybe we should have a error field in the ioctl struct, or we need to clearly define error codes so the kernel doesn't just throw EINVAL in all cases.
Or just a VFIO_DEVICE_GFX_CAPS ioctl which returns NONE, REGION or DMABUF.
cheers, Gerd
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