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Message-ID: <1497854053.4207.2.camel@redhat.com>
Subject: Re: [PATCH v9 5/7] vfio: Define vfio based dma-buf operations
From: Gerd Hoffmann <kraxel@redhat.com>
To: Alex Williamson <alex.williamson@redhat.com>,
        Kirti Wankhede <kwankhede@nvidia.com>
Cc: Xiaoguang Chen <xiaoguang.chen@intel.com>, chris@chris-wilson.co.uk,
        intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        zhenyuw@linux.intel.com, zhiyuan.lv@intel.com,
        intel-gvt-dev@lists.freedesktop.org, zhi.a.wang@intel.com,
        kevin.tian@intel.com
Date: Mon, 19 Jun 2017 08:34:13 +0200
In-Reply-To: <20170616103959.3b6f1681@t450s.home>
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         <f19da207-a7f5-d3d3-4577-b071e7d75cf7@nvidia.com>
         <1497542438.29252.1.camel@redhat.com> <20170615143833.7526351b@w520.home>
         <24c4880b-24f5-ea07-834c-c77d3e895c78@nvidia.com>
         <20170616103959.3b6f1681@t450s.home>
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  Hi,

> So perhaps this becomes:
> 
> struct vfio_device_gfx_plane_info {
> 	__u64 start;
> 	__u64 drm_format_mod;
> 	__u32 drm_format;
> 	__u32 width;
> 	__u32 height;
> 	__u32 stride;
> 	__u32 size;
> 	__u32 x_pos;
> 	__u32 y_pos;
> };

Looks good.

> struct vfio_device_query_gfx_plane {
> 	__u32 argsz;
> 	__u32 flags;
> #define VFIO_GFX_PLANE_FLAGS_REGION_ID		(1 << 0)
> #define VFIO_GFX_PLANE_FLAGS_PLANE_ID		(1 << 1)
> 	struct vfio_device_gfx_plane_info plane_info;
> 	__u32 id; 
> };

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.

What are the nvidia plane for cursor support btw?

> The flag defines the data in the id field as either referring to a
> region (perhaps there could be multiple regions with only one active)

Well, we have a "start" field in vfio_device_gfx_plane_info (maybe we
should rename that to "offset"), which can be used to place multiple
planes into a single, fixed region.

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.

cheers,
  Gerd