On Wed, Aug 9, 2017 at 12:03 PM, Chris Wilson <ch...@chris-wilson.co.uk>
wrote:
> To further facilitate GEM testing, allow testing of drm_syncobj by
> attaching them to vgem fences. These fences are already employed by igt
> for testing inter-driver fence handling (across dmabuf and sync_file).
>
> An igt example use would be like:
>
> int vgem = drm_driver_open(DRIVER_VGEM);
> uint32_t handle = vgem_create_dummy(vgem);
>
This is a bit nasty... Why do we need a BO? Why can't we just create and
attach a fence without the BO?
> uint32_t syncobj = drm_syncobj_create(vgem);
> uint32_t fence = drmIoctl(vgem,
> DRM_IOCTL_VGEM_FENCE_ATTACH,
> &(struct vgem_fence_attach){
> .handle = handle,
> .flags = VGEM_FENCE_SYNCOBJ,
> .syncobj = syncobj,
> });
>
> /* ... use syncobj for profit ... */
>
> vgem_fence_signal(vgem, fence);
>
> For wider use though, there is little immediate benefit to syncobj
> over the vgem fence as both are handles in an idr (the fence here is not
> a sync-file fd like in most other drivers). The main benefit for syncobj
> is that it allows to create channels between objects and drivers by
> virtue of its persistence beyond the vgem fence itself.
>
> Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
> Cc: Jason Ekstrand <ja...@jlekstrand.net>
> Cc: Daniel Vetter <daniel.vet...@ffwll.ch>
> ---
> drivers/gpu/drm/vgem/vgem_drv.c | 4 +++-
> drivers/gpu/drm/vgem/vgem_fence.c | 26 ++++++++++++++++++++++----
> include/drm/drm_syncobj.h | 2 ++
> include/uapi/drm/vgem_drm.h | 3 ++-
> 4 files changed, 29 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_
> drv.c
> index 12289673f457..a0202e1eaf6b 100644
> --- a/drivers/gpu/drm/vgem/vgem_drv.c
> +++ b/drivers/gpu/drm/vgem/vgem_drv.c
> @@ -432,7 +432,9 @@ static void vgem_release(struct drm_device *dev)
> }
>
> static struct drm_driver vgem_driver = {
> - .driver_features = DRIVER_GEM | DRIVER_PRIME,
> + .driver_features = (DRIVER_GEM |
> + DRIVER_PRIME |
> + DRIVER_SYNCOBJ),
> .release = vgem_release,
> .open = vgem_open,
> .postclose = vgem_postclose,
> diff --git a/drivers/gpu/drm/vgem/vgem_fence.c
> b/drivers/gpu/drm/vgem/vgem_fence.c
> index 3109c8308eb5..988e860c03d3 100644
> --- a/drivers/gpu/drm/vgem/vgem_fence.c
> +++ b/drivers/gpu/drm/vgem/vgem_fence.c
> @@ -23,6 +23,8 @@
> #include <linux/dma-buf.h>
> #include <linux/reservation.h>
>
> +#include <drm/drm_syncobj.h>
> +
> #include "vgem_drv.h"
>
> #define VGEM_FENCE_TIMEOUT (10*HZ)
> @@ -156,20 +158,30 @@ int vgem_fence_attach_ioctl(struct drm_device *dev,
> struct drm_vgem_fence_attach *arg = data;
> struct vgem_file *vfile = file->driver_priv;
> struct reservation_object *resv;
> + struct drm_syncobj *sync = NULL;
> struct drm_gem_object *obj;
> struct dma_fence *fence;
> int ret;
>
> - if (arg->flags & ~VGEM_FENCE_WRITE)
> - return -EINVAL;
> -
> - if (arg->pad)
> + if (arg->flags & ~(VGEM_FENCE_WRITE | VGEM_FENCE_SYNCOBJ))
> return -EINVAL;
>
> obj = drm_gem_object_lookup(file, arg->handle);
> if (!obj)
> return -ENOENT;
>
> + if (arg->flags & VGEM_FENCE_SYNCOBJ) {
> + sync = drm_syncobj_find(file, arg->syncobj);
> + if (!sync) {
> + ret = -ENOENT;
> + goto err;
> + }
> +
> + /* We don't check if the current syncobj is busy or not, we
> + * will just replace it with ourselves.
> + */
> + }
> +
> ret = attach_dmabuf(dev, obj);
> if (ret)
> goto err;
> @@ -207,12 +219,18 @@ int vgem_fence_attach_ioctl(struct drm_device *dev,
> ret = 0;
> }
> }
> +
> + if (ret == 0 && sync)
> + drm_syncobj_replace_fence(sync, fence);
> +
> err_fence:
> if (ret) {
> dma_fence_signal(fence);
> dma_fence_put(fence);
> }
> err:
> + if (sync)
> + drm_syncobj_put(sync);
> drm_gem_object_unreference_unlocked(obj);
> return ret;
> }
> diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h
> index 89976da542b1..9010ab8343e5 100644
> --- a/include/drm/drm_syncobj.h
> +++ b/include/drm/drm_syncobj.h
> @@ -28,6 +28,8 @@
>
> #include "linux/dma-fence.h"
>
> +struct drm_file;
> +
> /**
> * struct drm_syncobj - sync object.
> *
> diff --git a/include/uapi/drm/vgem_drm.h b/include/uapi/drm/vgem_drm.h
> index bf66f5db6da8..94777197e561 100644
> --- a/include/uapi/drm/vgem_drm.h
> +++ b/include/uapi/drm/vgem_drm.h
> @@ -46,8 +46,9 @@ struct drm_vgem_fence_attach {
> __u32 handle;
> __u32 flags;
> #define VGEM_FENCE_WRITE 0x1
> +#define VGEM_FENCE_SYNCOBJ 0x2
> __u32 out_fence;
> - __u32 pad;
> + __u32 syncobj;
> };
>
> struct drm_vgem_fence_signal {
> --
> 2.13.3
>
>
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