diff mbox

[3/3] drm/vgem: Attach sw fences to exported vGEM dma-buf (ioctl)

Message ID 1468242488-1505-4-git-send-email-chris@chris-wilson.co.uk (mailing list archive)
State New, archived
Headers show

Commit Message

Chris Wilson July 11, 2016, 1:08 p.m. UTC
vGEM buffers are useful for passing data between software clients and
hardware renders. By allowing the user to create and attach fences to
the exported vGEM buffers (on the dma-buf), the user can implement a
deferred renderer and queue hardware operations like flipping and then
signal the buffer readiness (i.e. this allows the user to schedule
operations out-of-order, but have them complete in-order).

This also makes it much easier to write tightly controlled testcases for
dma-buf fencing and signaling between hardware drivers.

Testcase: igt/vgem_basic/dmabuf-fence
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Zach Reizner <zachr@google.com>
Cc: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Acked-by: Zach Reizner <zachr@google.com>
---
 drivers/gpu/drm/vgem/Makefile     |   2 +-
 drivers/gpu/drm/vgem/vgem_drv.c   |  34 ++++++
 drivers/gpu/drm/vgem/vgem_drv.h   |  18 ++++
 drivers/gpu/drm/vgem/vgem_fence.c | 220 ++++++++++++++++++++++++++++++++++++++
 include/uapi/drm/vgem_drm.h       |  62 +++++++++++
 5 files changed, 335 insertions(+), 1 deletion(-)
 create mode 100644 drivers/gpu/drm/vgem/vgem_fence.c
 create mode 100644 include/uapi/drm/vgem_drm.h

Comments

Gustavo Padovan July 11, 2016, 3:10 p.m. UTC | #1
2016-07-11 Chris Wilson <chris@chris-wilson.co.uk>:

> vGEM buffers are useful for passing data between software clients and
> hardware renders. By allowing the user to create and attach fences to
> the exported vGEM buffers (on the dma-buf), the user can implement a
> deferred renderer and queue hardware operations like flipping and then
> signal the buffer readiness (i.e. this allows the user to schedule
> operations out-of-order, but have them complete in-order).
> 
> This also makes it much easier to write tightly controlled testcases for
> dma-buf fencing and signaling between hardware drivers.
> 
> Testcase: igt/vgem_basic/dmabuf-fence
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Sean Paul <seanpaul@chromium.org>
> Cc: Zach Reizner <zachr@google.com>
> Cc: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> Acked-by: Zach Reizner <zachr@google.com>
> ---
>  drivers/gpu/drm/vgem/Makefile     |   2 +-
>  drivers/gpu/drm/vgem/vgem_drv.c   |  34 ++++++
>  drivers/gpu/drm/vgem/vgem_drv.h   |  18 ++++
>  drivers/gpu/drm/vgem/vgem_fence.c | 220 ++++++++++++++++++++++++++++++++++++++
>  include/uapi/drm/vgem_drm.h       |  62 +++++++++++
>  5 files changed, 335 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/gpu/drm/vgem/vgem_fence.c
>  create mode 100644 include/uapi/drm/vgem_drm.h
> 
> diff --git a/drivers/gpu/drm/vgem/Makefile b/drivers/gpu/drm/vgem/Makefile
> index 3f4c7b842028..bfcdea1330e6 100644
> --- a/drivers/gpu/drm/vgem/Makefile
> +++ b/drivers/gpu/drm/vgem/Makefile
> @@ -1,4 +1,4 @@
>  ccflags-y := -Iinclude/drm
> -vgem-y := vgem_drv.o
> +vgem-y := vgem_drv.o vgem_fence.o
>  
>  obj-$(CONFIG_DRM_VGEM)	+= vgem.o
> diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
> index b5fb968d2d5c..2659e5cda857 100644
> --- a/drivers/gpu/drm/vgem/vgem_drv.c
> +++ b/drivers/gpu/drm/vgem/vgem_drv.c
> @@ -83,6 +83,34 @@ static const struct vm_operations_struct vgem_gem_vm_ops = {
>  	.close = drm_gem_vm_close,
>  };
>  
> +static int vgem_open(struct drm_device *dev, struct drm_file *file)
> +{
> +	struct vgem_file *vfile;
> +	int ret;
> +
> +	vfile = kzalloc(sizeof(*vfile), GFP_KERNEL);
> +	if (!vfile)
> +		return -ENOMEM;
> +
> +	file->driver_priv = vfile;
> +
> +	ret = vgem_fence_open(vfile);
> +	if (ret) {
> +		kfree(vfile);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void vgem_preclose(struct drm_device *dev, struct drm_file *file)
> +{
> +	struct vgem_file *vfile = file->driver_priv;
> +
> +	vgem_fence_close(vfile);
> +	kfree(vfile);
> +}
> +
>  /* ioctls */
>  
>  static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
> @@ -164,6 +192,8 @@ unref:
>  }
>  
>  static struct drm_ioctl_desc vgem_ioctls[] = {
> +	DRM_IOCTL_DEF_DRV(VGEM_FENCE_ATTACH, vgem_fence_attach_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
> +	DRM_IOCTL_DEF_DRV(VGEM_FENCE_SIGNAL, vgem_fence_signal_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
>  };
>  
>  static int vgem_mmap(struct file *filp, struct vm_area_struct *vma)
> @@ -271,9 +301,12 @@ static int vgem_prime_mmap(struct drm_gem_object *obj,
>  
>  static struct drm_driver vgem_driver = {
>  	.driver_features		= DRIVER_GEM | DRIVER_PRIME,
> +	.open				= vgem_open,
> +	.preclose			= vgem_preclose,
>  	.gem_free_object_unlocked	= vgem_gem_free_object,
>  	.gem_vm_ops			= &vgem_gem_vm_ops,
>  	.ioctls				= vgem_ioctls,
> +	.num_ioctls 			= ARRAY_SIZE(vgem_ioctls),
>  	.fops				= &vgem_driver_fops,
>  
>  	.dumb_create			= vgem_gem_dumb_create,
> @@ -328,5 +361,6 @@ module_init(vgem_init);
>  module_exit(vgem_exit);
>  
>  MODULE_AUTHOR("Red Hat, Inc.");
> +MODULE_AUTHOR("Intel Corporation");
>  MODULE_DESCRIPTION(DRIVER_DESC);
>  MODULE_LICENSE("GPL and additional rights");
> diff --git a/drivers/gpu/drm/vgem/vgem_drv.h b/drivers/gpu/drm/vgem/vgem_drv.h
> index 988cbaae7588..88ce21010e28 100644
> --- a/drivers/gpu/drm/vgem/vgem_drv.h
> +++ b/drivers/gpu/drm/vgem/vgem_drv.h
> @@ -32,9 +32,27 @@
>  #include <drm/drmP.h>
>  #include <drm/drm_gem.h>
>  
> +#include <uapi/drm/vgem_drm.h>
> +
> +struct vgem_file {
> +	struct idr fence_idr;
> +	struct mutex fence_mutex;
> +	u64 fence_context;
> +	atomic_t fence_seqno;
> +};
> +
>  #define to_vgem_bo(x) container_of(x, struct drm_vgem_gem_object, base)
>  struct drm_vgem_gem_object {
>  	struct drm_gem_object base;
>  };
>  
> +int vgem_fence_open(struct vgem_file *file);
> +int vgem_fence_attach_ioctl(struct drm_device *dev,
> +			    void *data,
> +			    struct drm_file *file);
> +int vgem_fence_signal_ioctl(struct drm_device *dev,
> +			    void *data,
> +			    struct drm_file *file);
> +void vgem_fence_close(struct vgem_file *file);
> +
>  #endif
> diff --git a/drivers/gpu/drm/vgem/vgem_fence.c b/drivers/gpu/drm/vgem/vgem_fence.c
> new file mode 100644
> index 000000000000..649e9e1cee35
> --- /dev/null
> +++ b/drivers/gpu/drm/vgem/vgem_fence.c
> @@ -0,0 +1,220 @@
> +/*
> + * Copyright 2016 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software")
> + * to deal in the software without restriction, including without limitation
> + * on the rights to use, copy, modify, merge, publish, distribute, sub
> + * license, and/or sell copies of the Software, and to permit persons to whom
> + * them Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTIBILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES, OR OTHER LIABILITY, WHETHER
> + * IN AN ACTION OF CONTRACT, TORT, OR OTHERWISE, ARISING FROM, OUT OF OR IN
> + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
> + */
> +
> +#include <linux/dma-buf.h>
> +#include <linux/reservation.h>
> +
> +#include "vgem_drv.h"
> +
> +struct vgem_fence {
> +	struct fence base;
> +	struct spinlock lock;
> +};
> +
> +static const char *vgem_fence_get_driver_name(struct fence *fence)
> +{
> +	return "vgem";
> +}
> +
> +static const char *vgem_fence_get_timeline_name(struct fence *fence)
> +{
> +	return "file";
> +}
> +
> +static bool vgem_fence_signaled(struct fence *fence)
> +{
> +	return false;
> +}
> +
> +static bool vgem_fence_enable_signaling(struct fence *fence)
> +{
> +	return true;
> +}
> +
> +static void vgem_fence_value_str(struct fence *fence, char *str, int size)
> +{
> +	snprintf(str, size, "%u", fence->seqno);
> +}
> +
> +static void vgem_fence_timeline_value_str(struct fence *fence, char *str,
> +					  int size)
> +{
> +	snprintf(str, size, "%u", 0);
> +}

I think this would be mainly used for debug purposes but it would be
nice to actually return the current timeline value here, i.e., the
seqno of the last signalled fence.

This would also allow to return if the fence was signaled or not
in vgem_fence_signaled() instead of just return false. But if the
fence_put() after fence_signal() releases the last reference to
the fence vgem_fence_signaled() would be never be called after
it signalled.

> +
> +const struct fence_ops vgem_fence_ops = {
> +	.get_driver_name = vgem_fence_get_driver_name,
> +	.get_timeline_name = vgem_fence_get_timeline_name,
> +	.enable_signaling = vgem_fence_enable_signaling,
> +	.signaled = vgem_fence_signaled,
> +	.wait = fence_default_wait,
> +	.fence_value_str = vgem_fence_value_str,
> +	.timeline_value_str = vgem_fence_timeline_value_str,
> +};
> +
> +static u32 vgem_fence_next_seqno(struct vgem_file *vfile)
> +{
> +	u32 seqno;
> +
> +	seqno = atomic_inc_return(&vfile->fence_seqno);
> +	if (seqno == 0)
> +		seqno = atomic_inc_return(&vfile->fence_seqno);
> +
> +	return seqno;
> +}
> +
> +static struct fence *vgem_fence_create(struct vgem_file *vfile)
> +{
> +	struct vgem_fence *fence;
> +
> +	fence = kzalloc(sizeof(*fence), GFP_KERNEL);
> +	if (!fence)
> +		return NULL;
> +
> +	spin_lock_init(&fence->lock);
> +	fence_init(&fence->base,
> +		   &vgem_fence_ops,
> +		   &fence->lock,
> +		   vfile->fence_context,
> +		   vgem_fence_next_seqno(vfile));

Shall we make seqno u64 too?

	Gustavo
Chris Wilson July 11, 2016, 3:24 p.m. UTC | #2
On Mon, Jul 11, 2016 at 12:10:40PM -0300, Gustavo Padovan wrote:
> 2016-07-11 Chris Wilson <chris@chris-wilson.co.uk>:
> 
> > vGEM buffers are useful for passing data between software clients and
> > hardware renders. By allowing the user to create and attach fences to
> > the exported vGEM buffers (on the dma-buf), the user can implement a
> > deferred renderer and queue hardware operations like flipping and then
> > signal the buffer readiness (i.e. this allows the user to schedule
> > operations out-of-order, but have them complete in-order).
> > 
> > This also makes it much easier to write tightly controlled testcases for
> > dma-buf fencing and signaling between hardware drivers.
> > 
> > Testcase: igt/vgem_basic/dmabuf-fence
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Sean Paul <seanpaul@chromium.org>
> > Cc: Zach Reizner <zachr@google.com>
> > Cc: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> > Acked-by: Zach Reizner <zachr@google.com>
> > ---
> >  drivers/gpu/drm/vgem/Makefile     |   2 +-
> >  drivers/gpu/drm/vgem/vgem_drv.c   |  34 ++++++
> >  drivers/gpu/drm/vgem/vgem_drv.h   |  18 ++++
> >  drivers/gpu/drm/vgem/vgem_fence.c | 220 ++++++++++++++++++++++++++++++++++++++
> >  include/uapi/drm/vgem_drm.h       |  62 +++++++++++
> >  5 files changed, 335 insertions(+), 1 deletion(-)
> >  create mode 100644 drivers/gpu/drm/vgem/vgem_fence.c
> >  create mode 100644 include/uapi/drm/vgem_drm.h
> > 
> > diff --git a/drivers/gpu/drm/vgem/Makefile b/drivers/gpu/drm/vgem/Makefile
> > index 3f4c7b842028..bfcdea1330e6 100644
> > --- a/drivers/gpu/drm/vgem/Makefile
> > +++ b/drivers/gpu/drm/vgem/Makefile
> > @@ -1,4 +1,4 @@
> >  ccflags-y := -Iinclude/drm
> > -vgem-y := vgem_drv.o
> > +vgem-y := vgem_drv.o vgem_fence.o
> >  
> >  obj-$(CONFIG_DRM_VGEM)	+= vgem.o
> > diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
> > index b5fb968d2d5c..2659e5cda857 100644
> > --- a/drivers/gpu/drm/vgem/vgem_drv.c
> > +++ b/drivers/gpu/drm/vgem/vgem_drv.c
> > @@ -83,6 +83,34 @@ static const struct vm_operations_struct vgem_gem_vm_ops = {
> >  	.close = drm_gem_vm_close,
> >  };
> >  
> > +static int vgem_open(struct drm_device *dev, struct drm_file *file)
> > +{
> > +	struct vgem_file *vfile;
> > +	int ret;
> > +
> > +	vfile = kzalloc(sizeof(*vfile), GFP_KERNEL);
> > +	if (!vfile)
> > +		return -ENOMEM;
> > +
> > +	file->driver_priv = vfile;
> > +
> > +	ret = vgem_fence_open(vfile);
> > +	if (ret) {
> > +		kfree(vfile);
> > +		return ret;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static void vgem_preclose(struct drm_device *dev, struct drm_file *file)
> > +{
> > +	struct vgem_file *vfile = file->driver_priv;
> > +
> > +	vgem_fence_close(vfile);
> > +	kfree(vfile);
> > +}
> > +
> >  /* ioctls */
> >  
> >  static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
> > @@ -164,6 +192,8 @@ unref:
> >  }
> >  
> >  static struct drm_ioctl_desc vgem_ioctls[] = {
> > +	DRM_IOCTL_DEF_DRV(VGEM_FENCE_ATTACH, vgem_fence_attach_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
> > +	DRM_IOCTL_DEF_DRV(VGEM_FENCE_SIGNAL, vgem_fence_signal_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
> >  };
> >  
> >  static int vgem_mmap(struct file *filp, struct vm_area_struct *vma)
> > @@ -271,9 +301,12 @@ static int vgem_prime_mmap(struct drm_gem_object *obj,
> >  
> >  static struct drm_driver vgem_driver = {
> >  	.driver_features		= DRIVER_GEM | DRIVER_PRIME,
> > +	.open				= vgem_open,
> > +	.preclose			= vgem_preclose,
> >  	.gem_free_object_unlocked	= vgem_gem_free_object,
> >  	.gem_vm_ops			= &vgem_gem_vm_ops,
> >  	.ioctls				= vgem_ioctls,
> > +	.num_ioctls 			= ARRAY_SIZE(vgem_ioctls),
> >  	.fops				= &vgem_driver_fops,
> >  
> >  	.dumb_create			= vgem_gem_dumb_create,
> > @@ -328,5 +361,6 @@ module_init(vgem_init);
> >  module_exit(vgem_exit);
> >  
> >  MODULE_AUTHOR("Red Hat, Inc.");
> > +MODULE_AUTHOR("Intel Corporation");
> >  MODULE_DESCRIPTION(DRIVER_DESC);
> >  MODULE_LICENSE("GPL and additional rights");
> > diff --git a/drivers/gpu/drm/vgem/vgem_drv.h b/drivers/gpu/drm/vgem/vgem_drv.h
> > index 988cbaae7588..88ce21010e28 100644
> > --- a/drivers/gpu/drm/vgem/vgem_drv.h
> > +++ b/drivers/gpu/drm/vgem/vgem_drv.h
> > @@ -32,9 +32,27 @@
> >  #include <drm/drmP.h>
> >  #include <drm/drm_gem.h>
> >  
> > +#include <uapi/drm/vgem_drm.h>
> > +
> > +struct vgem_file {
> > +	struct idr fence_idr;
> > +	struct mutex fence_mutex;
> > +	u64 fence_context;
> > +	atomic_t fence_seqno;
> > +};
> > +
> >  #define to_vgem_bo(x) container_of(x, struct drm_vgem_gem_object, base)
> >  struct drm_vgem_gem_object {
> >  	struct drm_gem_object base;
> >  };
> >  
> > +int vgem_fence_open(struct vgem_file *file);
> > +int vgem_fence_attach_ioctl(struct drm_device *dev,
> > +			    void *data,
> > +			    struct drm_file *file);
> > +int vgem_fence_signal_ioctl(struct drm_device *dev,
> > +			    void *data,
> > +			    struct drm_file *file);
> > +void vgem_fence_close(struct vgem_file *file);
> > +
> >  #endif
> > diff --git a/drivers/gpu/drm/vgem/vgem_fence.c b/drivers/gpu/drm/vgem/vgem_fence.c
> > new file mode 100644
> > index 000000000000..649e9e1cee35
> > --- /dev/null
> > +++ b/drivers/gpu/drm/vgem/vgem_fence.c
> > @@ -0,0 +1,220 @@
> > +/*
> > + * Copyright 2016 Intel Corporation
> > + *
> > + * Permission is hereby granted, free of charge, to any person obtaining a
> > + * copy of this software and associated documentation files (the "Software")
> > + * to deal in the software without restriction, including without limitation
> > + * on the rights to use, copy, modify, merge, publish, distribute, sub
> > + * license, and/or sell copies of the Software, and to permit persons to whom
> > + * them Software is furnished to do so, subject to the following conditions:
> > + *
> > + * The above copyright notice and this permission notice (including the next
> > + * paragraph) shall be included in all copies or substantial portions of the
> > + * Software.
> > + *
> > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTIBILITY,
> > + * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.  IN NO EVENT SHALL
> > + * THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES, OR OTHER LIABILITY, WHETHER
> > + * IN AN ACTION OF CONTRACT, TORT, OR OTHERWISE, ARISING FROM, OUT OF OR IN
> > + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
> > + */
> > +
> > +#include <linux/dma-buf.h>
> > +#include <linux/reservation.h>
> > +
> > +#include "vgem_drv.h"
> > +
> > +struct vgem_fence {
> > +	struct fence base;
> > +	struct spinlock lock;
> > +};
> > +
> > +static const char *vgem_fence_get_driver_name(struct fence *fence)
> > +{
> > +	return "vgem";
> > +}
> > +
> > +static const char *vgem_fence_get_timeline_name(struct fence *fence)
> > +{
> > +	return "file";
> > +}
> > +
> > +static bool vgem_fence_signaled(struct fence *fence)
> > +{
> > +	return false;
> > +}
> > +
> > +static bool vgem_fence_enable_signaling(struct fence *fence)
> > +{
> > +	return true;
> > +}
> > +
> > +static void vgem_fence_value_str(struct fence *fence, char *str, int size)
> > +{
> > +	snprintf(str, size, "%u", fence->seqno);
> > +}
> > +
> > +static void vgem_fence_timeline_value_str(struct fence *fence, char *str,
> > +					  int size)
> > +{
> > +	snprintf(str, size, "%u", 0);
> > +}
> 
> I think this would be mainly used for debug purposes but it would be
> nice to actually return the current timeline value here, i.e., the
> seqno of the last signalled fence.

The fences can and will be signaled in any order, there is no timeline
here under the control of userspace, we only give them fences.
 
> This would also allow to return if the fence was signaled or not
> in vgem_fence_signaled() instead of just return false.

That doesn't fit the out-of-order unbound nature of the interface. The
interface is just a collection of fences that userspace associates with
the buffer that it may signal at any time. (Having no strict timeline is
an advantage!)
-Chris
Daniel Vetter July 12, 2016, 10:44 a.m. UTC | #3
On Mon, Jul 11, 2016 at 04:24:45PM +0100, Chris Wilson wrote:
> On Mon, Jul 11, 2016 at 12:10:40PM -0300, Gustavo Padovan wrote:
> > 2016-07-11 Chris Wilson <chris@chris-wilson.co.uk>:
> > 
> > > vGEM buffers are useful for passing data between software clients and
> > > hardware renders. By allowing the user to create and attach fences to
> > > the exported vGEM buffers (on the dma-buf), the user can implement a
> > > deferred renderer and queue hardware operations like flipping and then
> > > signal the buffer readiness (i.e. this allows the user to schedule
> > > operations out-of-order, but have them complete in-order).
> > > 
> > > This also makes it much easier to write tightly controlled testcases for
> > > dma-buf fencing and signaling between hardware drivers.
> > > 
> > > Testcase: igt/vgem_basic/dmabuf-fence
> > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > > Cc: Sean Paul <seanpaul@chromium.org>
> > > Cc: Zach Reizner <zachr@google.com>
> > > Cc: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> > > Acked-by: Zach Reizner <zachr@google.com>
> > > ---
> > >  drivers/gpu/drm/vgem/Makefile     |   2 +-
> > >  drivers/gpu/drm/vgem/vgem_drv.c   |  34 ++++++
> > >  drivers/gpu/drm/vgem/vgem_drv.h   |  18 ++++
> > >  drivers/gpu/drm/vgem/vgem_fence.c | 220 ++++++++++++++++++++++++++++++++++++++
> > >  include/uapi/drm/vgem_drm.h       |  62 +++++++++++
> > >  5 files changed, 335 insertions(+), 1 deletion(-)
> > >  create mode 100644 drivers/gpu/drm/vgem/vgem_fence.c
> > >  create mode 100644 include/uapi/drm/vgem_drm.h
> > > 
> > > diff --git a/drivers/gpu/drm/vgem/Makefile b/drivers/gpu/drm/vgem/Makefile
> > > index 3f4c7b842028..bfcdea1330e6 100644
> > > --- a/drivers/gpu/drm/vgem/Makefile
> > > +++ b/drivers/gpu/drm/vgem/Makefile
> > > @@ -1,4 +1,4 @@
> > >  ccflags-y := -Iinclude/drm
> > > -vgem-y := vgem_drv.o
> > > +vgem-y := vgem_drv.o vgem_fence.o
> > >  
> > >  obj-$(CONFIG_DRM_VGEM)	+= vgem.o
> > > diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
> > > index b5fb968d2d5c..2659e5cda857 100644
> > > --- a/drivers/gpu/drm/vgem/vgem_drv.c
> > > +++ b/drivers/gpu/drm/vgem/vgem_drv.c
> > > @@ -83,6 +83,34 @@ static const struct vm_operations_struct vgem_gem_vm_ops = {
> > >  	.close = drm_gem_vm_close,
> > >  };
> > >  
> > > +static int vgem_open(struct drm_device *dev, struct drm_file *file)
> > > +{
> > > +	struct vgem_file *vfile;
> > > +	int ret;
> > > +
> > > +	vfile = kzalloc(sizeof(*vfile), GFP_KERNEL);
> > > +	if (!vfile)
> > > +		return -ENOMEM;
> > > +
> > > +	file->driver_priv = vfile;
> > > +
> > > +	ret = vgem_fence_open(vfile);
> > > +	if (ret) {
> > > +		kfree(vfile);
> > > +		return ret;
> > > +	}
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static void vgem_preclose(struct drm_device *dev, struct drm_file *file)
> > > +{
> > > +	struct vgem_file *vfile = file->driver_priv;
> > > +
> > > +	vgem_fence_close(vfile);
> > > +	kfree(vfile);
> > > +}
> > > +
> > >  /* ioctls */
> > >  
> > >  static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
> > > @@ -164,6 +192,8 @@ unref:
> > >  }
> > >  
> > >  static struct drm_ioctl_desc vgem_ioctls[] = {
> > > +	DRM_IOCTL_DEF_DRV(VGEM_FENCE_ATTACH, vgem_fence_attach_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
> > > +	DRM_IOCTL_DEF_DRV(VGEM_FENCE_SIGNAL, vgem_fence_signal_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
> > >  };
> > >  
> > >  static int vgem_mmap(struct file *filp, struct vm_area_struct *vma)
> > > @@ -271,9 +301,12 @@ static int vgem_prime_mmap(struct drm_gem_object *obj,
> > >  
> > >  static struct drm_driver vgem_driver = {
> > >  	.driver_features		= DRIVER_GEM | DRIVER_PRIME,
> > > +	.open				= vgem_open,
> > > +	.preclose			= vgem_preclose,
> > >  	.gem_free_object_unlocked	= vgem_gem_free_object,
> > >  	.gem_vm_ops			= &vgem_gem_vm_ops,
> > >  	.ioctls				= vgem_ioctls,
> > > +	.num_ioctls 			= ARRAY_SIZE(vgem_ioctls),
> > >  	.fops				= &vgem_driver_fops,
> > >  
> > >  	.dumb_create			= vgem_gem_dumb_create,
> > > @@ -328,5 +361,6 @@ module_init(vgem_init);
> > >  module_exit(vgem_exit);
> > >  
> > >  MODULE_AUTHOR("Red Hat, Inc.");
> > > +MODULE_AUTHOR("Intel Corporation");
> > >  MODULE_DESCRIPTION(DRIVER_DESC);
> > >  MODULE_LICENSE("GPL and additional rights");
> > > diff --git a/drivers/gpu/drm/vgem/vgem_drv.h b/drivers/gpu/drm/vgem/vgem_drv.h
> > > index 988cbaae7588..88ce21010e28 100644
> > > --- a/drivers/gpu/drm/vgem/vgem_drv.h
> > > +++ b/drivers/gpu/drm/vgem/vgem_drv.h
> > > @@ -32,9 +32,27 @@
> > >  #include <drm/drmP.h>
> > >  #include <drm/drm_gem.h>
> > >  
> > > +#include <uapi/drm/vgem_drm.h>
> > > +
> > > +struct vgem_file {
> > > +	struct idr fence_idr;
> > > +	struct mutex fence_mutex;
> > > +	u64 fence_context;
> > > +	atomic_t fence_seqno;
> > > +};
> > > +
> > >  #define to_vgem_bo(x) container_of(x, struct drm_vgem_gem_object, base)
> > >  struct drm_vgem_gem_object {
> > >  	struct drm_gem_object base;
> > >  };
> > >  
> > > +int vgem_fence_open(struct vgem_file *file);
> > > +int vgem_fence_attach_ioctl(struct drm_device *dev,
> > > +			    void *data,
> > > +			    struct drm_file *file);
> > > +int vgem_fence_signal_ioctl(struct drm_device *dev,
> > > +			    void *data,
> > > +			    struct drm_file *file);
> > > +void vgem_fence_close(struct vgem_file *file);
> > > +
> > >  #endif
> > > diff --git a/drivers/gpu/drm/vgem/vgem_fence.c b/drivers/gpu/drm/vgem/vgem_fence.c
> > > new file mode 100644
> > > index 000000000000..649e9e1cee35
> > > --- /dev/null
> > > +++ b/drivers/gpu/drm/vgem/vgem_fence.c
> > > @@ -0,0 +1,220 @@
> > > +/*
> > > + * Copyright 2016 Intel Corporation
> > > + *
> > > + * Permission is hereby granted, free of charge, to any person obtaining a
> > > + * copy of this software and associated documentation files (the "Software")
> > > + * to deal in the software without restriction, including without limitation
> > > + * on the rights to use, copy, modify, merge, publish, distribute, sub
> > > + * license, and/or sell copies of the Software, and to permit persons to whom
> > > + * them Software is furnished to do so, subject to the following conditions:
> > > + *
> > > + * The above copyright notice and this permission notice (including the next
> > > + * paragraph) shall be included in all copies or substantial portions of the
> > > + * Software.
> > > + *
> > > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> > > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTIBILITY,
> > > + * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.  IN NO EVENT SHALL
> > > + * THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES, OR OTHER LIABILITY, WHETHER
> > > + * IN AN ACTION OF CONTRACT, TORT, OR OTHERWISE, ARISING FROM, OUT OF OR IN
> > > + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
> > > + */
> > > +
> > > +#include <linux/dma-buf.h>
> > > +#include <linux/reservation.h>
> > > +
> > > +#include "vgem_drv.h"
> > > +
> > > +struct vgem_fence {
> > > +	struct fence base;
> > > +	struct spinlock lock;
> > > +};
> > > +
> > > +static const char *vgem_fence_get_driver_name(struct fence *fence)
> > > +{
> > > +	return "vgem";
> > > +}
> > > +
> > > +static const char *vgem_fence_get_timeline_name(struct fence *fence)
> > > +{
> > > +	return "file";
> > > +}
> > > +
> > > +static bool vgem_fence_signaled(struct fence *fence)
> > > +{
> > > +	return false;
> > > +}
> > > +
> > > +static bool vgem_fence_enable_signaling(struct fence *fence)
> > > +{
> > > +	return true;
> > > +}
> > > +
> > > +static void vgem_fence_value_str(struct fence *fence, char *str, int size)
> > > +{
> > > +	snprintf(str, size, "%u", fence->seqno);
> > > +}
> > > +
> > > +static void vgem_fence_timeline_value_str(struct fence *fence, char *str,
> > > +					  int size)
> > > +{
> > > +	snprintf(str, size, "%u", 0);
> > > +}
> > 
> > I think this would be mainly used for debug purposes but it would be
> > nice to actually return the current timeline value here, i.e., the
> > seqno of the last signalled fence.
> 
> The fences can and will be signaled in any order, there is no timeline
> here under the control of userspace, we only give them fences.
>  
> > This would also allow to return if the fence was signaled or not
> > in vgem_fence_signaled() instead of just return false.
> 
> That doesn't fit the out-of-order unbound nature of the interface. The
> interface is just a collection of fences that userspace associates with
> the buffer that it may signal at any time. (Having no strict timeline is
> an advantage!)

Fences on the same timeline are supposed to be signalled in-order. If you
want full out-of-order fences then you need to grab a new timeline number
for each one. Drivers can and do merge fences on the same timeline and
just carry the one with the largest seqno around.
-Daniel
Chris Wilson July 12, 2016, 11:04 a.m. UTC | #4
On Tue, Jul 12, 2016 at 12:44:17PM +0200, Daniel Vetter wrote:
> On Mon, Jul 11, 2016 at 04:24:45PM +0100, Chris Wilson wrote:
> > That doesn't fit the out-of-order unbound nature of the interface. The
> > interface is just a collection of fences that userspace associates with
> > the buffer that it may signal at any time. (Having no strict timeline is
> > an advantage!)
> 
> Fences on the same timeline are supposed to be signalled in-order. If you
> want full out-of-order fences then you need to grab a new timeline number
> for each one. Drivers can and do merge fences on the same timeline and
> just carry the one with the largest seqno around.

Ugh. Timelines simply don't mean anything everywhere - a very leaky
abstration.

Nevertheless, a fence_context per vgem_fence would do the trick.
-Chris
Daniel Vetter July 12, 2016, 2:23 p.m. UTC | #5
On Tue, Jul 12, 2016 at 12:04:03PM +0100, Chris Wilson wrote:
> On Tue, Jul 12, 2016 at 12:44:17PM +0200, Daniel Vetter wrote:
> > On Mon, Jul 11, 2016 at 04:24:45PM +0100, Chris Wilson wrote:
> > > That doesn't fit the out-of-order unbound nature of the interface. The
> > > interface is just a collection of fences that userspace associates with
> > > the buffer that it may signal at any time. (Having no strict timeline is
> > > an advantage!)
> > 
> > Fences on the same timeline are supposed to be signalled in-order. If you
> > want full out-of-order fences then you need to grab a new timeline number
> > for each one. Drivers can and do merge fences on the same timeline and
> > just carry the one with the largest seqno around.
> 
> Ugh. Timelines simply don't mean anything everywhere - a very leaky
> abstration.
> 
> Nevertheless, a fence_context per vgem_fence would do the trick.

Yeah it's a bit meh, but allocating plenty of them is how we currently
cope with it. I suggested that we have a special FENCE_TIMELINE_UNORDERED
flag (we need it for fence_array too), but that wasn't popular. I still
expect it to happen eventually ;-)
-Daniel
diff mbox

Patch

diff --git a/drivers/gpu/drm/vgem/Makefile b/drivers/gpu/drm/vgem/Makefile
index 3f4c7b842028..bfcdea1330e6 100644
--- a/drivers/gpu/drm/vgem/Makefile
+++ b/drivers/gpu/drm/vgem/Makefile
@@ -1,4 +1,4 @@ 
 ccflags-y := -Iinclude/drm
-vgem-y := vgem_drv.o
+vgem-y := vgem_drv.o vgem_fence.o
 
 obj-$(CONFIG_DRM_VGEM)	+= vgem.o
diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index b5fb968d2d5c..2659e5cda857 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -83,6 +83,34 @@  static const struct vm_operations_struct vgem_gem_vm_ops = {
 	.close = drm_gem_vm_close,
 };
 
+static int vgem_open(struct drm_device *dev, struct drm_file *file)
+{
+	struct vgem_file *vfile;
+	int ret;
+
+	vfile = kzalloc(sizeof(*vfile), GFP_KERNEL);
+	if (!vfile)
+		return -ENOMEM;
+
+	file->driver_priv = vfile;
+
+	ret = vgem_fence_open(vfile);
+	if (ret) {
+		kfree(vfile);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void vgem_preclose(struct drm_device *dev, struct drm_file *file)
+{
+	struct vgem_file *vfile = file->driver_priv;
+
+	vgem_fence_close(vfile);
+	kfree(vfile);
+}
+
 /* ioctls */
 
 static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
@@ -164,6 +192,8 @@  unref:
 }
 
 static struct drm_ioctl_desc vgem_ioctls[] = {
+	DRM_IOCTL_DEF_DRV(VGEM_FENCE_ATTACH, vgem_fence_attach_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF_DRV(VGEM_FENCE_SIGNAL, vgem_fence_signal_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
 };
 
 static int vgem_mmap(struct file *filp, struct vm_area_struct *vma)
@@ -271,9 +301,12 @@  static int vgem_prime_mmap(struct drm_gem_object *obj,
 
 static struct drm_driver vgem_driver = {
 	.driver_features		= DRIVER_GEM | DRIVER_PRIME,
+	.open				= vgem_open,
+	.preclose			= vgem_preclose,
 	.gem_free_object_unlocked	= vgem_gem_free_object,
 	.gem_vm_ops			= &vgem_gem_vm_ops,
 	.ioctls				= vgem_ioctls,
+	.num_ioctls 			= ARRAY_SIZE(vgem_ioctls),
 	.fops				= &vgem_driver_fops,
 
 	.dumb_create			= vgem_gem_dumb_create,
@@ -328,5 +361,6 @@  module_init(vgem_init);
 module_exit(vgem_exit);
 
 MODULE_AUTHOR("Red Hat, Inc.");
+MODULE_AUTHOR("Intel Corporation");
 MODULE_DESCRIPTION(DRIVER_DESC);
 MODULE_LICENSE("GPL and additional rights");
diff --git a/drivers/gpu/drm/vgem/vgem_drv.h b/drivers/gpu/drm/vgem/vgem_drv.h
index 988cbaae7588..88ce21010e28 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.h
+++ b/drivers/gpu/drm/vgem/vgem_drv.h
@@ -32,9 +32,27 @@ 
 #include <drm/drmP.h>
 #include <drm/drm_gem.h>
 
+#include <uapi/drm/vgem_drm.h>
+
+struct vgem_file {
+	struct idr fence_idr;
+	struct mutex fence_mutex;
+	u64 fence_context;
+	atomic_t fence_seqno;
+};
+
 #define to_vgem_bo(x) container_of(x, struct drm_vgem_gem_object, base)
 struct drm_vgem_gem_object {
 	struct drm_gem_object base;
 };
 
+int vgem_fence_open(struct vgem_file *file);
+int vgem_fence_attach_ioctl(struct drm_device *dev,
+			    void *data,
+			    struct drm_file *file);
+int vgem_fence_signal_ioctl(struct drm_device *dev,
+			    void *data,
+			    struct drm_file *file);
+void vgem_fence_close(struct vgem_file *file);
+
 #endif
diff --git a/drivers/gpu/drm/vgem/vgem_fence.c b/drivers/gpu/drm/vgem/vgem_fence.c
new file mode 100644
index 000000000000..649e9e1cee35
--- /dev/null
+++ b/drivers/gpu/drm/vgem/vgem_fence.c
@@ -0,0 +1,220 @@ 
+/*
+ * Copyright 2016 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software")
+ * to deal in the software without restriction, including without limitation
+ * on the rights to use, copy, modify, merge, publish, distribute, sub
+ * license, and/or sell copies of the Software, and to permit persons to whom
+ * them Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTIBILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES, OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT, OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <linux/dma-buf.h>
+#include <linux/reservation.h>
+
+#include "vgem_drv.h"
+
+struct vgem_fence {
+	struct fence base;
+	struct spinlock lock;
+};
+
+static const char *vgem_fence_get_driver_name(struct fence *fence)
+{
+	return "vgem";
+}
+
+static const char *vgem_fence_get_timeline_name(struct fence *fence)
+{
+	return "file";
+}
+
+static bool vgem_fence_signaled(struct fence *fence)
+{
+	return false;
+}
+
+static bool vgem_fence_enable_signaling(struct fence *fence)
+{
+	return true;
+}
+
+static void vgem_fence_value_str(struct fence *fence, char *str, int size)
+{
+	snprintf(str, size, "%u", fence->seqno);
+}
+
+static void vgem_fence_timeline_value_str(struct fence *fence, char *str,
+					  int size)
+{
+	snprintf(str, size, "%u", 0);
+}
+
+const struct fence_ops vgem_fence_ops = {
+	.get_driver_name = vgem_fence_get_driver_name,
+	.get_timeline_name = vgem_fence_get_timeline_name,
+	.enable_signaling = vgem_fence_enable_signaling,
+	.signaled = vgem_fence_signaled,
+	.wait = fence_default_wait,
+	.fence_value_str = vgem_fence_value_str,
+	.timeline_value_str = vgem_fence_timeline_value_str,
+};
+
+static u32 vgem_fence_next_seqno(struct vgem_file *vfile)
+{
+	u32 seqno;
+
+	seqno = atomic_inc_return(&vfile->fence_seqno);
+	if (seqno == 0)
+		seqno = atomic_inc_return(&vfile->fence_seqno);
+
+	return seqno;
+}
+
+static struct fence *vgem_fence_create(struct vgem_file *vfile)
+{
+	struct vgem_fence *fence;
+
+	fence = kzalloc(sizeof(*fence), GFP_KERNEL);
+	if (!fence)
+		return NULL;
+
+	spin_lock_init(&fence->lock);
+	fence_init(&fence->base,
+		   &vgem_fence_ops,
+		   &fence->lock,
+		   vfile->fence_context,
+		   vgem_fence_next_seqno(vfile));
+
+	return &fence->base;
+}
+
+static int attach_dmabuf(struct drm_device *dev,
+			 struct drm_gem_object *obj)
+{
+	struct dma_buf *dmabuf;
+
+	if (obj->dma_buf)
+		return 0;
+
+	dmabuf = dev->driver->gem_prime_export(dev, obj, 0);
+	if (IS_ERR(dmabuf))
+		return PTR_ERR(dmabuf);
+
+	obj->dma_buf = dmabuf;
+	drm_gem_object_reference(obj);
+	return 0;
+}
+
+int vgem_fence_attach_ioctl(struct drm_device *dev,
+			    void *data,
+			    struct drm_file *file)
+{
+	struct drm_vgem_fence_attach *arg = data;
+	struct vgem_file *vfile = file->driver_priv;
+	struct reservation_object *resv;
+	struct drm_gem_object *obj;
+	struct fence *fence;
+	int ret;
+
+	if (arg->flags & ~VGEM_FENCE_WRITE)
+		return -EINVAL;
+
+	if (arg->pad)
+		return -EINVAL;
+
+	obj = drm_gem_object_lookup(file, arg->handle);
+	if (!obj)
+		return -ENOENT;
+
+	ret = attach_dmabuf(dev, obj);
+	if (ret)
+		goto out;
+
+	fence = vgem_fence_create(vfile);
+	if (!fence) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ret = 0;
+	resv = obj->dma_buf->resv;
+	mutex_lock(&resv->lock.base);
+	if (arg->flags & VGEM_FENCE_WRITE)
+		reservation_object_add_excl_fence(resv, fence);
+	else if ((ret = reservation_object_reserve_shared(resv)) == 0)
+		reservation_object_add_shared_fence(resv, fence);
+	mutex_unlock(&resv->lock.base);
+
+	if (ret == 0) {
+		mutex_lock(&vfile->fence_mutex);
+		ret = idr_alloc(&vfile->fence_idr, fence, 1, 0, GFP_KERNEL);
+		mutex_unlock(&vfile->fence_mutex);
+		if (ret > 0) {
+			arg->out_fence = ret;
+			ret = 0;
+		}
+	}
+	if (ret)
+		fence_put(fence);
+out:
+	drm_gem_object_unreference_unlocked(obj);
+	return ret;
+}
+
+int vgem_fence_signal_ioctl(struct drm_device *dev,
+			    void *data,
+			    struct drm_file *file)
+{
+	struct vgem_file *vfile = file->driver_priv;
+	struct drm_vgem_fence_signal *arg = data;
+	struct fence *fence;
+
+	if (arg->flags)
+		return -EINVAL;
+
+	mutex_lock(&vfile->fence_mutex);
+	fence = idr_replace(&vfile->fence_idr, NULL, arg->fence);
+	mutex_unlock(&vfile->fence_mutex);
+	if (!fence)
+		return -ENOENT;
+	if (IS_ERR(fence))
+		return PTR_ERR(fence);
+
+	fence_signal(fence);
+	fence_put(fence);
+	return 0;
+}
+
+int vgem_fence_open(struct vgem_file *vfile)
+{
+	mutex_init(&vfile->fence_mutex);
+	idr_init(&vfile->fence_idr);
+	vfile->fence_context = fence_context_alloc(1);
+
+	return 0;
+}
+
+static int __vgem_fence_idr_fini(int id, void *p, void *data)
+{
+	fence_signal(p);
+	fence_put(p);
+	return 0;
+}
+
+void vgem_fence_close(struct vgem_file *vfile)
+{
+	idr_for_each(&vfile->fence_idr, __vgem_fence_idr_fini, vfile);
+	idr_destroy(&vfile->fence_idr);
+}
diff --git a/include/uapi/drm/vgem_drm.h b/include/uapi/drm/vgem_drm.h
new file mode 100644
index 000000000000..352d2fae8de9
--- /dev/null
+++ b/include/uapi/drm/vgem_drm.h
@@ -0,0 +1,62 @@ 
+/*
+ * Copyright 2016 Intel Corporation
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ */
+
+#ifndef _UAPI_VGEM_DRM_H_
+#define _UAPI_VGEM_DRM_H_
+
+#include "drm.h"
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+/* Please note that modifications to all structs defined here are
+ * subject to backwards-compatibility constraints.
+ */
+#define DRM_VGEM_FENCE_ATTACH	0x1
+#define DRM_VGEM_FENCE_SIGNAL	0x2
+
+#define DRM_IOCTL_VGEM_FENCE_ATTACH	DRM_IOWR( DRM_COMMAND_BASE + DRM_VGEM_FENCE_ATTACH, struct drm_vgem_fence_attach)
+#define DRM_IOCTL_VGEM_FENCE_SIGNAL	DRM_IOW( DRM_COMMAND_BASE + DRM_VGEM_FENCE_SIGNAL, struct drm_vgem_fence_signal)
+
+struct drm_vgem_fence_attach {
+	__u32 handle;
+	__u32 flags;
+#define VGEM_FENCE_WRITE 0x1
+	__u32 out_fence;
+	__u32 pad;
+};
+
+struct drm_vgem_fence_signal {
+	__u32 fence;
+	__u32 flags;
+};
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif /* _UAPI_VGEM_DRM_H_ */