[v7,05/15] dma-buf/sync_file: Add SET_DEADLINE ioctl

From: Rob Clark <robdclark@chromium.org>

The initial purpose is for igt tests, but this would also be useful for
compositors that wait until close to vblank deadline to make decisions
about which frame to show.

The igt tests can be found at:

https://gitlab.freedesktop.org/robclark/igt-gpu-tools/-/commits/fence-deadline

v2: Clarify the timebase, add link to igt tests
v3: Use u64 value in ns to express deadline.
v4: More doc

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 drivers/dma-buf/dma-fence.c    |  3 ++-
 drivers/dma-buf/sync_file.c    | 19 +++++++++++++++++++
 include/uapi/linux/sync_file.h | 22 ++++++++++++++++++++++
 3 files changed, 43 insertions(+), 1 deletion(-)

On Mon, 27 Feb 2023 11:35:11 -0800
Rob Clark <robdclark@gmail.com> wrote:

> From: Rob Clark <robdclark@chromium.org>
> 
> The initial purpose is for igt tests, but this would also be useful for
> compositors that wait until close to vblank deadline to make decisions
> about which frame to show.
> 
> The igt tests can be found at:
> 
> https://gitlab.freedesktop.org/robclark/igt-gpu-tools/-/commits/fence-deadline
> 
> v2: Clarify the timebase, add link to igt tests
> v3: Use u64 value in ns to express deadline.
> v4: More doc
> 
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
>  drivers/dma-buf/dma-fence.c    |  3 ++-
>  drivers/dma-buf/sync_file.c    | 19 +++++++++++++++++++
>  include/uapi/linux/sync_file.h | 22 ++++++++++++++++++++++
>  3 files changed, 43 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
> index e103e821d993..7761ceeae620 100644
> --- a/drivers/dma-buf/dma-fence.c
> +++ b/drivers/dma-buf/dma-fence.c
> @@ -933,7 +933,8 @@ EXPORT_SYMBOL(dma_fence_wait_any_timeout);
>   *   the GPU's devfreq to reduce frequency, when in fact the opposite is what is
>   *   needed.
>   *
> - * To this end, deadline hint(s) can be set on a &dma_fence via &dma_fence_set_deadline.
> + * To this end, deadline hint(s) can be set on a &dma_fence via &dma_fence_set_deadline
> + * (or indirectly via userspace facing ioctls like &SYNC_IOC_SET_DEADLINE).
>   * The deadline hint provides a way for the waiting driver, or userspace, to
>   * convey an appropriate sense of urgency to the signaling driver.

Hi,

when the kernel HTML doc is generated, I assume the above becomes a
link to "DOC: SYNC_IOC_SET_DEADLINE - set a deadline on a fence", right?

>   *
> diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
> index af57799c86ce..418021cfb87c 100644
> --- a/drivers/dma-buf/sync_file.c
> +++ b/drivers/dma-buf/sync_file.c
> @@ -350,6 +350,22 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
>  	return ret;
>  }
>  
> +static int sync_file_ioctl_set_deadline(struct sync_file *sync_file,
> +					unsigned long arg)
> +{
> +	struct sync_set_deadline ts;
> +
> +	if (copy_from_user(&ts, (void __user *)arg, sizeof(ts)))
> +		return -EFAULT;
> +
> +	if (ts.pad)
> +		return -EINVAL;
> +
> +	dma_fence_set_deadline(sync_file->fence, ns_to_ktime(ts.deadline_ns));
> +
> +	return 0;
> +}
> +
>  static long sync_file_ioctl(struct file *file, unsigned int cmd,
>  			    unsigned long arg)
>  {
> @@ -362,6 +378,9 @@ static long sync_file_ioctl(struct file *file, unsigned int cmd,
>  	case SYNC_IOC_FILE_INFO:
>  		return sync_file_ioctl_fence_info(sync_file, arg);
>  
> +	case SYNC_IOC_SET_DEADLINE:
> +		return sync_file_ioctl_set_deadline(sync_file, arg);
> +
>  	default:
>  		return -ENOTTY;
>  	}
> diff --git a/include/uapi/linux/sync_file.h b/include/uapi/linux/sync_file.h
> index ee2dcfb3d660..49325cf6749b 100644
> --- a/include/uapi/linux/sync_file.h
> +++ b/include/uapi/linux/sync_file.h
> @@ -67,6 +67,21 @@ struct sync_file_info {
>  	__u64	sync_fence_info;
>  };
>  
> +/**
> + * struct sync_set_deadline - set a deadline hint on a fence
> + * @deadline_ns: absolute time of the deadline

Is it legal to pass zero as deadline_ns?

> + * @pad:	must be zero
> + *
> + * The timebase for the deadline is CLOCK_MONOTONIC (same as vblank)

Does something here provide doc links to "DOC: SYNC_IOC_SET_DEADLINE -
set a deadline on a fence" and to the "DOC: deadline hints"?

> + */
> +struct sync_set_deadline {
> +	__u64	deadline_ns;
> +	/* Not strictly needed for alignment but gives some possibility
> +	 * for future extension:
> +	 */
> +	__u64	pad;
> +};
> +
>  #define SYNC_IOC_MAGIC		'>'
>  
>  /**
> @@ -95,4 +110,11 @@ struct sync_file_info {
>   */
>  #define SYNC_IOC_FILE_INFO	_IOWR(SYNC_IOC_MAGIC, 4, struct sync_file_info)
>  
> +/**
> + * DOC: SYNC_IOC_SET_DEADLINE - set a deadline on a fence
> + *
> + * Allows userspace to set a deadline on a fence, see dma_fence_set_deadline()

Does something here provide doc links to struct sync_set_deadline and
to the "DOC: deadline hints"?

> + */
> +#define SYNC_IOC_SET_DEADLINE	_IOW(SYNC_IOC_MAGIC, 5, struct sync_set_deadline)
> +
>  #endif /* _UAPI_LINUX_SYNC_H */

With all those links added:
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>


Thanks,
pq

On Tue, Feb 28, 2023 at 1:22 AM Pekka Paalanen <ppaalanen@gmail.com> wrote:
>
> On Mon, 27 Feb 2023 11:35:11 -0800
> Rob Clark <robdclark@gmail.com> wrote:
>
> > From: Rob Clark <robdclark@chromium.org>
> >
> > The initial purpose is for igt tests, but this would also be useful for
> > compositors that wait until close to vblank deadline to make decisions
> > about which frame to show.
> >
> > The igt tests can be found at:
> >
> > https://gitlab.freedesktop.org/robclark/igt-gpu-tools/-/commits/fence-deadline
> >
> > v2: Clarify the timebase, add link to igt tests
> > v3: Use u64 value in ns to express deadline.
> > v4: More doc
> >
> > Signed-off-by: Rob Clark <robdclark@chromium.org>
> > ---
> >  drivers/dma-buf/dma-fence.c    |  3 ++-
> >  drivers/dma-buf/sync_file.c    | 19 +++++++++++++++++++
> >  include/uapi/linux/sync_file.h | 22 ++++++++++++++++++++++
> >  3 files changed, 43 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
> > index e103e821d993..7761ceeae620 100644
> > --- a/drivers/dma-buf/dma-fence.c
> > +++ b/drivers/dma-buf/dma-fence.c
> > @@ -933,7 +933,8 @@ EXPORT_SYMBOL(dma_fence_wait_any_timeout);
> >   *   the GPU's devfreq to reduce frequency, when in fact the opposite is what is
> >   *   needed.
> >   *
> > - * To this end, deadline hint(s) can be set on a &dma_fence via &dma_fence_set_deadline.
> > + * To this end, deadline hint(s) can be set on a &dma_fence via &dma_fence_set_deadline
> > + * (or indirectly via userspace facing ioctls like &SYNC_IOC_SET_DEADLINE).
> >   * The deadline hint provides a way for the waiting driver, or userspace, to
> >   * convey an appropriate sense of urgency to the signaling driver.
>
> Hi,
>
> when the kernel HTML doc is generated, I assume the above becomes a
> link to "DOC: SYNC_IOC_SET_DEADLINE - set a deadline on a fence", right?

Heh, kernel docs completely miss the sync_file uABI.. I'll add a patch
to correct that in order to make these links work properly.

BR,
-R

> >   *
> > diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
> > index af57799c86ce..418021cfb87c 100644
> > --- a/drivers/dma-buf/sync_file.c
> > +++ b/drivers/dma-buf/sync_file.c
> > @@ -350,6 +350,22 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
> >       return ret;
> >  }
> >
> > +static int sync_file_ioctl_set_deadline(struct sync_file *sync_file,
> > +                                     unsigned long arg)
> > +{
> > +     struct sync_set_deadline ts;
> > +
> > +     if (copy_from_user(&ts, (void __user *)arg, sizeof(ts)))
> > +             return -EFAULT;
> > +
> > +     if (ts.pad)
> > +             return -EINVAL;
> > +
> > +     dma_fence_set_deadline(sync_file->fence, ns_to_ktime(ts.deadline_ns));
> > +
> > +     return 0;
> > +}
> > +
> >  static long sync_file_ioctl(struct file *file, unsigned int cmd,
> >                           unsigned long arg)
> >  {
> > @@ -362,6 +378,9 @@ static long sync_file_ioctl(struct file *file, unsigned int cmd,
> >       case SYNC_IOC_FILE_INFO:
> >               return sync_file_ioctl_fence_info(sync_file, arg);
> >
> > +     case SYNC_IOC_SET_DEADLINE:
> > +             return sync_file_ioctl_set_deadline(sync_file, arg);
> > +
> >       default:
> >               return -ENOTTY;
> >       }
> > diff --git a/include/uapi/linux/sync_file.h b/include/uapi/linux/sync_file.h
> > index ee2dcfb3d660..49325cf6749b 100644
> > --- a/include/uapi/linux/sync_file.h
> > +++ b/include/uapi/linux/sync_file.h
> > @@ -67,6 +67,21 @@ struct sync_file_info {
> >       __u64   sync_fence_info;
> >  };
> >
> > +/**
> > + * struct sync_set_deadline - set a deadline hint on a fence
> > + * @deadline_ns: absolute time of the deadline
>
> Is it legal to pass zero as deadline_ns?
>
> > + * @pad:     must be zero
> > + *
> > + * The timebase for the deadline is CLOCK_MONOTONIC (same as vblank)
>
> Does something here provide doc links to "DOC: SYNC_IOC_SET_DEADLINE -
> set a deadline on a fence" and to the "DOC: deadline hints"?
>
> > + */
> > +struct sync_set_deadline {
> > +     __u64   deadline_ns;
> > +     /* Not strictly needed for alignment but gives some possibility
> > +      * for future extension:
> > +      */
> > +     __u64   pad;
> > +};
> > +
> >  #define SYNC_IOC_MAGIC               '>'
> >
> >  /**
> > @@ -95,4 +110,11 @@ struct sync_file_info {
> >   */
> >  #define SYNC_IOC_FILE_INFO   _IOWR(SYNC_IOC_MAGIC, 4, struct sync_file_info)
> >
> > +/**
> > + * DOC: SYNC_IOC_SET_DEADLINE - set a deadline on a fence
> > + *
> > + * Allows userspace to set a deadline on a fence, see dma_fence_set_deadline()
>
> Does something here provide doc links to struct sync_set_deadline and
> to the "DOC: deadline hints"?
>
> > + */
> > +#define SYNC_IOC_SET_DEADLINE        _IOW(SYNC_IOC_MAGIC, 5, struct sync_set_deadline)
> > +
> >  #endif /* _UAPI_LINUX_SYNC_H */
>
> With all those links added:
> Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
>
>
> Thanks,
> pq