Messages in this thread | | | Subject | Re: [PATCH v3 8/9] dma-buf/sync_file: Add SET_DEADLINE ioctl | From | Christian König <> | Date | Mon, 27 Sep 2021 10:53:28 +0200 |
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Am 27.09.21 um 10:42 schrieb Pekka Paalanen: > On Fri, 3 Sep 2021 11:47:59 -0700 > 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. >> >> Signed-off-by: Rob Clark <robdclark@chromium.org> >> --- >> drivers/dma-buf/sync_file.c | 19 +++++++++++++++++++ >> include/uapi/linux/sync_file.h | 20 ++++++++++++++++++++ >> 2 files changed, 39 insertions(+) >> >> diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c >> index 394e6e1e9686..f295772d5169 100644 >> --- a/drivers/dma-buf/sync_file.c >> +++ b/drivers/dma-buf/sync_file.c >> @@ -459,6 +459,22 @@ 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, ktime_set(ts.tv_sec, ts.tv_nsec)); >> + >> + return 0; >> +} >> + >> static long sync_file_ioctl(struct file *file, unsigned int cmd, >> unsigned long arg) >> { >> @@ -471,6 +487,9 @@ 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..f67d4ffe7566 100644 >> --- a/include/uapi/linux/sync_file.h >> +++ b/include/uapi/linux/sync_file.h >> @@ -67,6 +67,18 @@ struct sync_file_info { >> __u64 sync_fence_info; >> }; >> >> +/** >> + * struct sync_set_deadline - set a deadline on a fence >> + * @tv_sec: seconds elapsed since epoch >> + * @tv_nsec: nanoseconds elapsed since the time given by the tv_sec >> + * @pad: must be zero > Hi Rob, > > I think you need to specify which clock this timestamp must be in. > > Which epoch? Sounds a bit like CLOCK_REALTIME to me which would not > make sense.
Most likely CLOCK_MONOTONIC I think since that's what ktime is based on as well IIRC.
My recollection might be wrong but I think Daniel documented somewhere that an absolut 64bit nanosecond value should be used for timeouts in IOCTLs which is sufficient for ~500 years uptime.
So the separation between seconds and nanoseconds might be redundant.
Regards, Christian.
> > Also I cannot guess how a compositor should be using this, so > explaining the expected usage would be really good, with reasons for > why should userspace bother. > > > Thanks, > pq > >> + */ >> +struct sync_set_deadline { >> + __s64 tv_sec; >> + __s32 tv_nsec; >> + __u32 pad; >> +}; >> + >> #define SYNC_IOC_MAGIC '>' >> >> /** >> @@ -95,4 +107,12 @@ 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() >> + */ >> +#define SYNC_IOC_SET_DEADLINE _IOW(SYNC_IOC_MAGIC, 5, struct sync_set_deadline) >> + >> #endif /* _UAPI_LINUX_SYNC_H */
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