| Message ID | 20181212123901.34109-6-hverkuil-cisco@xs4all.nl (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | vb2/cedrus: use timestamps to identify buffers | expand |
On 2018-12-12 13:38, hverkuil-cisco@xs4all.nl wrote: > From: Hans Verkuil <hverkuil-cisco@xs4all.nl> > > We want to be able to uniquely identify buffers for stateless > codecs. The internal timestamp (a u64) as stored internally in the > kernel is a suitable candidate for that, but in struct v4l2_buffer > it is represented as a struct timeval. > > Add a v4l2_timeval_to_ns() function that converts the struct timeval > into a u64 in the same way that the kernel does. This makes it possible > to use this u64 elsewhere as a unique identifier of the buffer. > > Since timestamps are also copied from the output buffer to the > corresponding capture buffer(s) by M2M devices, the u64 can be > used to refer to both output and capture buffers. > > The plan is that in the future we redesign struct v4l2_buffer and use > u64 for the timestamp instead of a struct timeval (which has lots of > problems with 32 vs 64 bit and y2038 layout changes), and then there > is no more need to use this function. > > Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> > --- > include/uapi/linux/videodev2.h | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h > index 2db1635de956..3580c1ea4fba 100644 > --- a/include/uapi/linux/videodev2.h > +++ b/include/uapi/linux/videodev2.h > @@ -971,6 +971,18 @@ struct v4l2_buffer { > }; > }; > > +/** > + * v4l2_timeval_to_ns - Convert timeval to nanoseconds > + * @ts: pointer to the timeval variable to be converted > + * > + * Returns the scalar nanosecond representation of the timeval > + * parameter. > + */ > +static inline u64 v4l2_timeval_to_ns(const struct timeval *tv) > +{ > + return (__u64)tv->tv_sec * 1000000000ULL + tv->tv_usec * 1000; > +} This is causing a compile issue in userspace application, replacing u64 with __u64 solves the compile issue below. In file included from libavcodec/v4l2_request.h:22, from libavcodec/v4l2_request.c:28: /home/docker/LibreELEC/build.LibreELEC-H3.arm-9.0-devel/toolchain/armv7ve-libreelec-linux-gnueabi/sysroot/usr/include/linux/videodev2.h:975:19: error: unknown type name 'u64' static __inline__ u64 v4l2_timeval_to_ns(const struct timeval *tv) ^~~ Regards, Jonas > + > /* Flags for 'flags' field */ > /* Buffer is mapped (flag) */ > #define V4L2_BUF_FLAG_MAPPED 0x00000001
On 12/16/18 10:47 PM, Jonas Karlman wrote: > > On 2018-12-12 13:38, hverkuil-cisco@xs4all.nl wrote: >> From: Hans Verkuil <hverkuil-cisco@xs4all.nl> >> >> We want to be able to uniquely identify buffers for stateless >> codecs. The internal timestamp (a u64) as stored internally in the >> kernel is a suitable candidate for that, but in struct v4l2_buffer >> it is represented as a struct timeval. >> >> Add a v4l2_timeval_to_ns() function that converts the struct timeval >> into a u64 in the same way that the kernel does. This makes it possible >> to use this u64 elsewhere as a unique identifier of the buffer. >> >> Since timestamps are also copied from the output buffer to the >> corresponding capture buffer(s) by M2M devices, the u64 can be >> used to refer to both output and capture buffers. >> >> The plan is that in the future we redesign struct v4l2_buffer and use >> u64 for the timestamp instead of a struct timeval (which has lots of >> problems with 32 vs 64 bit and y2038 layout changes), and then there >> is no more need to use this function. >> >> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> >> --- >> include/uapi/linux/videodev2.h | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) >> >> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h >> index 2db1635de956..3580c1ea4fba 100644 >> --- a/include/uapi/linux/videodev2.h >> +++ b/include/uapi/linux/videodev2.h >> @@ -971,6 +971,18 @@ struct v4l2_buffer { >> }; >> }; >> >> +/** >> + * v4l2_timeval_to_ns - Convert timeval to nanoseconds >> + * @ts: pointer to the timeval variable to be converted >> + * >> + * Returns the scalar nanosecond representation of the timeval >> + * parameter. >> + */ >> +static inline u64 v4l2_timeval_to_ns(const struct timeval *tv) >> +{ >> + return (__u64)tv->tv_sec * 1000000000ULL + tv->tv_usec * 1000; >> +} > This is causing a compile issue in userspace application, replacing u64 > with __u64 solves the compile issue below. > > In file included from libavcodec/v4l2_request.h:22, > from libavcodec/v4l2_request.c:28: > /home/docker/LibreELEC/build.LibreELEC-H3.arm-9.0-devel/toolchain/armv7ve-libreelec-linux-gnueabi/sysroot/usr/include/linux/videodev2.h:975:19: > error: unknown type name 'u64' > static __inline__ u64 v4l2_timeval_to_ns(const struct timeval *tv) > ^~~ Oops, I missed that one. Fixed in my git branch. Thanks for reporting this! Hans > > Regards, > Jonas >> + >> /* Flags for 'flags' field */ >> /* Buffer is mapped (flag) */ >> #define V4L2_BUF_FLAG_MAPPED 0x00000001
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h index 2db1635de956..3580c1ea4fba 100644 --- a/include/uapi/linux/videodev2.h +++ b/include/uapi/linux/videodev2.h @@ -971,6 +971,18 @@ struct v4l2_buffer { }; }; +/** + * v4l2_timeval_to_ns - Convert timeval to nanoseconds + * @ts: pointer to the timeval variable to be converted + * + * Returns the scalar nanosecond representation of the timeval + * parameter. + */ +static inline u64 v4l2_timeval_to_ns(const struct timeval *tv) +{ + return (__u64)tv->tv_sec * 1000000000ULL + tv->tv_usec * 1000; +} + /* Flags for 'flags' field */ /* Buffer is mapped (flag) */ #define V4L2_BUF_FLAG_MAPPED 0x00000001