On 12/19/19 6:49 AM, Jungo Lin wrote: > For Camera AR(Augmented Reality) application requires camera timestamps > to be reported with CLOCK_BOOTTIME to sync timestamp with other sensor > sources. > > The boottime timestamp is identical to monotonic timestamp, > except it also includes any time that the system is suspended. > > Signed-off-by: Jungo Lin <jungo.lin@xxxxxxxxxxxx> > --- > Changes from v6: > - No change. > --- > Documentation/media/uapi/v4l/buffer.rst | 11 ++++++++++- > include/uapi/linux/videodev2.h | 2 ++ > 2 files changed, 12 insertions(+), 1 deletion(-) > > diff --git a/Documentation/media/uapi/v4l/buffer.rst b/Documentation/media/uapi/v4l/buffer.rst > index 9149b57728e5..f45bfce7fddd 100644 > --- a/Documentation/media/uapi/v4l/buffer.rst > +++ b/Documentation/media/uapi/v4l/buffer.rst > @@ -662,13 +662,22 @@ Buffer Flags > - 0x00002000 > - The buffer timestamp has been taken from the ``CLOCK_MONOTONIC`` > clock. To access the same clock outside V4L2, use > - :c:func:`clock_gettime`. > + :c:func:`clock_gettime` using clock IDs ``CLOCK_MONOTONIC``. IDs -> ID > * .. _`V4L2-BUF-FLAG-TIMESTAMP-COPY`: > > - ``V4L2_BUF_FLAG_TIMESTAMP_COPY`` > - 0x00004000 > - The CAPTURE buffer timestamp has been taken from the corresponding > OUTPUT buffer. This flag applies only to mem2mem devices. > + * .. _`V4L2_BUF_FLAG_TIMESTAMP_BOOTIME`: You mistyped BOOTTIME as BOOTIME in a lot of places. Please check. > + > + - ``V4L2_BUF_FLAG_TIMESTAMP_BOOTIME`` > + - 0x00008000 > + - The buffer timestamp has been taken from the ``CLOCK_BOOTTIME`` > + clock. To access the same clock outside V4L2, use > + :c:func:`clock_gettime` using clock IDs ``CLOCK_BOOTTIME``. IDs -> ID > + Identical to CLOCK_MONOTONIC, except it also includes any time that > + the system is suspended. > * .. _`V4L2-BUF-FLAG-TSTAMP-SRC-MASK`: > > - ``V4L2_BUF_FLAG_TSTAMP_SRC_MASK`` > diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h > index 04481c717fee..74ef9472e702 100644 > --- a/include/uapi/linux/videodev2.h > +++ b/include/uapi/linux/videodev2.h > @@ -1060,6 +1060,8 @@ static inline __u64 v4l2_timeval_to_ns(const struct timeval *tv) > #define V4L2_BUF_FLAG_TIMESTAMP_UNKNOWN 0x00000000 > #define V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC 0x00002000 > #define V4L2_BUF_FLAG_TIMESTAMP_COPY 0x00004000 > +#define V4L2_BUF_FLAG_TIMESTAMP_BOOTIME 0x00008000 This should be 0x00006000. (flags & V4L2_BUF_FLAG_TIMESTAMP_MASK) is a value that determines the timestamp source, so these timestamp defines are values, not bitmasks. However, I don't like your approach. Whether to use MONOTONIC or BOOTTIME is really a userspace decision, and locking a driver to one of these two options seems wrong to me. Instead add new V4L2_BUF_FLAG_USE_BOOTTIME flag that userspace can set when queuing the buffer and that indicates that instead of the MONOTONIC timestamp, it should return the BOOTTIME timestamp. This requires a simple helper function that returns either ktime_get_ns or ktime_get_boottime_ns based on the vb2_v4l2_buffer flags field. It's definitely more work (although it can be limited to drivers that use vb2), but much more useful. Regards, Hans > + > /* Timestamp sources. */ > #define V4L2_BUF_FLAG_TSTAMP_SRC_MASK 0x00070000 > #define V4L2_BUF_FLAG_TSTAMP_SRC_EOF 0x00000000 >
