On 12/16/18 10:47 PM, Jonas Karlman wrote:
>
> On 2018-12-12 13:38, [email protected] wrote:
>> From: Hans Verkuil <[email protected]>
>>
>> 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 <[email protected]>
>> ---
>> 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
