c2eb8effb2
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> Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.