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Add 'min_reqbufs_allocation' field in the vb2_queue structure so drivers can specify the minimum number of buffers to allocate when calling VIDIOC_REQBUFS. When initializing the queue, v4l2 core makes sure that the following constraints are respected: - the minimum number of buffers to allocate must be at least 2 because one buffer is used by the hardware while the other is being processed by userspace. -if the driver needs 'min_queued_buffers' in the queue before calling start_streaming(), then the minimum requirement is 'min_queued_buffers + 1' to keep at least one buffer available for userspace. Simplify __vb2_init_fileio() by using 'min_reqbufs_allocation' directly to avoid duplicating the minimum number of buffers to allocate computation. Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com> Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
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 reStructuredText 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.