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commit8310ca9407upstream. DST_QUEUE_OFF_BASE is applied to offset/mem_offset on MMAP capture buffers only for the VIDIOC_QUERYBUF ioctl, while the userspace fields (including offset/mem_offset) are filled in for VIDIOC_{QUERY,PREPARE,Q,DQ}BUF ioctls. This leads to differences in the values presented to userspace. If userspace attempts to mmap the capture buffer directly using values from DQBUF, it will fail. Move the code that applies the magic offset into a helper, and call that helper from all four ioctl entry points. [hverkuil: drop unnecessary '= 0' in v4l2_m2m_querybuf() for ret] Fixes:7f98639def("V4L/DVB: add memory-to-memory device helper framework for videobuf") Fixes:908a0d7c58("[media] v4l: mem2mem: port to videobuf2") Signed-off-by: Chen-Yu Tsai <wenst@chromium.org> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org> [OP: backport to 5.4: adjusted return logic in v4l2_m2m_qbuf() to match the logic in the original commit: call v4l2_m2m_adjust_mem_offset() only if !ret and before the v4l2_m2m_try_schedule() call] Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.