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cbd9463da1
v4l2_m2m_job_finish() is typically called when
DMA operations complete, in interrupt handlers or DMA
completion callbacks. Calling .device_run from v4l2_m2m_job_finish
creates a nasty re-entrancy path into the driver.
Moreover, some implementation of .device_run might need to sleep,
as is the case for drivers supporting the Request API,
where controls are applied via v4l2_ctrl_request_setup,
which takes the ctrl handler mutex.
This commit adds a deferred context that calls v4l2_m2m_try_run,
and gets scheduled by v4l2_m2m_job_finish().
Before this change, device_run would be called from these
paths:
vb2_m2m_request_queue, or
v4l2_m2m_streamon, or
v4l2_m2m_qbuf
v4l2_m2m_try_schedule
v4l2_m2m_try_run
.device_run
v4l2_m2m_job_finish
v4l2_m2m_try_run
.device_run
After this change, the latter is now gone and instead:
v4l2_m2m_device_run_work
v4l2_m2m_try_run
.device_run
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
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.