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Linux kernel stable tree
08e5c36410
The subdev state locking macros and macros to get the active state are currently behind CONFIG_MEDIA_CONTROLLER. This makes sense, as there can be no subdev state without MC. However, we have code paths common to MC and non-MC cases which call subdev operations that have subdev state as a parameter. In the non-MC case the state parameter would always be NULL. Thus it makes sense to allow, e.g.: v4l2_subdev_call_state_active(sd, pad, get_fmt, fmt) which for non-MC case would call the subdev passing NULL as the state. This currently fails: https://lore.kernel.org/oe-kbuild-all/202312061101.PLrz5NnJ-lkp@intel.com/ Fix the issue by moving the related macros to be outside CONFIG_MEDIA_CONTROLLER. The v4l2_subdev_lock_state() and v4l2_subdev_unlock_state() macros will crash if given NULL as the state, but the other macros behave correctly even when there's no active state, and they will only call the lock/unlock macros if there is a state. An alternative fix would be to make another version of v4l2_subdev_call_state_try() with ifdefs, which would not use any state macros and would always pass NULL as the state. But having two version of a macro/function is always more confusing than having just one, so I went this way. So, this fixes the v4l2_subdev_call_state_active() macro. But we also have v4l2_subdev_call_state_try(). It would be possible to fix that macro by additionally creating "no-op" variants of the state alloc and free functions. However, v4l2_subdev_call_state_try() is only used by a single driver (stm32-dcmi), which selects MC, and the macro is supposed to be removed as soon as the users have been converted away from the macro. Thus I have not touched the state alloc/free functions, and I think it makes sense to keep alloc/free functions available only if there's actually something that can be allocated or freed. Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> Link: https://lore.kernel.org/r/20231208-v4l2-state-mc-fix-v1-1-a0c8162557c6@ideasonboard.com Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> |
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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.