Re: [PATCH v2] media: stm32: dcmi: Switch to __v4l2_subdev_state_alloc()

On 6/29/22 14:26, Tomi Valkeinen wrote:

[...]

quoted

quoted

Perhaps the best way to solve this is just to remove the underscores
from __v4l2_subdev_state_alloc, and change all the drivers which create
temporary v4l2_subdev_states to use that (and the free) functions. And
also create the helper macro which can be used in those cases where the
call is simple (the state is not modified or accessed by the caller).

As long as we prevent any new driver from using that API, that's fine
with me.

An alternative would be to keep the v4l2_subdev_state as a local 
variable (allocated in the stack), and add a new function, 
v4l2_subdev_state_local_init() or such. The function would initialize 
the given state, expecting the allocatable fields to be already 
allocated (state->pads, which in the above cases points to another local 
variable, i.e. stack).

This would prevent the need of a free call, which, while not complex as 
such, might cause a bigger amount of changes in some cases to handle the 
error paths correctly.

Of course, if the above-mentioned macro works, then that's the easiest 
solution. But that won't work for all drivers.

Don't you think a driver fix shouldn't involve "rework the subsystem" 
requirement to be applicable ?

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