On Fri, 3 Sep 2021 16:56:43 +0300
Alexandru Ardelean [off-list ref] wrote:

On Fri, 3 Sept 2021 at 16:40, Andy Shevchenko
[off-list ref] wrote:

quoted

On Fri, Sep 03, 2021 at 10:29:13AM +0300, Alexandru Ardelean wrote:  

quoted

This change introduces a device-managed variant to the
iio_map_array_register() function. It's a simple implementation of calling
iio_map_array_register() and registering a callback to
iio_map_array_unregister() with the devm_add_action_or_reset().

The function uses an explicit 'dev' parameter to bind the unwinding to. It
could have been implemented to implicitly use the parent of the IIO device,
however it shouldn't be too expensive to callers to just specify to which
device object to bind this unwind call.
It would make the API a bit more flexible.  

AFAIU this dev pointer is kinda discussable thing. What scenario do you expect
(have in mind) when it shouldn't use parent?  

So, this brings me back to an older discussion about devm_ when I
thought about making some devm_ function that implicitly takes uses
the parent of the IIO device.

Jonathan mentioned that if we go that route, maybe we should prefix it
with iiom_ .
But we weren't sure at the time if that makes sense.
The idea was to bind the management of the unwinding to either the
parent of the IIO device, or the IIO device itself (indio_dev->dev).

I'm not keen on playing the same games that say pcim does where it
effectively combines all cleanup into one devres call because that
can end up doing things in an order that isn't strict reversal if
the setup path isn't carefully organised.  It's 'clever' but to my mind
doing something similar in IIO would need to subtle bugs.

So we would simply be using iiom_ as a shortcut to say bind to the parent
device.  Might be worth considering long term but I'm not keen to do
it for a random little used function first!

Series looks good to me, but I'll let it sit a little longer before applying.

Jonathan

We kind of concluded that it may probably not be a good to hide
anything and make standard a devm_ function with an explicit 'dev'
object parameter.

I found a recent mention here (while searching for iiom_  on linux-iio):
https://lore.kernel.org/linux-iio/20210313192150.74c0a91b@archlinux/ (local)

quoted

--
With Best Regards,
Andy Shevchenko