linux-kernel - Re: [PATCH] gpio: Document the 'valid

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Message-ID: <CACRpkdZtWLGAn0K+xENY+RF6CsWPn0m7R--W9EaH+xTKazALFg@mail.gmail.com>
Date: Wed, 26 Feb 2025 11:18:54 +0100
From: Linus Walleij <linus.walleij@...aro.org>
To: Matti Vaittinen <mazziesaccount@...il.com>
Cc: Matti Vaittinen <matti.vaittinen@...rohmeurope.com>, Bartosz Golaszewski <brgl@...ev.pl>, 
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gpio: Document the 'valid_mask' being internal

On Wed, Feb 26, 2025 at 7:09 AM Matti Vaittinen
<mazziesaccount@...il.com> wrote:
> On 25/02/2025 23:36, Linus Walleij wrote:
> > we can maybe move it to struct gpio_device in
> > drivers/gpio/gpiolib.h?
> >
> > This struct exist for every gpio_chip but is entirely gpiolib-internal.
> >
> > Then it becomes impossible to do it wrong...
>
> True. I can try seeing what it'd require to do that. But ... If there
> are any drivers out there altering the valid_mask _after_ registering
> the driver to the gpio-core ... Then it may be a can of worms and I may
> just keep the lid closed :)

That's easy to check with some git grep valid_mask
and intuition. I think all calls actually changing the valid_mask
are in the init_valid_mask() callback as they should be.

> Furthermore, I was not 100% sure the valid_mask was not intended to be
> used directly by the drivers. I hoped you and Bart have an opinion on that.

Oh it was. First we just had .valid_mask and then it was
manipulated directly.

Then we introduced init_valid_mask() and all users switched over
to using that.

So evolution, not intelligent design...

Yours,
Linus Walleij