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From: Bartosz Golaszewski <brgl@bgdev.pl>
Date: Thu, 1 Feb 2024 09:43:17 +0100
Message-ID: <CAMRc=Mcu2DbuvdeXugEr4w+sW0qLF7g9zDi8paoN1DpRtoVHSg@mail.gmail.com>
Subject: Re: [PATCH 00/22] gpio: rework locking and object life-time control
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Kent Gibson <warthog618@gmail.com>, Alex Elder <elder@linaro.org>, 
	Geert Uytterhoeven <geert+renesas@glider.be>, "Paul E . McKenney" <paulmck@kernel.org>, 
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>, Wolfram Sang <wsa@the-dreams.de>, 
	linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, 
	Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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On Wed, Jan 31, 2024 at 9:32=E2=80=AFPM Linus Walleij <linus.walleij@linaro=
org> wrote:
>
> On Tue, Jan 30, 2024 at 1:48=E2=80=AFPM Bartosz Golaszewski <brgl@bgdev.p=
l> wrote:
>
> > We do NOT serialize all API callbacks. This means that provider callbac=
ks
> > may be called simultaneously and GPIO drivers need to provide their own
> > locking if needed. This is on purpose. First: we only support exclusive
> > GPIO usage[1] so there's no risk of two drivers getting in each other's
> > way over the same GPIO. Second: with this series, we ensure enough
> > consistency to limit the chance of drivers or user-space users crashing
> > the kernel. With additional improvements in handling the flags field in
> > GPIO descriptors there's very little to gain, while bitbanging drivers
> > may care about the increased performance of going lockless.
>
> OK I read this before but didn't understand it, now I understand it.
>
> The series:
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
>
> I think you should merge it all soon so we get some time to shake
> it out in linux-next, hopefully any remaining bugs and cleanups
> can be done in-tree.
>
> Excellent work, by the way.
>

Thanks. There are still a few issues here and there, so I'll be
sending a v2 next week.

Bart

> Yours,
> Linus Walleij