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From:   Bartosz Golaszewski <brgl@bgdev.pl>
Date:   Thu, 14 Dec 2023 15:56:37 +0100
Message-ID: <CAMRc=Mf4FpzLqQZ5phRZLbTsGCfdYaELZHnLM13vnWnkAkLXkQ@mail.gmail.com>
Subject: Re: [PATCH v2 2/5] gpiolib: cdev: relocate debounce_period_us from
 struct gpio_desc
To:     Kent Gibson <warthog618@gmail.com>
Cc:     linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org,
        linus.walleij@linaro.org, andy@kernel.org
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On Thu, Dec 14, 2023 at 3:45=E2=80=AFPM Kent Gibson <warthog618@gmail.com> =
wrote:
>
> On Thu, Dec 14, 2023 at 03:29:28PM +0100, Bartosz Golaszewski wrote:
> > On Thu, Dec 14, 2023 at 10:58=E2=80=AFAM Kent Gibson <warthog618@gmail.=
com> wrote:
> > >
> > >
> > > +/*
> > > + * Used to populate gpio_v2_line_info with cdev specific fields not =
contained
> > > + * in the struct gpio_desc.
> > > + * A line is determined to contain supplemental information by
> > > + * line_is_supplemental().
> > > + */
> > > +static struct {
> > > +       /* a rbtree of the struct lines containing the supplemental i=
nfo */
> > > +       struct rb_root tree;
> > > +       /* covers tree */
> > > +       spinlock_t lock;
> >
> > Looks like this is never taken from atomic context? Can this be a mutex=
 instead?
> >
>
> Correct, only from thread context.
>
> Can be a mutex, but it only covers tree lookups which should be quick
> as the tree is kept minimal, and I wouldn't expect it to ever get to the
> mutex slowpath, so a spinlock seemed more appropriate.
>

Fair enough.

Bart

> Cheers,
> Kent.