linux-kernel - Re: [PATCH v1 1/1] gpiolib: Return label, if set, for IRQ only line

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Date: Fri, 10 May 2024 18:42:28 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/1] gpiolib: Return label, if set, for IRQ only line

On Thu, May 09, 2024 at 04:23:07PM +0200, Bartosz Golaszewski wrote:
> On Thu, May 9, 2024 at 3:58 PM Andy Shevchenko
> <andy.shevchenko@...il.com> wrote:
> > Thu, May 09, 2024 at 03:15:05PM +0200, Bartosz Golaszewski kirjoitti:
> > > On Wed, May 8, 2024 at 4:47 PM Andy Shevchenko
> > > <andriy.shevchenko@...ux.intel.com> wrote:
> > > >
> > > > If line has been locked as IRQ without requesting,
> > > > still check its label and return it, if not NULL.
> > > >
> > > > Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> > > > ---
> > > >  drivers/gpio/gpiolib.c | 12 ++++++------
> > > >  1 file changed, 6 insertions(+), 6 deletions(-)
> > > >
> > > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> > > > index db536ec9734d..1f1673552767 100644
> > > > --- a/drivers/gpio/gpiolib.c
> > > > +++ b/drivers/gpio/gpiolib.c
> > > > @@ -105,16 +105,16 @@ const char *gpiod_get_label(struct gpio_desc *desc)
> > > >         unsigned long flags;
> > > >
> > > >         flags = READ_ONCE(desc->flags);
> > > > -       if (test_bit(FLAG_USED_AS_IRQ, &flags) &&
> > > > -           !test_bit(FLAG_REQUESTED, &flags))
> > > > -               return "interrupt";
> > > > -
> > > > -       if (!test_bit(FLAG_REQUESTED, &flags))
> > > > -               return NULL;
> > > >
> > > >         label = srcu_dereference_check(desc->label, &desc->srcu,
> > > >                                        srcu_read_lock_held(&desc->srcu));
> > > >
> > > > +       if (test_bit(FLAG_USED_AS_IRQ, &flags))
> > > > +               return label->str ?: "interrupt";
> > > > +
> > > > +       if (!test_bit(FLAG_REQUESTED, &flags))
> > > > +               return NULL;
> > > > +
> > > >         return label->str;
> > > >  }
> > >
> > > What good would it be if gpiochip_dup_line_label() returns NULL for
> > > unrequested lines anyway?
> >
> > Then it should be handled differently in those cases. So, consider it as
> > a preparatory patch which doesn't change current behaviour.
> >
> > (Yes, I have some hack patches locally which do something useful, but they are
> > not ready. In any case this one looks to me as a good cleanup on its own for
> > the sake of readability of the code and reduced amount of checks.)
> >
> 
> Fair enough but I would like to know what your bigger plan is before
> picking this up.

I stand corrected, this patch has an immediate effect on the generic
gpiolib_dbg_show() which does *not* use the above mentioned call..

-- 
With Best Regards,
Andy Shevchenko