LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Bartosz Golaszewski <brgl@bgdev.pl>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Linus Walleij <linus.walleij@linaro.org>,
	Johan Hovold <johan@kernel.org>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 2/2] gpiolib: check the 'ngpios' property in core gpiolib code
Date: Thu, 25 Nov 2021 11:10:08 +0100	[thread overview]
Message-ID: <CAMRc=Mfcph_YPryowhtGtb9G_GOveRm+27BJYyznjxc=BK-jWg@mail.gmail.com> (raw)
In-Reply-To: <YZ5QYsu2ed5FiSWE@smile.fi.intel.com>

On Wed, Nov 24, 2021 at 3:47 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Wed, Nov 24, 2021 at 01:28:50PM +0100, Bartosz Golaszewski wrote:
> > Several drivers read the 'ngpios' device property on their own, but
> > since it's defined as a standard GPIO property in the device tree bindings
> > anyway, it's a good candidate for generalization. If the driver didn't
> > set its gc->ngpio, try to read the 'ngpios' property from the GPIO
> > device's firmware node before bailing out.
>
> > Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
> > Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
> > ---
> > v1 -> v2:
> > - use device_property_read_u32() instead of fwnode_property_read_u32()
> > - reverse the error check logic
> >
> > v2 -> v3:
> > - don't shadow errors other than -ENODATA in device_property_read_u32()
> >
> >  drivers/gpio/gpiolib.c | 15 ++++++++++++---
> >  1 file changed, 12 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> > index ede8b8a7aa18..f79fd2551cf7 100644
> > --- a/drivers/gpio/gpiolib.c
> > +++ b/drivers/gpio/gpiolib.c
> > @@ -599,6 +599,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
> >       int base = gc->base;
> >       unsigned int i;
> >       int ret = 0;
> > +     u32 ngpios;
> >
> >       /*
> >        * First: allocate and populate the internal stat container, and
> > @@ -647,9 +648,17 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
> >       }
>
> >       if (gc->ngpio == 0) {
> > -             chip_err(gc, "tried to insert a GPIO chip with zero lines\n");
> > -             ret = -EINVAL;
> > -             goto err_free_descs;
> > +             ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios);
> > +             if (ret) {
> > +                     if (ret == -ENODATA) {
> > +                             chip_err(gc, "tried to insert a GPIO chip with zero lines\n");
> > +                             ret = -EINVAL;
> > +                     }
> > +
> > +                     goto err_free_descs;
> > +             }
>
> And if the property returns 0 in ngpios?
>
> What about the modified suggestion from previous version:
>
>         if (gc->ngpio == 0) {
>                 ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios);

The comment is a good idea but other than that - it's overcomplicating things.

>                 if (ret == -ENODATA)
>                         ngpios = 0;
>                 else if (ret)
>                         return ret;

You still need to goto err_free_descs here.

>
>                 gc->ngpio = ngpios;
>         }
>
>         if (gc->ngpio == 0) {

Why check that again? We already know the driver set it to 0, we
checked it a couple lines before. If we can't get the setting from the
properties then it won't be non 0 here right?

>                 chip_err(gc, "tried to insert a GPIO chip with zero lines\n");
>                 ret = -EINVAL;
>                 goto err_free_descs;
>         }
>
> ?
>
> > +             gc->ngpio = ngpios;
> >       }
> >
> >       if (gc->ngpio > FASTPATH_NGPIO)
> > --
> > 2.25.1
> >
>
> --
> With Best Regards,
> Andy Shevchenko
>
>

I suggest the following:

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index ede8b8a7aa18..08c1e8fc0dfa 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -599,6 +599,7 @@ int gpiochip_add_data_with_key(struct gpio_chip
*gc, void *data,
     int base = gc->base;
     unsigned int i;
     int ret = 0;
+    u32 ngpios;

     /*
      * First: allocate and populate the internal stat container, and
@@ -647,9 +648,23 @@ int gpiochip_add_data_with_key(struct gpio_chip
*gc, void *data,
     }

     if (gc->ngpio == 0) {
-        chip_err(gc, "tried to insert a GPIO chip with zero lines\n");
-        ret = -EINVAL;
-        goto err_free_descs;
+        /*
+         * If the driver didn't specify the number of GPIOs, try to
+         * get this value from the device properties as a fall-back.
+         */
+        ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios);
+        if (ret) {
+            /*
+             * -ENODATA means that there is no property found and
+             * we want to issue the error message to the user.
+             * Besides that, we want to return different error code
+             * to state that supplied value is not valid.
+             * */
+            if (ret == -ENODATA) {
+                chip_err(gc, "tried to insert a GPIO chip with zero lines\n");
+                ret = -EINVAL;
+            }
+
+            goto err_free_descs;
+        }
+
+        gc->ngpio = ngpios;
     }

     if (gc->ngpio > FASTPATH_NGPIO)

  parent reply	other threads:[~2021-11-25 10:14 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-24 12:28 [PATCH v3 1/2] gpiolib: improve coding style for local variables Bartosz Golaszewski
2021-11-24 12:28 ` [PATCH v3 2/2] gpiolib: check the 'ngpios' property in core gpiolib code Bartosz Golaszewski
2021-11-24 14:46   ` Andy Shevchenko
2021-11-24 14:49     ` Andy Shevchenko
2021-11-25 10:10     ` Bartosz Golaszewski [this message]
2021-11-25 11:18       ` Andy Shevchenko
2021-12-02 10:26         ` Bartosz Golaszewski
2021-11-24 14:35 ` [PATCH v3 1/2] gpiolib: improve coding style for local variables Andy Shevchenko
2021-11-24 14:42   ` Bartosz Golaszewski

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAMRc=Mfcph_YPryowhtGtb9G_GOveRm+27BJYyznjxc=BK-jWg@mail.gmail.com' \
    --to=brgl@bgdev.pl \
    --cc=andriy.shevchenko@linux.intel.com \
    --cc=johan@kernel.org \
    --cc=linus.walleij@linaro.org \
    --cc=linux-gpio@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --subject='Re: [PATCH v3 2/2] gpiolib: check the '\''ngpios'\'' property in core gpiolib code' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).