diff mbox series

[v3,1/2] gpiolib: improve coding style for local variables

Message ID 20211124122850.7095-1-brgl@bgdev.pl
State Superseded
Headers show
Series [v3,1/2] gpiolib: improve coding style for local variables | expand

Commit Message

Bartosz Golaszewski Nov. 24, 2021, 12:28 p.m. UTC 
Drop unneeded whitespaces and put the variables of the same type
together for consistency with the rest of the code.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
v1 -> v2:
- keep initializations on separate lines

 drivers/gpio/gpiolib.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Comments

Bartosz Golaszewski Nov. 24, 2021, 2:42 p.m. UTC | #1 
On Wed, Nov 24, 2021 at 3:35 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Wed, Nov 24, 2021 at 01:28:49PM +0100, Bartosz Golaszewski wrote:
> > Drop unneeded whitespaces and put the variables of the same type
> > together for consistency with the rest of the code.
>
> I thought I gave my tag, nevermind, here we are
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
>

I removed it because the patch changed. Thanks!

Bart
Andy Shevchenko Nov. 24, 2021, 2:46 p.m. UTC | #2 
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);
		/*
		 * -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)
			ngpios = 0;
		else if (ret)
			return ret;

		gc->ngpio = ngpios;
	}

	if (gc->ngpio == 0) {
		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
>
Bartosz Golaszewski Dec. 2, 2021, 10:26 a.m. UTC | #3 
On Thu, Nov 25, 2021 at 12:18 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Thu, Nov 25, 2021 at 11:10:08AM +0100, Bartosz Golaszewski wrote:
> > 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:
>
> ...
>
> > > > +             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.
>
> I don't think so. It is plain and self-explaining each step. See at the end of
> the message how.
>
> > >                 if (ret == -ENODATA)
> > >                         ngpios = 0;
> > >                 else if (ret)
> > >                         return ret;
>
> > You still need to goto err_free_descs here.
>
> Right, this doesn't affect the main point / logic 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?
>
> No, it's not right. The check is needed to tell that properties supplied 0.
>
> > >                 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)
>
> > I suggest the following:
>
> It's buggy as submitted version (I actually haven't found any difference in
> the code, but comments).
>
> You see, I propose less changes and straight forward logic:
>
> 1. Check if the supplied ->ngpio equal to 0
> 2. If so, try device properties
> 2.1. If there is no property found, make sure we a) don't use uninitialized
>      variable, b) we don't change ->ngpio, so it stays 0
> 2.2. If there is an error, return it as is to the caller
> 2.3. Assign ->ngpio by value from property (which very well may be 0!)

Ok, this is the thing I didn't realize, the property can indeed be 0
so your approach is correct.

Bart

> 3. Check ->ngpio for 0 again, if so, issue a message and return -EINVAL to
> the user.
>
> We have three places where ->ngpio can be 0, all of them I covered.
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
diff mbox series

Patch

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index abfbf546d159..ede8b8a7aa18 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -594,11 +594,11 @@  int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 			       struct lock_class_key *request_key)
 {
 	struct fwnode_handle *fwnode = gc->parent ? dev_fwnode(gc->parent) : NULL;
-	unsigned long	flags;
-	int		ret = 0;
-	unsigned	i;
-	int		base = gc->base;
 	struct gpio_device *gdev;
+	unsigned long flags;
+	int base = gc->base;
+	unsigned int i;
+	int ret = 0;
 
 	/*
 	 * First: allocate and populate the internal stat container, and