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SubjectRe: [PATCH v3 2/2] gpiolib: check the 'ngpios' property in core gpiolib code
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
>

--
With Best Regards,
Andy Shevchenko


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