Re: [PATCH v2 2/2] gpiolib: check the 'ngpios' property in core gpiolib code

On Thu, Nov 18, 2021 at 05:38:14PM +0100, Bartosz Golaszewski wrote:

On Thu, Nov 18, 2021 at 4:46 PM Andy Shevchenko
[off-list ref] wrote:

quoted

On Thu, Nov 18, 2021 at 02:23:17PM +0100, Bartosz Golaszewski wrote:

quoted

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.

Thanks for update, my comment below.

...

quoted

      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) {
+                     chip_err(gc, "tried to insert a GPIO chip with zero lines\n");

quoted

+                     ret = -EINVAL;

Sorry, forgot to ask, why this is needed?

What do you mean? 0 lines doesn't sound like a valid value so -EINVAL
is in order.

What is so special about -EINVAL? Why ret can't be returned?


-- 
With Best Regards,
Andy Shevchenko