power: supply: generic-adc-battery: Use GPIO descriptors

Hello Linus Walleij,

The patch b0327ffb133f: "power: supply: generic-adc-battery: Use GPIO descriptors" from Oct 30, 2020, leads to the following static checker warning:

drivers/power/supply/generic-adc-battery.c:97 gab_charge_finished()
warn: signedness bug returning '(-4095)'

drivers/power/supply/generic-adc-battery.c

    93  static bool gab_charge_finished(struct gab *adc_bat)
    94  {
    95          if (!adc_bat->charge_finished)
    96                  return false;
    97          return gpiod_get_value(adc_bat->charge_finished);

The gpiod_get_value() can return negative error codes so it's not necessarily clear if that should translate to a true as it does now or to a false...

    98  }

regards,
dan carpenter

It *can* do that but in 9999 cases out of 10000 it does not. Mostly because it just boils down to readin a register and masking a bit which does not fail. This only happens in the rare circumstance that the GPIO is on some slow bus that lost contact with the bridged device (such as an I2C or SPI chip).

I agree it is not a perfect (in the mathematical sense) API but in most cases the odd case of this call returning negative is ignored and there are thousands of in-kernel users.

If this is a real problem I would rather turn the call into a bool and ignore errors on the few that care to test for them than trying to augment all sites using this call to handle negative return codes.

Yours,
Linus Walleij