Re: [PATCH 7/8] gpio: bd73800: Support ROHM BD73800 PMIC GPIOs

[Matti Vaittinen]

ma 13.7.2026 klo 11.16 Bartosz Golaszewski (brgl@xxxxxxxxxx) kirjoitti:
>
> On Sun, 12 Jul 2026 17:42:17 +0200, Matti Vaittinen
> <mazziesaccount@xxxxxxxxx> said:
> > pe 3.7.2026 klo 16.11 Bartosz Golaszewski (brgl@xxxxxxxxxx) kirjoitti:
> >> > +
> >> > +     if (!g->num_pins) {
> >> > +             /*
> >> > +              * The BD73800 may or may not have pins allocated for GPIO
> >> > +              * depending on the OTP used at manufacturing. Free the memory
> >> > +              * and go out if there is no pins as then we have nothing to do
> >> > +              */
> >> > +             dev_dbg(dev, "no GPIO pins\n");
> >> > +             devm_kfree(dev, g);
> >>
> >> No need for that, because...
> >>
> >> > +             return 0;
> >>
> >> ... this will still leave a bound device in the system, I'm not sure we want
> >> it? The correct error code in this case is -ENODEV.
> >
> > I am a bit uncertain. This isn't really an error. It should be very
> > much Ok to configure the support for PMICs with GPIOs to be compiled -
> > and also very much Ok to have a PMIC with no GPIOs. Returning an error
> > doesn't feel right. Furthermore, I am afraid that returning an error
> > might hurt the system start-up? Do you see some really problematic
> > consequences if we return Ok without registering the GPIOs. I'd assume
> > that wastes some bytes but I don't see other really severe
> > consequences.
>
> But -ENODEV/-ENXIO error codes are meant to do exactly that - tell the driver
> core to assume this device legitimately cannot be enabled on this system. There
> will be no error splat in the kernel log and the probe will not be deferred.

Oh, thanks for the explanation. I didn't know this. The -ENODEV not
causing error splat makes sense. The fact that -ENXIO does that too is
quite surptizing to me. I thought the -ENXIO is used to indicate
unexpected failure in bus communication.

I'll go with -ENODEV in the next version.

Yours,
    -- Matti

-- 

Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland

~~ When things go utterly wrong vim users can always type :help! ~~

Discuss - Estimate - Plan - Report and finally accomplish this:
void do_work(int time) __attribute__ ((const));