Re: [PATCH v3 5/7] gpio: Add GPIO Aggregator/Repeater driver

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Harish,

On Tue, Dec 3, 2019 at 6:42 AM Harish Jenny K N
<harish_kandiga@mentor.com> wrote:
> > +static int gpio_aggregator_probe(struct platform_device *pdev)
> > +{
> > +     struct device *dev = &pdev->dev;
> > +     struct gpio_desc **descs;
> > +     struct gpiochip_fwd *fwd;
> > +     int i, n;
> > +
> > +     n = gpiod_count(dev, NULL);
> > +     if (n < 0)
> > +             return n;
> > +
> > +     descs = devm_kmalloc_array(dev, n, sizeof(*descs), GFP_KERNEL);
> > +     if (!descs)
> > +             return -ENOMEM;
> > +
> > +     for (i = 0; i < n; i++) {
> > +             descs[i] = devm_gpiod_get_index(dev, NULL, i, GPIOD_ASIS);
>
> can you please add this check as well as we need to return EPROBE_DEFER.
>
> if (desc[i] == ERR_PTR(-ENOENT))
> <                 return -EPROBE_DEFER;

So gpiod_get_index() nevers return -EPROBE_DEFER, but returns -ENOENT
instead?
How can a driver distinguish between "GPIO not found" and "gpiochip driver
not yet initialized"?
Worse, so the *_optional() variants will return NULL in both cases, too, so
the caller will always fall back to optional GPIO not present?

Or am I missing something?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds