Re: [PATCH v4 06/11] gpio: add support for the sl28cpld GPIO controller

[Michael Walle]

Am 2020-06-05 14:00, schrieb Andy Shevchenko:
> On Fri, Jun 5, 2020 at 12:14 AM Michael Walle <michael@xxxxxxxx> wrote:
>
> > Add support for the GPIO controller of the sl28 board management
> > controller. This driver is part of a multi-function device.
> >
> > A controller has 8 lines. There are three different flavors:
> > full-featured GPIO with interrupt support, input-only and output-only.
>
> ...
>
> > +#include <linux/of_device.h>
>
> I think also not needed.
> But wait...
>
> > +       return devm_regmap_add_irq_chip_np(dev, dev_of_node(dev), 
> > regmap,
>
> It seems regmap needs to be converted to use fwnode.

Mhh, this _np functions was actually part of this series in the
beginning.

> > +                                          irq, IRQF_SHARED | 
> > IRQF_ONESHOT, 0,
> > +                                          irq_chip, &gpio->irq_data);
>
> ...
>
> > +       if (!pdev->dev.parent)
> > +               return -ENODEV;
>
> Are we expecting to get shot into foot? I mean why we need this check?

Can we be sure, that we always have a parent node? You are the first
which complains about this ;) There were some other comments to move
this to the beginning of the function.

> > +       dev_id = platform_get_device_id(pdev);
> > +       if (dev_id)
> > +               type = dev_id->driver_data;
>
> Oh, no. In new code we don't need this. We have facilities to provide
> platform data in a form of fwnode.

Ok I'll look into that.

But I already have a question, so there are of_property_read_xx(), which
seems to be the old functions, then there is device_property_read_xx() 
and
fwnode_property_read_xx(). What is the difference between the latter 
two?

> > +       else
> > +               type = 
> > (uintptr_t)of_device_get_match_data(&pdev->dev);
>
> So does this. device_get_match_data().
ok

> > +       if (!type)
> > +               return -ENODEV;
>
> ...
>
> > +       if (irq_support &&
>
> Why do you need this flag? Can't simple IRQ number be sufficient?

I want to make sure, the is no misconfiguration. Eg. only GPIO
flavors which has irq_support set, have the additional interrupt
registers.

> > +           device_property_read_bool(&pdev->dev, 
> > "interrupt-controller")) {
> > +               irq = platform_get_irq(pdev, 0);
> > +               if (irq < 0)
> > +                       return irq;
> > +
> > +               ret = sl28cpld_gpio_irq_init(&pdev->dev, gpio, regmap,
> > +                                            base, irq);
> > +               if (ret)
> > +                       return ret;
> > +
> > +               config.irq_domain = 
> > regmap_irq_get_domain(gpio->irq_data);
> > +       }
>
> ...
>
> > +static const struct of_device_id sl28cpld_gpio_of_match[] = {
>
> > +       { .compatible = "kontron,sl28cpld-gpio",
> > +         .data = (void *)SL28CPLD_GPIO },
> > +       { .compatible = "kontron,sl28cpld-gpi",
> > +         .data = (void *)SL28CPLD_GPI },
> > +       { .compatible = "kontron,sl28cpld-gpo",
> > +         .data = (void *)SL28CPLD_GPO },
>
> All above can be twice less LOCs.

They are longer than 80 chars. Or do I miss something?

> > +       {},
>
> No comma.

ok

> > +};
>
>
> ...
>
> > +               .name = KBUILD_MODNAME,
>
> This actually not good idea in long term. File name can change and 
> break an ABI.

Ahh an explanation, why this is bad. Ok makes sense, although to be 
fair,
.id_table should be used for the driver name matching. I'm not sure if
this is used somewhere else, though.


--
-michael