Re: [PATCH v2 12/18] gpio: madera: Support Cirrus Logic Madera class codecs

[Richard Fitzgerald]

On Tue, 2017-04-25 at 16:13 +0200, Linus Walleij wrote:
> On Mon, Apr 24, 2017 at 6:08 PM, Richard Fitzgerald
> <rf@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> 
> > This adds support for the GPIOs on Cirrus Logic Madera class codecs.
> > Any pins not used for special functions (see the pinctrl driver) can be
> > used as general single-bit input or output lines. The number of available
> > GPIOs varies between codecs.
> >
> > Signed-off-by: Nariman Poushin <nariman@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Richard Fitzgerald <rf@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Charles Keepax <ckeepax@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
> > ---
> > Changes from V1:
> > - dt bindings moved to a separate patch
> > - dependent on pinctrl driver instead of parent MFD
> > - added get_direction function
> > - added .request / .free / .set_config to work with pinctrl driver
> > - register range with pinctrl driver
> 
> Nice, but...
> 
> > +       ret = gpiochip_add_pin_range(&madera_gpio->gpio_chip, "madera-pinctrl",
> > +                                    0, 0, madera_gpio->gpio_chip.ngpio);
> > +       if (ret) {
> > +               dev_warn(&pdev->dev, "Failed to add pin range (%d)\n", ret);
> > +               return ret;
> > +       }
> 
> This is all fine, but we have generic code for adding ranges from
> the device tree, see
> Documentation/devicetree/bindings/gpio/gpio.txt
> 

The range of gpio pins is a fixed property of the chip, and so is the
combination of gpio+pinctrl drivers.

I think the general principle of the DT maintainers is that DT should be
used for things that the drivers don't already know and can't figure
out.

> With that this range should not even be needed.
> Apart from that it looks pretty solid.
> 
> Yours,
> Linus Walleij