Re: [PATCH v7 3/3] pinctrl: nuvoton: Add ma35d1 pinctrl and GPIO driver

[Jacky Huang]

Dear Andy,


On 2024/4/22 下午 04:16, Andy Shevchenko wrote:
> On Mon, Apr 22, 2024 at 7:10 AM Jacky Huang <ychuang570808@xxxxxxxxx> wrote:
> > On 2024/4/10 下午 04:54, Andy Shevchenko wrote:
> ...
>
> > > > +#define MA35_GP_MODE_MASK_WIDTH              2
> > > > +
> > > > +#define MA35_GP_SLEWCTL_MASK_WIDTH   2
> > > I looked at the code how you use these... Oh, please switch to FIELD_GET() /
> > > FIELD_PREP() (don't forget to include bitfield.h)
> > >
> > > ...
> > >
> > > ...
> > > > +             regval &= ~GENMASK(setting->shift + MA35_MFP_BITS_PER_PORT - 1,
> > > > +                                setting->shift);
> > > This will generate an awful code. Use respective FIELD_*() macros.
> > >
> > > ...
> > >
> > > > +     regval &= ~GENMASK(gpio * MA35_GP_MODE_MASK_WIDTH - 1,
> > > > +                        gpio * MA35_GP_MODE_MASK_WIDTH);
> > > > +     regval |= mode << gpio * MA35_GP_MODE_MASK_WIDTH;
> > > Ditto.
> > >
> > > ...
> > >
> > > > +     regval &= GENMASK(gpio * MA35_GP_MODE_MASK_WIDTH - 1,
> > > > +                       gpio * MA35_GP_MODE_MASK_WIDTH);
> > > > +
> > > > +     return regval >> gpio * MA35_GP_MODE_MASK_WIDTH;
> > > Ditto.
> ...
>
> > Allow me to remove irrelevant parts.
> >
> > I attempted to follow your advice and use FIELD_GET() and FIELD_PREP(),
> > but found
> > it impractical. The reason is that these two macros require their 'mask'
> > argument
> > to be a constant, otherwise compilation errors occur, which is the issue
> > I encountered.
> > Since the mask here is calculated and not a constant, compilation errors
> > occur.
> >
> > Taking MA35_GP_REG_MODE as an example, within 32 bits, every 2 bits
> > represent
> > the mode of a GPIO pin, and the mask is obtained by GENMASK(gpio * 2 -1,
> > gpio * 2),
> This is not good for the compiler, it can't figure out (at least in
> some _supported_ by Linux kernel versions on some architectures) that
> GENMASK can be constant here just left-shifted by arbitrary bits.
>
> > where the 'gpio' argument is a variable, not a constant, leading to
> > compilation
> > errors.
> >
> > Due to this reason, I will leave this part unchanged, or do you have any
> > other suggestions?
> If you need non-constant field_get()/field_prep(), add a new patch
> that moves them from drivers/iio/temperature/mlx90614.c (and there are
> more custom implementations:
> https://elixir.bootlin.com/linux/latest/A/ident/field_get) to the
> bitfield.h and use them in your code.

Thank you. It works for me. I will adopt the approach used in mlx90614.c.


Best Regards,
Jacky Huang