Re: [PATCH 3/3] pinctrl: sh-pfc: r8a7794: Implement voltage switching for SDHI

[Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>]

Hi Simon,

On Fri, Sep 9, 2016 at 5:26 PM, Simon Horman <horms@xxxxxxxxxxxx> wrote:
>> > +       /* GP6_16-23 -> bits 31-24 of pocctrl
>> > +        * GP6_06    -> bit  23    of pocctrl
>> > +        * GP6_00-05 -> bits 22-17 of pocctrl
>> > +        * GP6_07    -> bit  16    of pocctrl
>> > +        * GP6_14    -> bit  15    of pocctrl
>> > +        * GP6_08-13 -> bits 14-09 of pocctrl
>> > +        * GP6_15    -> bit  08    of pocctrl
>> > +        */
>> > +       if (pin == RCAR_GP_PIN(6, 6) || pin == RCAR_GP_PIN(6, 14))
>> > +               return 31 - 2 - (pin & 0x1f);
>> > +       else if (pin == RCAR_GP_PIN(6, 7) || pin == RCAR_GP_PIN(6, 15))
>> > +               return 31 - 8 - (pin & 0x1f);
>> > +       else if (pin < RCAR_GP_PIN(6, 14))
>> > +               return 31 - 9 - (pin & 0x1f);
>> > +       else
>> > +               return 31 + 16 - (pin & 0x1f);
>>
>> While your code is correct, I think it's easier for the casual reader to use
>> a plain switch () statement, and let the optimizer handle the rest.
>
> Like this? If so I don't particularly mind but it doesn't seem clearer to
> me.
>
> +static int r8a7794_pin_to_pocctrl(struct sh_pfc *pfc, unsigned int pin, u32 *pocctrl)
> +{
> +       *pocctrl = 0xe606006c;
> +
> +       switch (pin) {
> +       case RCAR_GP_PIN(6, 0):
> +               return 22;
> +       case RCAR_GP_PIN(6, 1):
> +               return 21;

Right, a full list of cases indeed doesn't look that much better.

Note that you can use "switch (pin & 0x1f)", and have ranges in case
statements:

        switch (pin & 0x1f) {
        case 6: return 23:
        case 7: return 16;
        case 14: return 15;
        case 15: return 8;
        case 0...5:
        case 7...13:
                return 22 - (pin & 0x1f);
        case 16..23:
                return 47 - (pin & 0x1f);
        }

Does that look better?

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

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
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