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

[Simon Horman <horms@xxxxxxxxxxxx>]

On Fri, Sep 09, 2016 at 06:57:54PM +0200, Geert Uytterhoeven wrote:
> 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?

Yes, I think that could be a winning combination.
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