Re: [PATCH RFC 3/7] pinctrl: sh-pfc: Rollback to mux if requires when the gpio is freed

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Hi Shimoda-san,

On Mon, Jul 8, 2019 at 11:08 AM Yoshihiro Shimoda
<yoshihiro.shimoda.uh@xxxxxxxxxxx> wrote:
> R-Car PWM controller requires the gpio to output zero duty,
> this patch allows to roll it back from gpio to mux when the gpio
> is freed.
>
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>

Thanks for your patch!

> --- a/drivers/pinctrl/sh-pfc/pinctrl.c
> +++ b/drivers/pinctrl/sh-pfc/pinctrl.c
> @@ -26,6 +26,7 @@
>  #include "../pinconf.h"
>
>  struct sh_pfc_pin_config {
> +       unsigned int mux_mark;

Due to padding, adding this field will increase memory consumption by
6 bytes per pin.
Probably sh_pfc_pin_group.{pins,mux} should be changed from unsigned int
to u16, but that's out of scope for this patch.

>         bool mux_set;
>         bool gpio_enabled;
>  };
> @@ -353,6 +354,15 @@ static int sh_pfc_func_set_mux(struct pinctrl_dev *pctldev, unsigned selector,
>         spin_lock_irqsave(&pfc->lock, flags);
>
>         for (i = 0; i < grp->nr_pins; ++i) {
> +               int idx = sh_pfc_get_pin_index(pfc, grp->pins[i]);
> +               struct sh_pfc_pin_config *cfg = &pmx->configs[idx];
> +
> +               /*
> +                * This doesn't assume the order which gpios are enabled
> +                * and then mux is set.

I'm sorry, I don't understand what you mean?
Can you please reword or elaborate?

> +                */
> +               WARN_ON(cfg->gpio_enabled);

Can this actually happen?
Should this cause a failure instead?

> +
>                 ret = sh_pfc_config_mux(pfc, grp->mux[i], PINMUX_TYPE_FUNCTION);
>                 if (ret < 0)
>                         goto done;
> @@ -364,6 +374,7 @@ static int sh_pfc_func_set_mux(struct pinctrl_dev *pctldev, unsigned selector,
>                 struct sh_pfc_pin_config *cfg = &pmx->configs[idx];
>
>                 cfg->mux_set = true;
> +               cfg->mux_mark = grp->mux[i];
>         }
>
>  done:
> @@ -417,6 +428,9 @@ static void sh_pfc_gpio_disable_free(struct pinctrl_dev *pctldev,
>
>         spin_lock_irqsave(&pfc->lock, flags);
>         cfg->gpio_enabled = false;
> +       /* If mux is already set, this configure it here */

configures

> +       if (cfg->mux_set)
> +               sh_pfc_config_mux(pfc, cfg->mux_mark, PINMUX_TYPE_FUNCTION);

Have you considered the case where more than one pin of a pinmux group
was used as a GPIO? In that case sh_pfc_gpio_disable_free() will be called
multiple times, possibly with the same mux_mark.

I don't think this will cause issues, though.

>         spin_unlock_irqrestore(&pfc->lock, flags);
>  }

Thanks!

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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