Re: [PATCH/RFC] gpio: rcar: Add clock support

[Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>]

Hi Kaneko-san, Matsuoka-san,

On Sun, Feb 15, 2015 at 4:46 PM, Yoshihiro Kaneko <ykaneko0929@xxxxxxxxx> wrote:
> From: Koji Matsuoka <koji.matsuoka.xm@xxxxxxxxxxx>
>
> The clock of GPIO is an initial value of enable. However,
> since correction which sets the clock to disable was added
> by the boot loader, the clock control was added.

Thanks for your patch!

Are you sure you this is really needed to enable the GPIO module clocks?

While I'm still using the original U-Boot that doesn't disable (almost) all
MSTP clocks, I do use my own early startup code that disables (almost) all
MSTP clocks to make sure I don't miss enabling any clocks, and the GPIO
clocks are enabled by the call to pm_runtime_get_sync() in gpio_rcar_probe(),
added in commit df0c6c80232f ("gpio: rcar: Add minimal runtime PM support").

> diff --git a/drivers/gpio/gpio-rcar.c b/drivers/gpio/gpio-rcar.c
> index c49522e..6d4a0bc 100644
> --- a/drivers/gpio/gpio-rcar.c
> +++ b/drivers/gpio/gpio-rcar.c

> @@ -367,6 +369,13 @@ static int gpio_rcar_probe(struct platform_device *pdev)
>
>         platform_set_drvdata(pdev, p);
>
> +       p->clk = devm_clk_get(&pdev->dev, NULL);
> +       if (IS_ERR(p->clk)) {
> +               dev_err(&pdev->dev, "failed to get access to GPIO clock\n");
> +               return PTR_ERR(p->clk);
> +       }
> +       clk_prepare_enable(p->clk);
> +
>         pm_runtime_enable(dev);
>         pm_runtime_get_sync(dev);

With some extra debugging code on Koelsch:

    gpio_rcar_probe:370
--> MSTP gpio0 ON
    gpio_rcar_probe:373
    gpiochip_find_base: found new base at 992
    GPIO chip e6050000.gpio: created GPIO range 0->31 ==> e6060000.pfc PIN 0->31
    gpiochip_add: registered GPIOs 992 to 1023 on device: e6050000.gpio
    gpio_rcar e6050000.gpio: driving 32 GPIOs

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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