linux-kernel - Re: [PATCH 12/20] gpio/rockchip: add return check for clock rate set

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Date:   Fri, 30 Sep 2022 11:28:23 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Jianqun Xu <jay.xu@...k-chips.com>
Cc:     linus.walleij@...aro.org, heiko@...ech.de,
        andriy.shevchenko@...ux.intel.com, robert.moore@...el.com,
        robh@...nel.org, linux-rockchip@...ts.infradead.org,
        linux-kernel@...r.kernel.org, lenb@...nel.org, rafael@...nel.org
Subject: Re: [PATCH 12/20] gpio/rockchip: add return check for clock rate set

On Fri, Sep 30, 2022 at 11:17 AM Bartosz Golaszewski <brgl@...ev.pl> wrote:
>
> On Tue, Sep 20, 2022 at 12:31 PM Jianqun Xu <jay.xu@...k-chips.com> wrote:
> >
> > Check if the clock rate set for the apb clock is successful or not.
> >
> > Signed-off-by: Jianqun Xu <jay.xu@...k-chips.com>
> > ---
> >  drivers/gpio/gpio-rockchip.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/gpio/gpio-rockchip.c b/drivers/gpio/gpio-rockchip.c
> > index e36cdbd4bbef..511e93a6a429 100644
> > --- a/drivers/gpio/gpio-rockchip.c
> > +++ b/drivers/gpio/gpio-rockchip.c
> > @@ -199,6 +199,9 @@ static int rockchip_gpio_set_debounce(struct gpio_chip *gc,
> >         if (bank->gpio_type == GPIO_TYPE_V2 && !IS_ERR(bank->db_clk)) {
> >                 div_debounce_support = true;
> >                 freq = clk_get_rate(bank->db_clk);
> > +               if (!freq)
> > +                       return -EINVAL;
> > +
> >                 max_debounce = (GENMASK(23, 0) + 1) * 2 * 1000000 / freq;
> >                 if (debounce > max_debounce)
> >                         return -EINVAL;
> > --
> > 2.25.1
> >
>
> This cannot happen, clk_get_rate() can only return 0 for clk == NULL.
> We're not using an optional clock.
>

Ah, sorry actually the db_clk can be NULL for certain variants. But in
that case shouldn't we just silently ignore it and return 0? Or return
-ENOTSUPP at the very least?

Bart