Re: [PATCH v1 1/2] pinctrl: pinctrl-loongson2: add pinctrl driver support

[Yinbo Zhu]

在 2022/10/21 下午5:45, Linus Walleij 写道:
> Hi Yinbo,
>
> thanks for your patch!
>
> On Fri, Oct 21, 2022 at 3:27 AM Yinbo Zhu <zhuyinbo@xxxxxxxxxxx> wrote:
>
> > The loongson2 SoC has a few pins that can be used as GPIOs or take
> > multiple other functions. Add a driver for the pinmuxing.
> >
> > There is currently no support for GPIO pin pull-up and pull-down.
> >
> > Signed-off-by: zhanghongchen <zhanghongchen@xxxxxxxxxxx>
> > Signed-off-by: Yinbo Zhu <zhuyinbo@xxxxxxxxxxx>
>
> (...)
>
> > +static int loongson2_pmx_set_mux(struct pinctrl_dev *pcdev, unsigned int func_num,
> > +                             unsigned int group_num)
> > +{
> > +       struct loongson2_pinctrl *pctrl = pinctrl_dev_get_drvdata(pcdev);
> > +       unsigned long reg = (unsigned long)pctrl->reg_base +
> > +                               loongson2_pmx_groups[group_num].reg;
> > +       unsigned int mux_bit = loongson2_pmx_groups[group_num].bit;
> > +       unsigned int val;
> > +       unsigned long flags;
> > +
> > +       raw_spin_lock_irqsave(&pctrl->lock, flags);
> > +       val = readl((void *)reg);
> > +       if (func_num == 0)
> > +               val &= ~(1<<mux_bit);
> > +       else
> > +               val |= (1<<mux_bit);
> > +       writel(val, (void *)reg);
> > +       raw_spin_unlock_irqrestore(&pctrl->lock, flags);
>
> Can you explain in the commit message or with a comment in the code
> why you have to use a raw spinlock for this?
>
> We usually only use raw spinlocks for things like low level
> interrupt handlers...
>
> My guess is that you can replace this with an ordinary spinlock.
I was refer other platform, eg. pinctrl-amd.c, if the ordinary spinlock 
was more appropriate I will use the ordinary spinlock.

TKs
Yinbo.
> Yours,
> Linus Walleij