Re: [PATCH v3 2/2] pwm: loongson: Reload PWM configuration through counter reset

[Uwe Kleine-König]

Hello,

On Thu, Sep 10, 2026 at 07:58:12PM +0800, Keguang Zhang wrote:
> On Mon, Sep 7, 2026 at 5:33 PM Uwe Kleine-König <ukleinek@xxxxxxxxxx> wrote:
> > [...] I wonder if the fix is incomplete. If at driver bind time
> > LOONGSON_PWM_CTRL_REG_RST isn't set and there are still wrong values in
> > the shadowed LOW and PERIOD registers the first period will be wrong.
> >
> > This would need:
> >
> >         val = pwm_loongson_readl(ddata, LOONGSON_PWM_REG_CTRL);
> > +
> > +       /*
> > +        * Ensure that the values of LOW and PERIOD are sampled into
> > +        * the shadow register when the hardware starts running.
> > +        */
> > +       if (!(val & LOONGSON_PWM_CTRL_REG_RST))
> > +               pwm_loongson_writel(ddata, val | LOONGSON_PWM_CTRL_REG_RST, LOONGSON_PWM_REG_CTRL);
> > +
> >         val &= ~LOONGSON_PWM_CTRL_REG_RST;
> >         val |= LOONGSON_PWM_CTRL_REG_EN;
> >         pwm_loongson_writel(ddata, val, LOONGSON_PWM_REG_CTRL);
> >
> > I think.
> 
> You are right that this patch doesn't handle the initial hardware
> state when the driver binds.
> Would you prefer that I submit a follow-up patch to address this, or
> are you planning to fix it yourself?

I don't have the hardware, so if you do that and test it, that's very
appreciated.

Best regards
Uwe

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