Re: [PATCH 3/3] pinctrl: qcom: Clear possible pending irq when remuxing GPIOs

[Marc Zyngier]

On 2020-11-24 10:37, Maulik Shah wrote:

[...]

> >   static int msm_pinmux_set_mux(struct pinctrl_dev *pctldev,
> >   			      unsigned function,
> >   			      unsigned group)
> >   {
> >   	struct msm_pinctrl *pctrl = pinctrl_dev_get_drvdata(pctldev);
> > +	struct gpio_chip *gc = &pctrl->chip;
> > +	unsigned int irq = irq_find_mapping(gc->irq.domain, group);
> >   	const struct msm_pingroup *g;
> >   	unsigned long flags;
> >   	u32 val, mask;
> > +	u32 oldval;
> > +	u32 old_i;
> >   	int i;
> >     	g = &pctrl->soc->groups[group];
> > @@ -187,15 +215,26 @@ static int msm_pinmux_set_mux(struct pinctrl_dev 
> > *pctldev,
> >   	if (WARN_ON(i == g->nfuncs))
> >   		return -EINVAL;
> >   -	raw_spin_lock_irqsave(&pctrl->lock, flags);
> > +	disable_irq(irq);
> >   -	val = msm_readl_ctl(pctrl, g);
> > +	raw_spin_lock_irqsave(&pctrl->lock, flags);
> > +	oldval = val = msm_readl_ctl(pctrl, g);
> >   	val &= ~mask;
> >   	val |= i << g->mux_bit;
> >   	msm_writel_ctl(val, pctrl, g);
> > -
> >   	raw_spin_unlock_irqrestore(&pctrl->lock, flags);
> >   +	/*
> > +	 * Clear IRQs if switching to/from GPIO mode since muxing to/from
> > +	 * the GPIO path can cause phantom edges.
> > +	 */
> > +	old_i = (oldval & mask) >> g->mux_bit;
> > +	if (old_i != i &&
> > +	    (i == pctrl->soc->gpio_func || old_i == pctrl->soc->gpio_func))
> > +		msm_pinctrl_clear_pending_irq(pctrl, group, irq);
>
> disable_irq() and enable_irq() should be moved inside this if loop. as
> only use for this is to mask the IRQ when switching back to gpio IRQ
> mode?
>
> i also don't think we should leave IRQ enabled at the end of this
> function by default, probably need to check if IRQ was already
> unmasked before disabling it, then only call enable_irq().

Why? It looks to me that this reproduces the behaviour of 
IRQCHIP_SET_TYPE_MASKED, which is highly desirable. What
problem are you trying to address with this?

> > +
> > +	enable_irq(irq);
> > +
> >   	return 0;
> >   }
> >   @@ -456,32 +495,45 @@ static const struct pinconf_ops 
> > msm_pinconf_ops = {
> >   static int msm_gpio_direction_input(struct gpio_chip *chip, unsigned 
> > offset)
> >   {
> >   	const struct msm_pingroup *g;
> > +	unsigned int irq = irq_find_mapping(chip->irq.domain, offset);
> >   	struct msm_pinctrl *pctrl = gpiochip_get_data(chip);
> >   	unsigned long flags;
> > +	u32 oldval;
> >   	u32 val;
> >     	g = &pctrl->soc->groups[offset];
> >   +	disable_irq(irq);
> > +
> >   	raw_spin_lock_irqsave(&pctrl->lock, flags);
> >   -	val = msm_readl_ctl(pctrl, g);
> > +	oldval = val = msm_readl_ctl(pctrl, g);
> >   	val &= ~BIT(g->oe_bit);
> >   	msm_writel_ctl(val, pctrl, g);
> >     	raw_spin_unlock_irqrestore(&pctrl->lock, flags);
> >   +	if (oldval != val)
> > +		msm_pinctrl_clear_pending_irq(pctrl, offset, irq);
> > +
> > +	enable_irq(irq);
>
> i do not think we need disable_irq() and enable_irq() here, changing
> direction to input does not mean its being used for interrupt only, it
> may be set to use something like Rx mode in UART.
>
> the client driver should enable IRQ when needed.

And the kernel doesn't expect random interrupts to fire. Again, what
are you trying to fix by removing these?

        M.
--
Jazz is not dead. It just smells funny...