Re: [PATCH v5 2/9] drivers: irqchip: Add STM32 external interrupts support

[Alexandre Torgue]

Hi Thomas,

On 09/14/2016 11:19 AM, Thomas Gleixner wrote:
> On Tue, 13 Sep 2016, Alexandre Torgue wrote:
> > On 09/13/2016 05:21 PM, Thomas Gleixner wrote:
> > > On Fri, 9 Sep 2016, Alexandre TORGUE wrote:
> > > > +static void stm32_exti_free(struct irq_domain *d, unsigned int virq,
> > > > +			    unsigned int nr_irqs)
> > > > +{
> > > > +	struct irq_data *data = irq_get_irq_data(virq);
> > > > +
> > > > +	irq_gc_mask_clr_bit(data->parent_data);
> > >
> > > I have a hard time to understand this. The irq domain is not hierarchical.
> >
> > Actually, I wanted to test ".free" callback function of gpio_irq_domain in
> > STM32 pinctrl driver. To do that I modified gpio driver: just after getting
> > virq through gpio_to_irq, I called "irq_dispose_mapping(virq)".
> > I know it is dirty but I thought it was the only way to test.
> >
> > Doing that, I see that ".free" callback of gpio domain is called but as it is
> > hirerchical ".free" callback for parent domain (exti one) is also called. I
> > observed that virq was well unmapped, but not masked at exti level. It is for
> > this reason than I added "irq_gc_mask_clr_bit(data->parent_data);" which mask
> > interrupt at exti level.
>
> Aargh. I really misread the patch, but this is entirely non obvious and you
> should do:
>
>        struct irq_data *data = irq_domain_get_irq_data(d, virq);
>
>        irq_gc_mask_clr_bit(d);
>
> Then it is entirely clear that you mask the interrupt of _this_ (the exti)
> domain.

Ok, it's easier to understand like that.

> Now what really bugs me is that you do that at all. An interrupt which is
> freed must be masked already. Why is it unmasked in the first place?

Honestly I don't know. When "devm_free_irq" is called to release virq, 
there is no issue and interrupt is well masked. But, when I tried to use
"irq_dispose_mapping(virq)" I observed that .free is called (child and 
parent domain) but interrupt is not masked.

Regards

Alex

> Thanks,
>
> 	tglx