Re: [PATCH v2 1/2] irqchip/stm32: Add irq retrigger support

[Alexandre Torgue]

On 2/19/20 2:13 PM, Marc Zyngier wrote:
> On 2020-02-19 13:07, Alexandre Torgue wrote:
> > On 2/19/20 12:43 PM, Marc Zyngier wrote:
> > > On 2020-02-19 11:33, Alexandre Torgue wrote:
> > > > Fix Marc email address
> > > >
> > > > On 2/18/20 2:12 PM, Alexandre Torgue wrote:
> > > > > This commit introduces retrigger support for stm32_ext_h chip.
> > > > > It consists to rise the GIC interrupt mapped to an EXTI line.
> > > > >
> > > > > Signed-off-by: Alexandre Torgue <alexandre.torgue@xxxxxx>
> > > > >
> > > > > diff --git a/drivers/irqchip/irq-stm32-exti.c 
> > > > > b/drivers/irqchip/irq-stm32-exti.c
> > > > > index e00f2fa27f00..c971d115edb4 100644
> > > > > --- a/drivers/irqchip/irq-stm32-exti.c
> > > > > +++ b/drivers/irqchip/irq-stm32-exti.c
> > > > > @@ -604,12 +604,24 @@ static void stm32_exti_h_syscore_deinit(void)
> > > > > ÂÂÂÂÂ unregister_syscore_ops(&stm32_exti_h_syscore_ops);
> > > > > Â }
> > > > > Â +static int stm32_exti_h_retrigger(struct irq_data *d)
> > > > > +{
> > > > > +ÂÂÂ struct stm32_exti_chip_data *chip_data = 
> > > > > irq_data_get_irq_chip_data(d);
> > > > > +ÂÂÂ const struct stm32_exti_bank *stm32_bank = chip_data->reg_bank;
> > > > > +ÂÂÂ void __iomem *base = chip_data->host_data->base;
> > > > > +ÂÂÂ u32 mask = BIT(d->hwirq % IRQS_PER_BANK);
> > > > > +
> > > > > +ÂÂÂ writel_relaxed(mask, base + stm32_bank->swier_ofst);
> > > > > +
> > > > > +ÂÂÂ return irq_chip_retrigger_hierarchy(d);
> > >
> > > Calling irq_chip_retrigger_hierarchy here is really odd. If the write
> > > above has the effect of making the interrupt pending again, why do you
> > > need to force the retrigger any further?
> >
> > To be honest, as we use hierarchical irq_chip, I thought it was the
> > way to follow (to retrigger parent irq_chip). It makes maybe no sens
> > here.
>
> Indeed, it looks perfectly pointless. What irq_chip_retrigger_hierarchy()
> does is to look for the first parent irqchip that is able to retrigger
> the interrupt. Guess what, you've just done that already. And once you've
> generated the interrupt, you don't need to ask the other irqchips in the
> chain to do the same thing.

I agree. I gonna remove it v3.

Thanks for the feeback.
Alex

> > The most important to regenerate gic interrupt (associate to the exti
> > line) is to write in SWIER register.
>
> Quite. Hence my question.
>
>  ÂÂÂÂÂÂÂ M.