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

From: Alexandre Torgue
Date: Wed Feb 19 2020 - 08:18:02 EST

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);
 +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

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.

The most important to regenerate gic interrupt (associate to the exti
line) is to write in SWIER register.

Quite. Hence my question.