irq-sifive-plic + gpio-sifive break IRQF_ONESHOT

irq-sifive-plic + gpio-sifive break IRQF_ONESHOT

[Charles Papon]

Hi,

Was using a chip driver (W5500) which use a threaded irq with the
IRQF_TRIGGER_LOW | IRQF_ONESHOT flags and i got some issues.

The interrupt should have been masked to wait the W5500 irq handler to
be executed, but that wasn't the case.

As far my understanding go, the plic driver should use
handle_level_irq instead of handle_simple_irq, as interrupts connected
on it could be level triggerd.

Also, the plic irq_mask/irq_unmask should be implemented for two reasons :
- If they are null, it make crash chained_irq_enter calls from let's
say connected gpio drivers durring IRQ handeling
- the irq_unmask is very much required to handle threaded IRQF_ONESHOT IRQ

So maybe the plic claim release (writel(hwirq, claim);) should be
moved into its irq_unmask, and the irq_mask should be implemented as a
dummy function.


The same kind of issue appeared witht eh gpio-sifive driver, the
driver is using  handle_level_irq instead of handle_simple_irq and do
not implement the unmask, which break the IRQF_ONESHOT handeling.

Do you agree ? I'm not experienced in linux dev.
Thanks

Charles

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