Re: [PATCH 1/2] pinctrl/amd: only handle irq if it is pending and unmasked

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Tue, Jul 17, 2018 at 2:57 AM Daniel Kurtz <djkurtz@xxxxxxxxxxxx> wrote:

> The AMD pinctrl driver demultiplexes GPIO interrupts and fires off their
> individual handlers.
>
> If one of these GPIO irqs is configured as a level interrupt, and its
> downstream handler is a threaded ONESHOT interrupt, the GPIO interrupt
> source is masked by handle_level_irq() until the eventual return of the
> threaded irq handler.  During this time the level GPIO interrupt status
> will still report as high until the actual gpio source is cleared - both
> in the individual GPIO interrupt status bit (INTERRUPT_STS_OFF) and in
> its corresponding "WAKE_INT_STATUS_REG" bit.
>
> Thus, if another GPIO interrupt occurs during this time,
> amd_gpio_irq_handler() will see that the (masked-and-not-yet-cleared)
> level irq is still pending and incorrectly call its handler again.
>
> To fix this, have amd_gpio_irq_handler() check for both interrupts status
> and mask before calling generic_handle_irq().
>
> Note: Is it possible that this bug was the source of the interrupt storm
> on Ryzen when using chained interrupts before commit ba714a9c1dea85
> ("pinctrl/amd: Use regular interrupt instead of chained")?
>
> Signed-off-by: Daniel Kurtz <djkurtz@xxxxxxxxxxxx>

Patch applied with TGLX ACK.

Yours,
Linus Walleij
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