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pinctrl/amd: only handle irq if it is pending and unmasked

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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 ba714a9c1d
("pinctrl/amd: Use regular interrupt instead of chained")?

Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Daniel Kurtz 2018-07-16 18:57:18 -06:00 committed by Linus Walleij
parent 1766e4b704
commit 8bbed1eef0
1 changed files with 2 additions and 1 deletions
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3
drivers/pinctrl/pinctrl-amd.c
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@ -552,7 +552,8 @@ static irqreturn_t amd_gpio_irq_handler(int irq, void *dev_id)
/* Each status bit covers four pins */
for (i = 0; i < 4; i++) {
regval = readl(regs + i);
if (!(regval & PIN_IRQ_PENDING))
if (!(regval & PIN_IRQ_PENDING) ||
!(regval & BIT(INTERRUPT_MASK_OFF)))
continue;
irq = irq_find_mapping(gc->irq.domain, irqnr + i);
generic_handle_irq(irq);