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pinctrl: bcm2835: Clear the event latch register when disabling interrupts

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It's possible to hit a race condition if interrupts are generated on a GPIO
pin when the IRQ line in question is being disabled.

If the interrupt is freed, bcm2835_gpio_irq_disable() is called which
disables the event generation sources (edge, level). If an event occurred
between the last disabling of hard IRQs and the write to the event
source registers, a bit would be set in the GPIO event detect register
(GPEDSn) which goes unacknowledged by bcm2835_gpio_irq_handler()
so Linux complains loudly.

There is no per-GPIO mask register, so when disabling GPIO interrupts
write 1 to the relevant bit in GPEDSn to clear out any stale events.

Signed-off-by: Jonathan Bell <jonathan@raspberrypi.org>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Jonathan Bell 2015-06-30 12:35:39 +01:00 committed by Linus Walleij
parent c10372e615
commit 714b1dd8f7
1 changed files with 2 additions and 0 deletions
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2
drivers/pinctrl/bcm/pinctrl-bcm2835.c
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@ -473,6 +473,8 @@ static void bcm2835_gpio_irq_disable(struct irq_data *data)
spin_lock_irqsave(&pc->irq_lock[bank], flags);
bcm2835_gpio_irq_config(pc, gpio, false);
/* Clear events that were latched prior to clearing event sources */
bcm2835_gpio_set_bit(pc, GPEDS0, gpio);
clear_bit(offset, &pc->enabled_irq_map[bank]);
spin_unlock_irqrestore(&pc->irq_lock[bank], flags);
}