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sc16is7xx: Allow sharing the IRQ line

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When the interrupt line is shared with other devices, the IRQ must be
level-triggered, as only one device can trigger a falling edge. To support
this, try to acquire the IRQ with IRQF_TRIGGER_LOW|IRQF_SHARED first.

Interrupt controllers that lack support for level-triggers will return an
error, in which case the driver will now retry the acqusition with
IRQF_TRIGGER_FALLING, which was also the default before.

Signed-off-by: Daniel Mack <daniel@zonque.org>
Link: https://lore.kernel.org/r/20200521091152.404404-6-daniel@zonque.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Daniel Mack
2020-05-21 11:11:51 +02:00
committed by Greg Kroah-Hartman
parent 6393ff1c44
commit 2d12fc792c
1 changed files with 13 additions and 1 deletions
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14
drivers/tty/serial/sc16is7xx.c
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@ -1293,7 +1293,19 @@ static int sc16is7xx_probe(struct device *dev,
sc16is7xx_power(&s->p[i].port, 0);
}
/* Setup interrupt */
/*
* Setup interrupt. We first try to acquire the IRQ line as level IRQ.
* If that succeeds, we can allow sharing the interrupt as well.
* In case the interrupt controller doesn't support that, we fall
* back to a non-shared falling-edge trigger.
*/
ret = devm_request_threaded_irq(dev, irq, NULL, sc16is7xx_irq,
IRQF_TRIGGER_LOW | IRQF_SHARED |
IRQF_ONESHOT,
dev_name(dev), s);
if (!ret)
return 0;
ret = devm_request_threaded_irq(dev, irq, NULL, sc16is7xx_irq,
IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
dev_name(dev), s);