Commit 2d12fc79 authored May 21, 2020 by Daniel Mack Committed by Greg Kroah-Hartman May 22, 2020

sc16is7xx: Allow sharing the IRQ line

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>

parent 6393ff1c

drivers/tty/serial/sc16is7xx.c

+13 −1

Original line number	Diff line number	Diff line
		@@ -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);

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