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Date: Fri, 19 Mar 2010 16:41:56 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Marc Zyngier <maz@misterjones.org>
Cc: Eric Miao <eric.y.miao@gmail.com>, LKML <linux-kernel@vger.kernel.org>,
       Jebediah Huang <jebediah.huang@gmail.com>
Subject: Re: [PATCH] gpio: add interrupt handling capability to max732x
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On Tue, 16 Mar 2010 11:34:52 +0100
Marc Zyngier <maz@misterjones.org> wrote:

> +static irqreturn_t max732x_irq_handler(int irq, void *devid)
> +{
> +	struct max732x_chip *chip = devid;
> +	uint8_t pending;
> +	uint8_t level;
> +
> +	pending = max732x_irq_pending(chip);
> +
> +	if (!pending)
> +		return IRQ_HANDLED;

Should be IRQ_NONE?

If this device was on a shared interrupt line and the interrupt was
caused by some other device, and this handler is called first then the
incorrect IRQ_HANDLED return could cause the irq core to do wrong things.


> +	do {
> +		level = __ffs(pending);
> +		handle_nested_irq(level + chip->irq_base);
> +
> +		pending &= ~(1 << level);
> +	} while (pending);
> +
> +	return IRQ_HANDLED;
> +}