linux-kernel - Re: mfd regmap irq to handle some cases

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Message-ID: <20120123115225.GB29465@opensource.wolfsonmicro.com>
Date:	Mon, 23 Jan 2012 11:52:25 +0000
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Ashish Jangam <ashish.jangam@...tcummins.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: mfd regmap irq to handle some cases

On Mon, Jan 23, 2012 at 02:17:03PM +0530, Ashish Jangam wrote:

Please fix your mailer to word wrap within 80 columns.  I've reflowed
your text for legibility.

> For a quick fix in regmap irq we may tempt to defer event
> clarification after processing of event but there is a problem in this

That's not going to work in general, it means there's a race between
handling the interrupt and acknowledging the interrupt which leads to
interrupts being dropped if you get a new interrupt before the ack has
been written back.

> approach for some variants of DA9052 and DA9053 when event is cleared
> a spurious interrupt gets generated therefore in earlier release of
> DA9052/53 MFD module a delay was added. Therefore we need to think on
> how to handle such cases in regmap irq.

What are the consequences of the spurious interrupt?
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