linux-kernel - Re: Threaded irq handler question

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Message-ID: <r2l87a5b0801004220351h4ba2d1ect49c33893a30806e9@mail.gmail.com>
Date:	Thu, 22 Apr 2010 11:51:06 +0100
From:	Will Newton <will.newton@...il.com>
To:	Yong Zhang <yong.zhang@...driver.com>
Cc:	Linux Kernel list <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: Threaded irq handler question

On Thu, Apr 22, 2010 at 2:37 AM, Yong Zhang <yong.zhang@...driver.com> wrote:
> On Wed, Apr 21, 2010 at 05:35:32PM +0100, Will Newton wrote:
>> Hi all,
>> My problem is that this structure does not work, because once I call
>> disable_irq_nosync() on the irq in the check handler the thread will
>> no longer run because the irq is disabled. However if I don't call
>> disable_irq_nosync() I will get endless irqs because the line is
>> level-triggered and will not be deasserted until the thread has run.
>>
>> Could someone tell me what I'm doing wrong here?
>
> Does IRQF_ONESHOT meet your need?

Almost I think, but I believe if my check handler does not wake the
thread then I don't get another interrupt ever. I can fix this by
making my check handler always return WAKE_THREAD, which is slightly
sub-optimal, but not a big problem.

Thank you for your help!
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