linux-kernel - Re: Disabling an interrupt in the handler locks the system up

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Date:   Fri, 21 Oct 2016 21:49:35 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Mason <slash.tmp@...e.fr>
cc:     Marc Zyngier <marc.zyngier@....com>,
        Jason Cooper <jason@...edaemon.net>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Sebastian Frias <sf84@...oste.net>
Subject: Re: Disabling an interrupt in the handler locks the system up

On Fri, 21 Oct 2016, Mason wrote:
> On 21/10/2016 21:14, Marc Zyngier wrote:
> > If connecting a device that signals its interrupt as level low to an
> > input line configured as level high doesn't strike you as a major
> > issue, nothing will. At that point, you can put anything you want in
> > your DT.
> 
> If I understand correctly, you are saying that I should have
> specified IRQ_TYPE_LEVEL_LOW, instead of IRQ_TYPE_LEVEL_HIGH?
> 
> If the HW outputs 1 when idle, and 0 when busy, that
> is level low? (Sorry if this is obvious, I'm absolutely
> clueless in this subject matter.)

We describe the level which is raising the interrupt. So in your case the
line goes to 0 when the interrupt is active, so the level is LOW.

Thanks,

	tglx