linux-kernel - Re: [RFC][PATCH] irq: Rework IRQF_NO

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Date:	Fri, 25 Jul 2014 23:00:12 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
cc:	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org,
	Linux PM list <linux-pm@...r.kernel.org>
Subject: Re: [RFC][PATCH] irq: Rework IRQF_NO_SUSPENDED

On Fri, 25 Jul 2014, Rafael J. Wysocki wrote:
> On Friday, July 25, 2014 03:25:41 PM Peter Zijlstra wrote:
> > OK, so Rafael said there's devices that keep on raising their interrupt
> > until they get attention. Ideally this won't happen because the device
> > is suspended etc.. But I'm sure there's some broken piece of hardware
> > out there that'll make it go boom.
> 
> So here's an idea.
> 
> What about returning IRQ_NONE rather than IRQ_HANDLED for "suspended"
> interrupts (after all, that's what a sane driver would do for a
> suspended device I suppose)?
> 
> If the line is really shared and the interrupt is taken care of by
> the other guy sharing the line, we'll be all fine.
> 
> If that is not the case, on the other hand, and something's really
> broken, we'll end up disabling the interrupt and marking it as
> IRQS_SPURIOUS_DISABLED (if I understand things correctly).

We should not wait 100k unhandled interrupts in that case. We know
already at the first unhandled interrupt that the shit hit the fan.

I'll have a deeper look how we can sanitize the whole wake/no_suspend
logic vs. shared interrupts. Need to look at the usage sites first.

Thanks,

	tglx







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