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

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Message-ID: <20140728064913.GH6758@twins.programming.kicks-ass.net>
Date:	Mon, 28 Jul 2014 08:49:13 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
	Linux PM list <linux-pm@...r.kernel.org>
Subject: Re: [RFC][PATCH] irq: Rework IRQF_NO_SUSPENDED

On Sat, Jul 26, 2014 at 01:49:17PM +0200, Rafael J. Wysocki wrote:
> One more idea, on top of the prototype patch that I posted
> (https://patchwork.kernel.org/patch/4625921/).
> 
> The problem with enable_irq_wake() is that it only takes one argument, so
> if that's a shared interrupt, we can't really say which irqaction is supposed
> to handle wakeup interrupts should they occur.

Right.

> To address this we can introduce enable_device_irq_wake() that will take
> an additional dev_id argument (that must be the one passed to request_irq() or
> the operation will fail) that can be used to identify the irqaction for
> handling the wakeup interrupts.  It can work by setting IRQF_NO_SUSPEND
> for the irqaction in question and doing the rest along the lines of
> irq_set_irq_wake(irq, 1).  disable_device_irq_wake() will then clear
> IRQF_NO_SUSPEND (it also has to be passed the dev_id argument).
> 
> If we have that, the guys who need to set up device interrupts (ie. interrupts
> normally used for signaling input events etc) for system wakeup will need to
> use enable_device_irq_wake() and that should just work.

So in the patch I posted I described why NO_SUSPEND is useful, I still
have to hear a solid reason for why we also need enable_irq_wake()? What
does it do that cannot be achieved with NO_SUSPEND?

I realize its dynamic, but that's crap, at device registration time it
pretty much already knows if its a wakeup source or not, right?
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