From mboxrd@z Thu Jan  1 00:00:00 1970
From: rjw@rjwysocki.net (Rafael J. Wysocki)
Date: Wed, 11 Feb 2015 15:31:18 +0100
Subject: [PATCH v4 3/5] irqchip: Add DT binding doc for the virtual irq
 demuxer chip
In-Reply-To: <20150211111516.GB9154@leverpostej>
References: <1422527620-8308-1-git-send-email-boris.brezillon@free-electrons.com>
 <20150211091159.GE7119@twins.programming.kicks-ass.net>
 <20150211111516.GB9154@leverpostej>
Message-ID: <32372622.IiYZ15O7e1@vostro.rjw.lan>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Wednesday, February 11, 2015 11:15:17 AM Mark Rutland wrote:
> On Wed, Feb 11, 2015 at 09:11:59AM +0000, Peter Zijlstra wrote:
> > On Tue, Feb 10, 2015 at 08:48:36PM +0000, Mark Rutland wrote:
> > > From f390ccbb31f06efee49b4469943c8d85d963bfb5 Mon Sep 17 00:00:00 2001
> > > From: Mark Rutland <mark.rutland@arm.com>
> > > Date: Tue, 10 Feb 2015 20:14:33 +0000
> > > Subject: [PATCH] genirq: allow mixed IRQF_NO_SUSPEND requests
> > > 
> > > In some cases a physical IRQ line may be shared between devices from
> > > which we expect interrupts during suspend (e.g. timers) and those we do
> > > not (e.g. anything we cut the power to). Where a driver did not request
> > > the interrupt with IRQF_NO_SUSPEND, it's unlikely that it can handle
> > > being called during suspend, and it may bring down the system.
> > > 
> > > This patch adds logic to automatically mark the irqactions for these
> > > potentially unsafe handlers as disabled during suspend, leaving actions
> > > with IRQF_NO_SUSPEND enabled. If an interrupt is raised on a shared line
> > > during suspend, only the handlers requested with IRQF_NO_SUSPEND will be
> > > called. The handlers requested without IRQF_NO_SUSPEND will be skipped
> > > as if they had immediately returned IRQF_NONE.
> > > 
> > > Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
> > > Cc: Jason Cooper <jason@lakedaemon.net>
> > > Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
> > > Cc: Peter Zijlstra <peterz@infradead.org>
> > > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > > Cc: Thomas Gleixner <tglx@linutronix.de>
> > > Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> > 
> > Aw gawd.. not that again.
> 
> I agree this isn't pretty, but at least it doesn't require the HW
> description to know about Linux internals, and it can work for !DT
> systems.
> 
> I'm really not happy with placing Linux implementation details into
> DTBs.
> 
> > So Rafael and tglx went over this a few months ago I think:
> > 
> >   lkml.kernel.org/r/26580319.OZP7jvJnA9 at vostro.rjw.lan
> > 
> > is the last series I could find. Maybe Rafael can summarize?
> 
> I can't get at any commentary from that link, unfortunately.
> 
> Rafael?

Well, the commentary is not there, because both I and Thomas implicitly agreed
on one thing: We cannot add any suspend-related checks to the interrupt handling
hot path, because that will affect everyone including people who don't use
suspend at all and who *really* care about interrupt handling performance.

Rafael