On Wed, Feb 11, 2015 at 03:07:48PM +0000, Rafael J. Wysocki wrote: > On Wednesday, February 11, 2015 02:14:37 PM Mark Rutland wrote: > > On Wed, Feb 11, 2015 at 02:31:18PM +0000, Rafael J. Wysocki wrote: > > > 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@xxxxxxx> > > > > > > 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@xxxxxxxxxxxxxxxxxx> > > > > > > Cc: Jason Cooper <jason@xxxxxxxxxxxxxx> > > > > > > Cc: Nicolas Ferre <nicolas.ferre@xxxxxxxxx> > > > > > > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > > > > > > Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > > > > > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > > > > > > Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx> > > > > > > > > > > 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@xxxxxxxxxxxxxx > > > > > > > > > > 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. > > > > That's fair enough, and I'm happy to avoid that by other means. > > > > My fundamental objection(s) to the current approach is that we create a > > binding for a non-existent device that people will abuse without > > considering the consequences. All we will end up with is more DTBs > > containing the mux regardless of wether the drivers (or hardware) are > > actually safe with a shared line. > > That is a valid concern in my view. > > > So with the changes moves out of the hot-path (e.g. with shuffling > > to/from a suspended_actions list in the pm code), is there some issue > > that I have not considered? > > When we were reworking the handling of wakeup interrupts during the 3.18 > cycle, one of my proposals was to move the "suspended" irqactions to an > "inactive" list during suspend_device_irqs() and back during > resume_device_irqs(), but Thomas didn't like that approach. His main > argument was that it made the code in question overly complex which > was fair enough to me. I've just looked into that, and have a trivial implementation that's contained within kernel/irq/pm.c, but it assumes that during suspend nothing needs to modify actions. > What about adding a new flag like I said? That works for me. I'll respond in the other mail. Thanks, Mark. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
