From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH] genirq: describe IRQF_COND_SUSPEND Date: Wed, 04 Mar 2015 22:55:58 +0100 Message-ID: <1456688.7sJdoQH1ZM@vostro.rjw.lan> References: <1424771762-16343-1-git-send-email-boris.brezillon@free-electrons.com> <20150304194246.GF22156@leverpostej> <20150304200040.GA12126@leverpostej> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7Bit Return-path: Received: from v094114.home.net.pl ([79.96.170.134]:64947 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751207AbbCDVcX (ORCPT ); Wed, 4 Mar 2015 16:32:23 -0500 In-Reply-To: <20150304200040.GA12126@leverpostej> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Mark Rutland Cc: Boris Brezillon , Peter Zijlstra , Thomas Gleixner , Jason Cooper , "linux-kernel@vger.kernel.org" , Nicolas Ferre , Jean-Christophe Plagniol-Villard , Alexandre Belloni , "linux-arm-kernel@lists.infradead.org" , Linux PM list On Wednesday, March 04, 2015 08:00:40 PM Mark Rutland wrote: > With certain restrictions it is possible for a wakeup device to share > and IRQ with an IRQF_NO_SUSPEND user, and the warnings introduced by > commit cab303be91dc47942bc25de33dc1140123540800 are spurious. The new > IRQF_COND_SUSPEND flag allows drivers to tell the core when these > restrictions are met, allowing spurious warnings to be silenced. > > This patch documents how IRQF_COND_SUSPEND is expected to be used, > updating some of the text now made invalid by its addition. > > Signed-off-by: Mark Rutland > Cc: Boris Brezillon > Cc: Peter Zijlstra > Cc: Rafael J. Wysocki > --- > Documentation/power/suspend-and-interrupts.txt | 16 +++++++++++++--- > 1 file changed, 13 insertions(+), 3 deletions(-) > > As promised previously, take IRQF_COND_SUSPEND into account in the > documentation. > > Rafael, does this look OK to you? Yes, it does, thanks! I'll queue it up along with the rest of the IRQF_COND_SUSPEND patches. > diff --git a/Documentation/power/suspend-and-interrupts.txt b/Documentation/power/suspend-and-interrupts.txt > index 50493c9..8afb29a 100644 > --- a/Documentation/power/suspend-and-interrupts.txt > +++ b/Documentation/power/suspend-and-interrupts.txt > @@ -112,8 +112,9 @@ any special interrupt handling logic for it to work. > IRQF_NO_SUSPEND and enable_irq_wake() > ------------------------------------- > > -There are no valid reasons to use both enable_irq_wake() and the IRQF_NO_SUSPEND > -flag on the same IRQ. > +There are very few valid reasons to use both enable_irq_wake() and the > +IRQF_NO_SUSPEND flag on the same IRQ, and it is never valid to use both for the > +same device. > > First of all, if the IRQ is not shared, the rules for handling IRQF_NO_SUSPEND > interrupts (interrupt handlers are invoked after suspend_device_irqs()) are > @@ -122,4 +123,13 @@ handlers are not invoked after suspend_device_irqs()). > > Second, both enable_irq_wake() and IRQF_NO_SUSPEND apply to entire IRQs and not > to individual interrupt handlers, so sharing an IRQ between a system wakeup > -interrupt source and an IRQF_NO_SUSPEND interrupt source does not make sense. > +interrupt source and an IRQF_NO_SUSPEND interrupt source does not generally > +make sense. > + > +In rare cases an IRQ can be shared between a wakeup device driver and an > +IRQF_NO_SUSPEND user. In order for this to be safe, the wakeup device driver > +must be able to discern spurious IRQs from genuine wakeup events (signalling > +the latter to the core with pm_system_wakeup()), must use enable_irq_wake() to > +ensure that the IRQ will function as a wakeup source, and must request the IRQ > +with IRQF_COND_SUSPEND to tell the core that it meets these requirements. If > +these requirements are not met, it is not valid to use IRQF_COND_SUSPEND. > -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.