From: Boris Brezillon <boris.brezillon@free-electrons.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Thomas Gleixner <tglx@linutronix.de>,
Jason Cooper <jason@lakedaemon.net>,
Nicolas Ferre <nicolas.ferre@atmel.com>,
Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>,
Alexandre Belloni <alexandre.belloni@free-electrons.com>,
Rob Herring <robh+dt@kernel.org>, Pawel Moll <Pawel.Moll@arm.com>,
Ian Campbell <ijc+devicetree@hellion.org.uk>,
Kumar Gala <galak@codeaurora.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 3/5] irqchip: Add DT binding doc for the virtual irq demuxer chip
Date: Mon, 23 Feb 2015 21:16:22 +0100 [thread overview]
Message-ID: <20150223211622.37cf3ca1@bbrezillon> (raw)
In-Reply-To: <20150223181448.GQ9714@leverpostej>
On Mon, 23 Feb 2015 18:14:48 +0000
Mark Rutland <mark.rutland@arm.com> wrote:
[...]
> > This is because irq_may_run [1], which is called to decide whether we
> > should handle this irq or just wake the system up [2], will always
> > return true if at least one of the shared action has tagged the irq
> > line as a wakeup source.
>
> I assume you mean we return false in this case (having triggered the
> wakeup within irq_pm_check_wakeup, which returned true), but otherwise
> agreed.
Yep, I meant 'return false'.
>
> I can envisage problems if the irq handler of a wakeup device can't be
> run safely until resume time, though I'm not sure if that happens in
> practice given the device is necessarily going to be active.
Isn't that the purpose of the
IRQF_NO_SUSPEND_SAFE/IRQF_SHARED_TIMER_OK/IRQF_SHARED_WAKEUP_SIBLING_OK
flag ?
>
> > Sorry for summarizing things you most likely already know, but I want
> > to be sure I'm actually understanding it correctly.
> >
> > Now, let's look at how this could be solved.
> > Here is a proposal [3] that does the following:
>
> This would be a lot easier to follow/review as an RFC post to the
> mailing list.
Yep, that was the plan, just wanted to make sure I had correctly
understood the problem before posting an RFC.
> Otherwise I have some high-level comments on the stuff
> below, which I think matches the shape of what we discussed on IRC.
>
> > 1/ prevent a system wakeup when at least one of the action handler
> > has set the IRQF_NO_SUSPEND flag
>
> We might need to add some logic to enable_irq_wake and
> irq_pm_install_action to prevent some of the horrible mismatch cases we
> can get here (e.g. if we have a wakeup handler, a IRQF_NO_SUSPEND
> handler, and another handler which is neither). We may need to
> reconsider temporarily stashing the other potential interrupts.
Actually if we force users to pass the IRQF_XXX_SAFE (I'm tired writing
all the potential names :-)), when mixing IRQF_NO_SUSPEND
and !IRQF_NO_SUSPEND handlers, we shouldn't bother deactivating normal
handlers (those without IRQF_NO_SUSPEND), 'cause they claimed they could
safely be called in suspended state.
>
> Do we perhaps need an IRQF_SHARED_WAKEUP_SIBLING_OK for timer drivers to
> assert their handlers are safe for the whole suspend period rather than
> just the period they expect to be enabled for? Or do those always
> happen to be safe in practice?
I thought they were always safe...
>
> > 2/ Add a few helpers to deal with system wakeup from drivers code
>
> The irq_pm_force_wakeup part looks like what I had in mind.
>
> > 3/ Rework the at91 RTC driver to show how such weird cases could be
> > handled
>
> It might be simpler to do this with a PM notifier within the driver
> rather than having to traverse all the irq_descs, though perhaps not.
I'm not sure to understand that one. Where am I traversing irq_descs
(irq_to_desc, which is called when testing wakeup_armed status, is a
direct table indexing operation) ?
Moreover, I'm not sure when the PM_POST_SUSPEND event is sent, and
testing the WAKEUP_ARMED flag should be safe in all cases, right ?
>
> > Of course, I'll need the IRQF_SHARED_TIMER_OK patch to prevent the
> > WARN_ON backtrace.
>
> That should be fine; it's backed up in the list archive ;)
>
> > Please, let me know if I missed anything important, share your opinion
> > on this proposal, and feel free to propose any other solution.
>
> Hopefully the above covers that!
Yes it does.
Thanks for the review.
Best Regards,
Boris
--
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
next prev parent reply other threads:[~2015-02-23 20:16 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-29 10:33 [PATCH v4 0/5] ARM: at91: fix irq_pm_install_action WARNING Boris Brezillon
2015-01-29 10:33 ` [PATCH v4 1/5] genirq: Authorize chained handlers to remain disabled when initialized Boris Brezillon
2015-01-29 10:33 ` [PATCH v4 2/5] irqchip: add virtual demultiplexer implementation Boris Brezillon
2015-02-10 15:00 ` Peter Zijlstra
2015-02-10 15:20 ` Boris Brezillon
2015-02-10 15:43 ` [PATCH] genirq: fix virtual irq demuxer related comments Boris Brezillon
2015-02-10 16:14 ` Peter Zijlstra
2015-02-20 16:12 ` Mark Rutland
2015-02-20 16:17 ` Peter Zijlstra
2015-02-10 15:48 ` [PATCH v4 2/5] irqchip: add virtual demultiplexer implementation Mark Rutland
2015-01-29 10:33 ` [PATCH v4 3/5] irqchip: Add DT binding doc for the virtual irq demuxer chip Boris Brezillon
2015-02-10 15:36 ` Mark Rutland
2015-02-10 15:52 ` Boris Brezillon
2015-02-10 16:06 ` Boris Brezillon
2015-02-10 16:16 ` Mark Rutland
2015-02-10 16:20 ` Boris Brezillon
2015-02-10 20:48 ` Mark Rutland
2015-02-11 8:53 ` Boris Brezillon
2015-02-11 11:11 ` Mark Rutland
2015-02-11 12:24 ` Boris Brezillon
2015-02-11 12:36 ` Mark Rutland
2015-02-11 13:38 ` Alexandre Belloni
2015-02-11 13:48 ` Mark Rutland
2015-02-11 14:55 ` Rafael J. Wysocki
2015-02-11 14:43 ` Mark Rutland
2015-02-11 15:17 ` Rafael J. Wysocki
2015-02-11 15:03 ` Boris Brezillon
2015-02-11 15:39 ` Rafael J. Wysocki
2015-02-11 15:23 ` Mark Rutland
2015-02-11 15:12 ` Mark Rutland
2015-02-11 15:51 ` Rafael J. Wysocki
2015-02-11 15:57 ` Mark Rutland
2015-02-11 16:15 ` Boris Brezillon
2015-02-11 16:32 ` Mark Rutland
2015-02-11 16:38 ` Boris Brezillon
2015-02-11 17:17 ` Mark Rutland
2015-02-20 14:22 ` Mark Rutland
2015-02-20 14:53 ` Boris Brezillon
2015-02-20 15:16 ` Mark Rutland
2015-02-23 17:00 ` Boris Brezillon
2015-02-23 18:14 ` Mark Rutland
2015-02-23 20:16 ` Boris Brezillon [this message]
2015-02-11 16:42 ` Rafael J. Wysocki
2015-02-11 16:28 ` Boris Brezillon
2015-02-11 17:13 ` Mark Rutland
2015-02-11 17:29 ` Boris Brezillon
2015-02-12 10:52 ` Mark Rutland
2015-02-12 11:09 ` Boris Brezillon
2015-02-12 11:23 ` Mark Rutland
2015-02-16 9:49 ` Peter Zijlstra
2015-02-16 9:28 ` Peter Zijlstra
2015-02-16 12:23 ` Mark Rutland
2015-02-19 1:16 ` Rafael J. Wysocki
2015-02-19 11:23 ` Mark Rutland
2015-02-19 22:35 ` Rafael J. Wysocki
2015-02-20 10:31 ` Mark Rutland
2015-02-24 1:02 ` Rafael J. Wysocki
2015-02-24 8:42 ` Boris Brezillon
2015-02-11 14:45 ` Boris Brezillon
2015-02-11 14:39 ` Rafael J. Wysocki
2015-02-11 9:11 ` Peter Zijlstra
2015-02-11 11:15 ` Mark Rutland
2015-02-11 14:31 ` Rafael J. Wysocki
2015-02-11 14:14 ` Mark Rutland
2015-02-11 15:07 ` Rafael J. Wysocki
2015-02-11 15:03 ` Mark Rutland
2015-02-11 14:34 ` Rafael J. Wysocki
2015-01-29 10:33 ` [PATCH v4 4/5] ARM: at91/dt: select VIRT_IRQ_DEMUX for all at91 SoCs Boris Brezillon
2015-01-29 10:33 ` [PATCH v4 5/5] ARM: at91/dt: define a virtual irq demultiplexer chip connected on irq1 Boris Brezillon
2015-02-09 15:47 ` [PATCH v4 0/5] ARM: at91: fix irq_pm_install_action WARNING Boris Brezillon
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