linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Thomas Gleixner <tglx@linutronix.de>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Linux PM list <linux-pm@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux PCI <linux-pci@vger.kernel.org>,
	Dmitry Torokhov <dtor@google.com>,
	Aubrey Li <aubrey.li@intel.com>
Subject: Re: [PATCH 2/5 v3] irq / PM: Make wakeup interrupts work with suspend-to-idle
Date: Wed, 27 Aug 2014 22:32:23 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.10.1408272130350.3323@nanos> (raw)
In-Reply-To: <16387974.EqoNYrShmO@vostro.rjw.lan>

On Wed, 27 Aug 2014, Rafael J. Wysocki wrote:
> The line of reasoning leading to that is as follows.
> 
> The way suspend_device_irqs() works and the existing code in
> check_wakeup_irqs(), called by syscore_suspend(), imply that:
> 
>   (1) Interrupt handlers are not invoked for wakeup interrupts
>       after suspend_device_irqs().
> 
>   (2) All interrups from system wakeup IRQs received after\
>       suspend_device_irqs() cause full system suspends to be aborted.
> 
> In addition to the above, there is the requirement that
> 
>   (3) System wakeup interrupts should wake up the system from
>       suspend-to-idle.
> 
> It immediately follows from (1) and (2) that no effort is made to
> distinguish "genuine" wakeup interrupts from "spurious" ones.  They
> all are treated in the same way.  Since (3) means that "genuine"
> wakeup interrupts are supposed to wake up the system from
> suspend-to-idle too, consistency with (1) and (2) requires that
> "spurious" wakeup interrupts should do the same thing.  Thus there is
> no reason to invoke interrupt handlers for wakeup interrups after
> suspend_device_irqs() in the suspend-to-idle case.  Moreover, doing
> so would go against rule (1).

I agree with that, but I disagree with the implementation.

We now have two separate mechanisms to abort suspend:

1) The existing suspend_device_irqs() / check_wakeup_irqs() 

2) The new suspend_device_irqs() /
   reenable_stuff_and_fiddle_with_irq_action()

So why do we need those two mechanisms in the first place?

AFAICT there is no reason why we cant use the abort_suspend mechanics
to replace the suspend_device_irqs() / check_wakeup_irqs() pair.

All it needs is to do the handler substitution in
suspend_device_irqs() right away and replace the loop in
check_wakeup_irqs() with a check for abort_suspend == true. The roll
back of the handler substitution can happen in resume_device_irqs()
for both scenarios.

Aside of that the whole irqaction based substitution is silly. What's
wrong with doing it at the real interrupt handler level?

static void handle_wakeup_irq(unsigned int irq, struct irq_desc *desc)
{
	raw_spin_lock(&desc->lock);

	desc->istate |= IRQS_SUSPENDED | IRQS_PENDING;
	desc->depth++;
	irq_disable(desc);
	pm_system_wakeup();

	raw_spin_unlock(&desc->lock);
}

void suspend_device_irqs(void)
{
	for_each_irq_desc(irq, desc) {
		/* Disable the interrupt unconditionally */	       
		disable_irq(irq);

		/* Is the irq a wakeup source? */
		if (!irqd_is_wakeup_set(&desc->irq_data))
			continue;

		/* Replace the handler */
		raw_spin_lock_irqsave(&desc->lock, flags);
	     	desc->saved_handler = desc->handler;
		desc->handler = handle_wakeup_irq;
		raw_spin_unlock_irqrestore(&desc->lock, flags);

		/* Reenable the wakeup irq */
		enable_irq(irq);
	}
}

/* Move that into the pm core code */
bool check_wakeup_irqs(void)
{
	return abort_suspend;
}

void resume_device_irqs(void)
{
	for_each_irq_desc(irq, desc) {

		/* Prevent the wakeup handler from running */
		disable_irq();

		raw_spin_lock_irqsave(&desc->lock, flags);

		/* Do we need to restore the handler? */
		if (desc->handler == handle_wakeup_irq)
		   	desc->handler = desc->saved_handler;

		/* Is the irq a wakeup source? */
		if (!irqd_is_wakeup_set(&desc->irq_data))
		   	__enable_irq(irq, desc);

		/* Did it get disabled in the wakeup handler? */
		else if (desc->istate & IRQS_SUSPENDED)
		   	__enable_irq(irq, desc);

		raw_spin_unlock_irqrestore(&desc->lock, flags);

		enable_irq();
	}
}

Hmm?

One thing we might think about is having flow specific
handle_wakeup_irq variants as some hardware might require an ack or
eoi, but that's a simple to solve problem and way simpler than
fiddling with the irqaction chain and avoids the whole mess of
sprinkling irq_pm_saved_id() and irq_pm_restore_handler() calls all
over the place. I wonder why you added them to __free_irq() at all,
but no, we dont want that.

Thanks,

	tglx



  reply	other threads:[~2014-08-27 20:32 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-08-11 13:56 [PATCH 0/6 v2] irq / PM: Shared IRQs vs IRQF_NO_SUSPEND and suspend-to-idle wakeup interrupts Rafael J. Wysocki
2014-08-11 13:58 ` [PATCH 1/6 v2] PM / sleep: Mechanism for aborting system suspends unconditionally Rafael J. Wysocki
2014-08-11 13:59 ` [PATCH 2/6 v2] irq / PM: Make IRQF_NO_SUSPEND work with shared interrupts Rafael J. Wysocki
2014-08-11 14:00 ` [PATCH 3/6 v2] irq / PM: Make wakeup interrupts work with suspend-to-idle Rafael J. Wysocki
2014-08-11 14:01 ` [PATCH 4/6 v2] x86 / PM: Set IRQCHIP_SKIP_SET_WAKE for IOAPIC IRQ chip objects Rafael J. Wysocki
2014-08-11 14:02 ` [PATCH 5/6 v2] PCI / PM: Make PCIe PME interrupts wake up from suspend-to-idle Rafael J. Wysocki
2014-08-11 14:03 ` [PATCH 6/6 v2] irq / PM: Document rules related to system suspend and interrupts Rafael J. Wysocki
2014-08-26 23:46 ` [PATCH 0/5 v3] irq / PM: Suspend-to-idle wakeup interrupts Rafael J. Wysocki
2014-08-26 23:47   ` [PATCH 1/5 v3] PM / sleep: Mechanism for aborting system suspends unconditionally Rafael J. Wysocki
2014-08-26 23:49   ` [PATCH 2/5 v3] irq / PM: Make wakeup interrupts work with suspend-to-idle Rafael J. Wysocki
2014-08-27 20:32     ` Thomas Gleixner [this message]
2014-08-27 22:51       ` Rafael J. Wysocki
2014-08-28  9:23         ` Thomas Gleixner
2014-08-29  1:51           ` Rafael J. Wysocki
2014-08-26 23:50   ` [PATCH 3/5 v3] x86 / PM: Set IRQCHIP_SKIP_SET_WAKE for IOAPIC IRQ chip objects Rafael J. Wysocki
2014-08-26 23:51   ` [PATCH 4/5 v3] PCI / PM: Make PCIe PME interrupts wake up from suspend-to-idle Rafael J. Wysocki
2014-08-26 23:52   ` [PATCH 5/5 v3] irq / PM: Document rules related to system suspend and interrupts Rafael J. Wysocki
2014-08-28 22:44   ` [PATCH 0/5 v3] irq / PM: Suspend-to-idle wakeup interrupts Thomas Gleixner
2014-08-29  0:54     ` Rafael J. Wysocki
2014-08-29  1:09       ` Thomas Gleixner
2014-09-01 14:18   ` [PATCH 00/13] genirq / PM: Wakeup interrupts handling rework (related to suspend-to-idle) Rafael J. Wysocki
2014-09-01 14:19     ` [PATCH 01/13] PM / sleep: Mechanism for aborting system suspends unconditionally Rafael J. Wysocki
2014-09-01 14:20     ` [PATCH 02/13] genirq: Move suspend/resume logic into irq/pm code Rafael J. Wysocki
2014-09-01 14:21     ` [PATCH 03/13] genirq: Add sanity checks for PM options on shared interrupt lines Rafael J. Wysocki
2014-09-01 14:22     ` [PATCH 04/13] genirq: Make use of pm misfeature accounting Rafael J. Wysocki
2014-09-01 14:22     ` [PATCH 05/13] genirq: Move MASK_ON_SUSPEND handling into suspend_device_irqs() Rafael J. Wysocki
2014-09-01 14:23     ` [PATCH 06/13] genirq: Avoid double loop on suspend Rafael J. Wysocki
2014-09-01 14:24     ` [PATCH 07/13] genirq: Distangle edge handler entry Rafael J. Wysocki
2014-09-01 14:24     ` [PATCH 08/13] genirq: Create helper for flow handler entry check Rafael J. Wysocki
2014-09-01 14:26     ` [PATCH 09/13] genirq: Mark wakeup sources as armed on suspend Rafael J. Wysocki
2014-09-01 14:27     ` [PATCH 10/13] genirq: Simplify wakeup mechanism Rafael J. Wysocki
2014-09-01 14:28     ` [PATCH 11/13] x86 / PM: Set IRQCHIP_SKIP_SET_WAKE for IOAPIC IRQ chip objects Rafael J. Wysocki
2014-09-01 14:28     ` [PATCH 12/13] PCI / PM: Make PCIe PME interrupts wake up from suspend-to-idle Rafael J. Wysocki
2014-09-01 14:29     ` [PATCH 13/13] PM / genirq: Document rules related to system suspend and interrupts Rafael J. Wysocki

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=alpine.DEB.2.10.1408272130350.3323@nanos \
    --to=tglx@linutronix.de \
    --cc=aubrey.li@intel.com \
    --cc=dtor@google.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pci@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=peterz@infradead.org \
    --cc=rjw@rjwysocki.net \
    --subject='Re: [PATCH 2/5 v3] irq / PM: Make wakeup interrupts work with suspend-to-idle' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).