Re: [PATCH 2/3] IRQ: allow check_wakeup_irqs to notice level-triggered interrupts.

[NeilBrown]

On Wed, 25 Apr 2012 14:54:54 +0200 (CEST) Thomas Gleixner
<t...@linutronix.de> wrote:

> Why not simply managing the pending bit for level irqs ?
> 

Hi Thomas,
 thanks again for the patch.  I finally made time to test it and it works as
expected.  I've included it below with a change-log entry and tested-by:
in case that helps.

Thanks,
NeilBrown


From: Thomas Gleixner <t...@linutronix.de>
Date: Wed, 25 Apr 2012 12:54:54 +0200
Subject: [PATCH] IRQ: allow check_wakeup_irqs to notice level-triggered 
interrupts.

Level triggered interrupts do not cause IRQS_PENDING to be set when
they fire-while-disabled as the 'pending' state is always present in
the level - they automatically refire where re-enabled.

However the IRQS_PENDING flag is also used to abort a suspend cycle -
if any 'is_wakeup_set' interrupt is PENDING, check_wakeup_irqs() will
cause suspend to abort. Without IRQS_PENDING, suspend won't abort.

Consequently, level-triggered interrupts that fire during the 'noirq'
phase of suspend do not currently abort suspend.

So set IRQS_PENDING even for level triggered interrupts, and make sure
to clear the flag in check_irq_resend.

Also: in check_wakeup_irqs, ignore 'is_wakeup' interrupts that were
already disabled before suspend_device_irqs() disabled them further.

Tested-by: NeilBrown <ne...@suse.de>

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 6080f6b..741f836 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -379,8 +379,10 @@ handle_level_irq(unsigned int irq, struct irq_desc *desc)
         * If its disabled or no action available
         * keep it masked and get out of here
         */
-       if (unlikely(!desc->action || irqd_irq_disabled(&desc->irq_data)))
+       if (unlikely(!desc->action || irqd_irq_disabled(&desc->irq_data))) {
+               desc->istate |= IRQS_PENDING;
                goto out_unlock;
+       }
 
        handle_irq_event(desc);
 
diff --git a/kernel/irq/pm.c b/kernel/irq/pm.c
index 15e53b1..b858ce3 100644
--- a/kernel/irq/pm.c
+++ b/kernel/irq/pm.c
@@ -103,7 +103,8 @@ int check_wakeup_irqs(void)
        int irq;
 
        for_each_irq_desc(irq, desc) {
-               if (irqd_is_wakeup_set(&desc->irq_data)) {
+               if (desc->depth == 1 &&
+                   irqd_is_wakeup_set(&desc->irq_data)) {
                        if (desc->istate & IRQS_PENDING)
                                return -EBUSY;
                        continue;
diff --git a/kernel/irq/resend.c b/kernel/irq/resend.c
index 14dd576..6454db7 100644
--- a/kernel/irq/resend.c
+++ b/kernel/irq/resend.c
@@ -58,10 +58,13 @@ void check_irq_resend(struct irq_desc *desc, unsigned int 
irq)
        /*
         * We do not resend level type interrupts. Level type
         * interrupts are resent by hardware when they are still
-        * active.
+        * active. Clear the pending bit so suspend/resume does not
+        * get confused.
         */
-       if (irq_settings_is_level(desc))
+       if (irq_settings_is_level(desc)) {
+               desc->istate &= ~IRQS_PENDING;
                return;
+       }
        if (desc->istate & IRQS_REPLAY)
                return;
        if (desc->istate & IRQS_PENDING) {

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