linux-kernel - Re: Add IRQS_PENDING for nested and simple irq handler as well

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Message-ID: <CAH3Oq6T905+3fkF43NAMMFvJvq7dsk_so6T2vQ8ZJrA5xiU3YA@mail.gmail.com>
Date:	Tue, 22 May 2012 19:14:41 +0800
From:	Ning Jiang <ning.n.jiang@...il.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	rjw@...k.pl, linux-kernel@...r.kernel.org
Subject: Re: Add IRQS_PENDING for nested and simple irq handler as well

2012/5/22 Thomas Gleixner <tglx@...utronix.de>:
> On Tue, 22 May 2012, Ning Jiang wrote:
>
> Please do not top post.
>
>> Sorry that I do not make myself clear.
>>
>> First, we should keep all the handle_*_irq behave in pretty much the
>> same way even just for the beauty of it. Every interrupt disabled in
>> suspend operation needs the ability to abort suspend if there is a
>> pending irq.
>>
>> Second, let's take look at a example:
>>
>>               |
>>        +---------+
>>         |   INTC  |
>>        +---------+
>>                   |  GPIO_IRQ
>>             +------------+
>>              | gpio-exp  |
>>             +------------+
>>                |            |
>>    GPIO0_IRQ  GPIO1_IRQ
>>
>> In the above diagram, gpio expander has irq number GPIO_IRQ, it is
>> connected with two sub GPIO pins, GPIO0 and GPIO1.
>>
>> During suspend, normally we want to set IRQF_NO_SUSPEND for GPIO_IRQ
>> so that gpio expander driver can handle the sub irq GPIO0_IRQ and
>> GPIO1_IRQ, and these two irqs themselves are handled by simple or
>> nested irq in some drivers(typically gpio and mfd driver), if they are
>> disabled during suspend, we want them to be able to abort suspend too.
>
> Ok, that makes a lot of sense and should be part of the changelog, so
> we know in a year from now why we did this change. Care to resend with
> a fixed up changelog ?
>
> Thanks,
>
>        tglx

Thanks for your guidance on commit changelog. It's really helpful.
Here is the comments formatted patch, please help to review.


>From 40c31a11049726761fe5c7c629200f48950d4229 Mon Sep 17 00:00:00 2001
From: Ning Jiang <ning.n.jiang@...il.com>
Date: Tue, 22 May 2012 00:19:20 +0800
Subject: [PATCH] genirq: Add IRQS_PENDING for nested and simple irq
handler as well

We should keep all the handle_*_irq behave in pretty much the same
way even just for the beauty of it. Every interrupt disabled in
suspend operation needs the ability to abort suspend if there is a
pending irq.

Let's take look at an example:

            |
       +---------+
       |   INTC  |
       +---------+
               | GPIO_IRQ
            +------------+
            |  gpio-exp  |
            +------------+
              |        |
         GPIO0_IRQ  GPIO1_IRQ

In the above diagram, gpio expander has irq number GPIO_IRQ, it is
connected with two sub GPIO pins, GPIO0 and GPIO1.

During suspend, normally we want to set IRQF_NO_SUSPEND for GPIO_IRQ
so that gpio expander driver can handle the sub irq GPIO0_IRQ and
GPIO1_IRQ, and these two irqs themselves can further be handled by
simple or nested irq in some drivers(typically gpio and mfd driver).
If they are disabled during suspend and used as wakeup sources, we
want them to be able to abort suspend too.

Set IRQS_PENDING flag in handle_nested_irq() and handle_simple_irq()
when the irq is disabled will make check_wakeup_irqs() check for irqs
like GPIO0_IRQ and GPIO1_IRQ to abort suspend.

Signed-off-by: Ning Jiang <ning.n.jiang@...il.com>
---
 kernel/irq/chip.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 741f836..5bec667 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -275,8 +275,10 @@ void handle_nested_irq(unsigned int irq)
 	kstat_incr_irqs_this_cpu(irq, desc);

 	action = desc->action;
-	if (unlikely(!action || irqd_irq_disabled(&desc->irq_data)))
+	if (unlikely(!action || irqd_irq_disabled(&desc->irq_data))) {
+		desc->istate |= IRQS_PENDING;
 		goto out_unlock;
+	}

 	irqd_set(&desc->irq_data, IRQD_IRQ_INPROGRESS);
 	raw_spin_unlock_irq(&desc->lock);
@@ -324,8 +326,10 @@ handle_simple_irq(unsigned int irq, struct irq_desc *desc)
 	desc->istate &= ~(IRQS_REPLAY | IRQS_WAITING);
 	kstat_incr_irqs_this_cpu(irq, desc);

-	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);

-- 
1.7.1

Thanks,
Ning

Download attachment "0001-genirq-Add-IRQS_PENDING-for-nested-and-simple-irq-ha.patch" of type "application/octet-stream" (2481 bytes)