linux-kernel - Re: [PATCH resend 2/2] [RFC] genirq: Set IRQCHIP_SKIP_SET_WAKE for no_irq_chip and dummy_irq

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Date:	Mon, 12 Jan 2015 08:37:29 -0800
From:	santosh shilimkar <santosh.shilimkar@...cle.com>
To:	Geert Uytterhoeven <geert+renesas@...der.be>,
	Linus Walleij <linus.walleij@...aro.org>,
	Alexandre Courbot <gnurou@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>
CC:	Santosh Shilimkar <ssantosh@...nel.org>,
	linux-gpio@...r.kernel.org, linux-sh@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH resend 2/2] [RFC] genirq: Set IRQCHIP_SKIP_SET_WAKE for
 no_irq_chip and dummy_irq_chip

On 1/12/2015 8:04 AM, Geert Uytterhoeven wrote:
> If no_irq_chip or dummy_irq_chip are used for wake up (e.g. gpio-keys
> with a simple GPIO controller), the following warning is printed on
> resume from s2ram:
>
>      WANING: CPU: 0 PID: 1046 at kernel/irq/manage.c:537 irq_set_irq_wake+0x9c/0xf8()
>      Unbalanced IRQ 113 wake disable
>
> This happens because no_irq_chip and dummy_irq_chip do not implement
> irq_chip.irq_set_wake(), causing set_irq_wake_real() to return -ENXIO,
> and irq_set_irq_wake() to reset the wake_depth to zero.
>
> Set IRQCHIP_SKIP_SET_WAKE to indicate that irq_chip.irq_set_wake() is
> not implemented.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
> ---
> Alternatively, can't we remove IRQCHIP_SKIP_SET_WAKE, and just check for
> the presence of irq_chip.irq_set_wake()?
> I'll be happy to send a patch to do that instead...
>
> Is there anything that relies on this -ENXIO error code?
> All irq_chip implementations that set IRQCHIP_SKIP_SET_WAKE do not
> implement irq_chip.irq_set_wake(). There are probably more of them that
> forgot to set IRQCHIP_SKIP_SET_WAKE though.
> Am I missing something?
> Commit 60f96b41f71d2a13 ("genirq: Add IRQCHIP_SKIP_SET_WAKE flag")
> doesn't explain why adding the flag was chosen.
>
The flag was added to avoid dummy irq_set_wake() implementation
as described in the commit.

------------------
commit 60f96b41f71d2a13d1c0a457b8b77958f77142d1
Author: Santosh Shilimkar <santosh.shilimkar@...com>
Date:   Fri Sep 9 13:59:35 2011 +0530

     genirq: Add IRQCHIP_SKIP_SET_WAKE flag

     Some irq chips need the irq_set_wake() functionality, but do not
     require a irq_set_wake() callback. Instead of forcing an empty
     callback to be implemented add a flag which notes this fact. Check for
     the flag in set_irq_wake_real() and return success when set.

     Signed-off-by: Santosh Shilimkar <santosh.shilimkar@...com>
     Cc: Thomas Gleixner <tglx@...utronix.de>
------------------

Here is the relevant thread.
http://lists.infradead.org/pipermail/linux-arm-kernel/2011-September/064590.html

As you can read from thread, the idea is to handle the need at
genirq level. Either with a flag or a dummy function.

Hope this helps.

Regards,
Santosh

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