linux-kernel - Re: [PATCH] genirq: Clarify that irq wake state is orthogonal to enable/disable

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Date:   Wed, 5 Feb 2020 08:34:10 -0700
From:   Lina Iyer <ilina@...eaurora.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Stephen Boyd <swboyd@...omium.org>, linux-kernel@...r.kernel.org,
        Marc Zyngier <maz@...nel.org>,
        Douglas Anderson <dianders@...omium.org>,
        Maulik Shah <mkshah@...eaurora.org>
Subject: Re: [PATCH] genirq: Clarify that irq wake state is orthogonal to
 enable/disable

On Wed, Feb 05 2020 at 05:27 -0700, Thomas Gleixner wrote:
>Stephen Boyd <swboyd@...omium.org> writes:
>> There's some confusion around if an irq that's disabled with
>> disable_irq() can still wake the system from sleep states such as
>> "suspend to RAM". Let's clarify this in the kernel documentation for
>> irq_set_irq_wake() so that it's clear that an irq can be disabled and
>> still wake the system if it has been marked for wakeup.
>>
>> Cc: Marc Zyngier <maz@...nel.org>
>> Cc: Douglas Anderson <dianders@...omium.org>
>> Cc: Lina Iyer <ilina@...eaurora.org>
>> Cc: Maulik Shah <mkshah@...eaurora.org>
>> Signed-off-by: Stephen Boyd <swboyd@...omium.org>
>> ---
>>  kernel/irq/manage.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
>> index 818b2802d3e7..fa8db98c8699 100644
>> --- a/kernel/irq/manage.c
>> +++ b/kernel/irq/manage.c
>> @@ -731,6 +731,11 @@ static int set_irq_wake_real(unsigned int irq, unsigned int on)
>>   *
>>   *	Wakeup mode lets this IRQ wake the system from sleep
>>   *	states like "suspend to RAM".
>> + *
>> + *	Note: irq enable/disable state is completely orthogonal
>> + *	to the enable/disable state of irq wake. An irq can be
>> + *	disabled with disable_irq() and still wake the system as
>> + *	long as the irq has wake enabled.
>
>It clearly should say that this is really depending on the hardware
>implementation of the particual interrupt chip whether disabled + wake
>mode is supported.
>
Could an irqchip flag be used to warn users that we may not wakeup from
suspend/resume if the interrupt if the hardware does not support wakeup
when disabled ?

--Lina