linux-kernel - Re: [PATCH] PM: wakeirq: fix wake irq warning in system suspend stage

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Message-ID: <0c1e972cf506b22cb1de73c8509bf2b917c0806b.camel@mediatek.com>
Date: Wed, 28 Feb 2024 08:33:40 +0000
From: Qingliang Li (黎晴亮) <Qingliang.Li@...iatek.com>
To: "johan+linaro@...nel.org" <johan+linaro@...nel.org>, "d-gole@...com"
	<d-gole@...com>, "pavel@....cz" <pavel@....cz>, "gregkh@...uxfoundation.org"
	<gregkh@...uxfoundation.org>, "tony@...mide.com" <tony@...mide.com>,
	"len.brown@...el.com" <len.brown@...el.com>, "rafael@...nel.org"
	<rafael@...nel.org>, "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
	"angelogioacchino.delregno@...labora.com"
	<angelogioacchino.delregno@...labora.com>,
	Axe Yang (杨磊) <Axe.Yang@...iatek.com>
CC: "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-mediatek@...ts.infradead.org"
	<linux-mediatek@...ts.infradead.org>, "linux-pm@...r.kernel.org"
	<linux-pm@...r.kernel.org>
Subject: Re: [PATCH] PM: wakeirq: fix wake irq warning in system suspend stage

On Wed, 2024-02-28 at 11:34 +0530, Dhruva Gole wrote:
>  	 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>  Hi,
> 
> On 28/02/24 07:30, Qingliang Li wrote:
> > When driver registers the wake irq with reverse enable ordering,
> > the wake irq will be re-enabled when entering system suspend,
> triggering
> > an 'Unbalanced enable for IRQ xxx' warning. The wake irq will be
> > enabled in both dev_pm_enable_wake_irq_complete() and
> dev_pm_arm_wake_irq()
> > 
> > To fix this issue, complete the setting of
> WAKE_IRQ_DEDICATED_ENABLED flag
> > in dev_pm_enable_wake_irq_complete() to avoid redundant irq
> enablement.
> 
> 
> Just trying to understand, why not in dev_pm_arm_wake_irq ?
> Is it cuz it's called much after dev_pm_enable_wake_irq_complete ?
> Not sure what's the exact call order, but I am assuming
> dev_pm_enable_wake_irq_complete is more of a runtime thing and
> dev_pm_arm_wake_irq happens finally at system suspend?

You are right, the involvement of 'dev_pm_enable_wake_irq_complete' is
due to the driver selecting 'pm_runtime_force_suspend' as the callback
function for system suspend. In this scenario, the call sequence during
system suspend is as follows:
dpm_suspend_start -> dpm_run_callback -> pm_runtime_force_suspend ->
dev_pm_enable_wake_irq_check/complete
suspend_enter -> dpm_suspend_noirq -> dev_pm_arm_wake_irq

Based on the above, if the driver (i) chooses pm_runtime_force_suspend
as the system suspend callback function and (ii) registers wake irq
with reverse enable ordering, the wake irq will be enabled twice during
system suspend.

> 
> > 
> > Fixes: 8527beb12087 ("PM: sleep: wakeirq: fix wake irq arming")
> > Signed-off-by: Qingliang Li <qingliang.li@...iatek.com>
> > ---
> 
> $subject: Most recent convention used for this file is:
> "PM: sleep: wakeirq:  ..."

I'm sorry, but what is the problem with the description of the "Fixed"
field? I didn't get your point and I wrote it according to the previous
patches.

> 
> >   drivers/base/power/wakeirq.c | 4 +++-
> >   1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/base/power/wakeirq.c
> b/drivers/base/power/wakeirq.c
> > index 42171f766dcb..5a5a9e978e85 100644
> > --- a/drivers/base/power/wakeirq.c
> > +++ b/drivers/base/power/wakeirq.c
> > @@ -313,8 +313,10 @@ void dev_pm_enable_wake_irq_complete(struct
> device *dev)
> >   return;
> >   
> >   if (wirq->status & WAKE_IRQ_DEDICATED_MANAGED &&
> > -    wirq->status & WAKE_IRQ_DEDICATED_REVERSE)
> > +    wirq->status & WAKE_IRQ_DEDICATED_REVERSE) {
> >   enable_irq(wirq->irq);
> > +wirq->status |= WAKE_IRQ_DEDICATED_ENABLED;
> > +}
> 
> But this does make sense to make sure status is updated,
> You can pick my R-by.
> 
> Reviewed-by: Dhruva Gole <d-gole@...com>
> 
> -- 
> Thanks and Regards,
> Dhruva Gole