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

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Date: Thu, 29 Feb 2024 20:31:20 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Qingliang Li (黎晴亮) <Qingliang.Li@...iatek.com>
Cc: "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>, 
	"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, Feb 28, 2024 at 9:33 AM Qingliang Li (黎晴亮)
<Qingliang.Li@...iatek.com> wrote:
>
> 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.

It would be good to put the above information into the patch
changelog, as it actually explains the problem.

Thanks!