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

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Date: Wed, 28 Feb 2024 14:28:11 +0530
From: Dhruva Gole <d-gole@...com>
To: Qingliang Li (黎晴亮) <Qingliang.Li@...iatek.com>,
        "johan+linaro@...nel.org" <johan+linaro@...nel.org>,
        "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

Hello,

On 28/02/24 14:03, Qingliang Li (黎晴亮) 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

OK this is what I expected, thanks for clarifying!

> 
> 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.

Yep, makes sense

> 
>>
>>>
>>> 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.

I am not talking about your "Fixed", I am taking about the subject line
of the patch.
You've used "PM: wakeirq: fix wake ..."

Instead use
"PM: sleep: wakeirq: fix wake ..."

No strong objections here, it's just a nit.

[..snip..]

-- 
Thanks and Regards,
Dhruva Gole