linux-kernel - Re: [PATCH v3 1/5] PM: sleep: Resume children after resuming the parent

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Message-ID: <7186da1f-4d16-48f5-bdc0-cb04942b3a5e@linaro.org>
Date: Mon, 14 Jul 2025 11:35:56 +0100
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: Linux PM <linux-pm@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
 Alan Stern <stern@...land.harvard.edu>, Ulf Hansson
 <ulf.hansson@...aro.org>, Johan Hovold <johan@...nel.org>,
 Jon Hunter <jonathanh@...dia.com>, Saravana Kannan <saravanak@...gle.com>,
 William McVicker <willmcvicker@...gle.com>,
 Peter Griffin <peter.griffin@...aro.org>,
 André Draszik <andre.draszik@...aro.org>
Subject: Re: [PATCH v3 1/5] PM: sleep: Resume children after resuming the
 parent



On 7/14/25 8:29 AM, Rafael J. Wysocki wrote:
>> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
>> index d9d4fc58bc5a..0e186bc38a00 100644
>> --- a/drivers/base/power/main.c
>> +++ b/drivers/base/power/main.c
>> @@ -1281,6 +1281,27 @@ static void dpm_async_suspend_parent(struct device *dev, async_func_t func)
>>                 dpm_async_with_cleanup(dev->parent, func);
>>  }
>>
>> +static void dpm_async_suspend_complete_all(struct list_head *device_list)
>> +{
>> +       struct device *dev;
>> +
>> +
>> +       pr_err("tudor: %s: enter\n", __func__);
>> +       guard(mutex)(&async_wip_mtx);
>> +
>> +       list_for_each_entry_reverse(dev, device_list, power.entry) {
>> +               /*
>> +                * In case the device is being waited for and async processing
>> +                * has not started for it yet, let the waiters make progress.
>> +                */
>> +               pr_err("tudor: %s: in device list\n", __func__);
>> +               if (!dev->power.work_in_progress) {
>> +                       pr_err("tudor: %s: call complete_all\n", __func__);
>> +                       complete_all(&dev->power.completion);
>> +               }
>> +       }
>> +}
>> +
>>  /**
>>   * resume_event - Return a "resume" message for given "suspend" sleep state.
>>   * @sleep_state: PM message representing a sleep state.
>> @@ -1459,6 +1480,7 @@ static int dpm_noirq_suspend_devices(pm_message_t state)
>>                 mutex_lock(&dpm_list_mtx);
>>
>>                 if (error || async_error) {
>> +                       dpm_async_suspend_complete_all(&dpm_late_early_list);
>>                         /*
>>                          * Move all devices to the target list to resume them
>>                          * properly.
>> @@ -1663,6 +1685,7 @@ int dpm_suspend_late(pm_message_t state)
>>                 mutex_lock(&dpm_list_mtx);
>>
>>                 if (error || async_error) {
>> +                       dpm_async_suspend_complete_all(&dpm_late_early_list);
>>                         /*
>>                          * Move all devices to the target list to resume them
>>                          * properly.
>> @@ -1959,6 +1982,7 @@ int dpm_suspend(pm_message_t state)
>>                 mutex_lock(&dpm_list_mtx);
>>
>>                 if (error || async_error) {
>> +                       dpm_async_suspend_complete_all(&dpm_late_early_list);
> -> There is a bug here which is not present in the patch I've sent.

My bad, I edited by hand, sorry.

> 
> It should be
> 
>         dpm_async_suspend_complete_all(&dpm_prepared_list);


Wonderful, it seems this makes suspend happy on downstream pixel6!
I'm running some more tests and get back to you in a few hours.

> 
> It is also there in dpm_noirq_suspend_devices() above, but it probably
> doesn't matter.
> 
>>                         /*
>>                          * Move all devices to the target list to resume them
>>                          * properly.
>> @@ -1970,9 +1994,12 @@ int dpm_suspend(pm_message_t state)
>>
>>         mutex_unlock(&dpm_list_mtx);
>>
>> +       pr_err("tudor: %s: before async_synchronize_full\n", __func__);
>>         async_synchronize_full();
>>         if (!error)
>>                 error = async_error;
>> +       pr_err("tudor: %s: after async_synchronize_full();\n", __func__);
>> +
>>
>>         if (error)
>>                 dpm_save_failed_step(SUSPEND_SUSPEND);