Message-ID: <028eba89-8176-740f-42df-736a0fcf26e7@mediatek.com>
Date:   Tue, 28 Jun 2022 09:53:31 +0800
From:   Peter Wang <peter.wang@...iatek.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
CC:     Matthias Brugger <matthias.bgg@...il.com>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Stanley Chu <stanley.chu@...iatek.com>,
        "Linux ARM" <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Avri Altman <avri.altman@....com>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        wsd_upstream <wsd_upstream@...iatek.com>,
        "moderated list:ARM/Mediatek SoC..." 
        <linux-mediatek@...ts.infradead.org>, <chun-hung.wu@...iatek.com>,
        <alice.chao@...iatek.com>, <cc.chou@...iatek.com>,
        <chaotian.jing@...iatek.com>, <jiajie.hao@...iatek.com>,
        <powen.kao@...iatek.com>, <qilin.tan@...iatek.com>,
        <lin.gui@...iatek.com>, <tun-yu.yu@...iatek.com>
Subject: Re: [PATCH v1] PM-runtime: Check supplier_preactivated before release
 supplier


On 6/28/22 3:00 AM, Rafael J. Wysocki wrote:
> On Mon, Jun 13, 2022 at 2:08 PM <peter.wang@...iatek.com> wrote:
>> From: Peter Wang <peter.wang@...iatek.com>
>>
>> With divice link of DL_FLAG_PM_RUNTIME, if consumer call pm_runtime_get_suppliers
>> to prevent supplier enter suspend, pm_runtime_release_supplier should
>> check supplier_preactivated before let supplier enter suspend.
> Why?

because supplier_preactivated is true means supplier cannot enter 
suspend, right?


>> If the link is drop or release, bypass check supplier_preactivated.
>>
>> Signed-off-by: Peter Wang <peter.wang@...iatek.com>
>> ---
>>   drivers/base/core.c          |  2 +-
>>   drivers/base/power/runtime.c | 15 ++++++++++++---
>>   include/linux/pm_runtime.h   |  5 +++--
>>   3 files changed, 16 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/base/core.c b/drivers/base/core.c
>> index 7cd789c4985d..3b9cc559928f 100644
>> --- a/drivers/base/core.c
>> +++ b/drivers/base/core.c
>> @@ -486,7 +486,7 @@ static void device_link_release_fn(struct work_struct *work)
>>          /* Ensure that all references to the link object have been dropped. */
>>          device_link_synchronize_removal();
>>
>> -       pm_runtime_release_supplier(link, true);
>> +       pm_runtime_release_supplier(link, true, true);
>>
>>          put_device(link->consumer);
>>          put_device(link->supplier);
>> diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
>> index 676dc72d912d..3c4f425937a1 100644
>> --- a/drivers/base/power/runtime.c
>> +++ b/drivers/base/power/runtime.c
>> @@ -314,10 +314,19 @@ static int rpm_get_suppliers(struct device *dev)
>>    * and if @check_idle is set, check if that device is idle (and so it can be
>>    * suspended).
>>    */
>> -void pm_runtime_release_supplier(struct device_link *link, bool check_idle)
>> +void pm_runtime_release_supplier(struct device_link *link, bool check_idle,
>> +       bool drop)
>>   {
>>          struct device *supplier = link->supplier;
>>
>> +       /*
>> +        * When consumer hold supplier, supplier cannot enter suspend.
>> +        * Driect release supplier and let supplier enter suspend is not allow.
>> +        * Unless the link is drop, direct relsease supplier should be okay.
>> +        */
>> +       if (link->supplier_preactivated && !drop)
>> +               return;
>> +
>>          /*
>>           * The additional power.usage_count check is a safety net in case
>>           * the rpm_active refcount becomes saturated, in which case
>> @@ -338,7 +347,7 @@ static void __rpm_put_suppliers(struct device *dev, bool try_to_suspend)
>>
>>          list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
>>                                  device_links_read_lock_held())
>> -               pm_runtime_release_supplier(link, try_to_suspend);
>> +               pm_runtime_release_supplier(link, try_to_suspend, false);
>>   }
>>
>>   static void rpm_put_suppliers(struct device *dev)
>> @@ -1838,7 +1847,7 @@ void pm_runtime_drop_link(struct device_link *link)
>>                  return;
>>
>>          pm_runtime_drop_link_count(link->consumer);
>> -       pm_runtime_release_supplier(link, true);
>> +       pm_runtime_release_supplier(link, true, true);
>>   }
>>
>>   static bool pm_runtime_need_not_resume(struct device *dev)
>> diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
>> index 9e4d056967c6..354ffb1eaec0 100644
>> --- a/include/linux/pm_runtime.h
>> +++ b/include/linux/pm_runtime.h
>> @@ -88,7 +88,8 @@ extern void pm_runtime_get_suppliers(struct device *dev);
>>   extern void pm_runtime_put_suppliers(struct device *dev);
>>   extern void pm_runtime_new_link(struct device *dev);
>>   extern void pm_runtime_drop_link(struct device_link *link);
>> -extern void pm_runtime_release_supplier(struct device_link *link, bool check_idle);
>> +extern void pm_runtime_release_supplier(struct device_link *link,
>> +       bool check_idle, bool drop);
>>
>>   extern int devm_pm_runtime_enable(struct device *dev);
>>
>> @@ -315,7 +316,7 @@ static inline void pm_runtime_put_suppliers(struct device *dev) {}
>>   static inline void pm_runtime_new_link(struct device *dev) {}
>>   static inline void pm_runtime_drop_link(struct device_link *link) {}
>>   static inline void pm_runtime_release_supplier(struct device_link *link,
>> -                                              bool check_idle) {}
>> +                                              bool check_idle, bool drop) {}
>>
>>   #endif /* !CONFIG_PM */
>>
>> --
>> 2.18.0
>>

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