linux-kernel - Re: [PATCH 1/3] cpuidle: Add enable

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Message-ID: <2d2d2d40-c73a-4988-90fe-fad75e35c75b@huawei.com>
Date: Fri, 30 Jan 2026 09:59:40 +0800
From: "lihuisong (C)" <lihuisong@...wei.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
CC: <lenb@...nel.org>, <linux-acpi@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <Sudeep.Holla@....com>,
	<linuxarm@...wei.com>, <jonathan.cameron@...wei.com>,
	<zhanjie9@...ilicon.com>, <zhenglifeng1@...wei.com>, <yubowen8@...wei.com>
Subject: Re: [PATCH 1/3] cpuidle: Add enable_cpuidle() interface

Hi Rafael,

On 1/15/2026 8:18 PM, lihuisong (C) wrote:
>
> On 1/15/2026 3:18 AM, Rafael J. Wysocki wrote:
>> On Tue, Nov 25, 2025 at 8:29 AM Huisong Li <lihuisong@...wei.com> wrote:
>>> The global switch of cpuidle can be turned back on in some case.
>>> So add enable_cpuidle().
>> No, this is not going to work.  The "off" switch only affects
>> initialization AFAICS.
> I think it would be work.
> The cpuidle_not_available() also see the "off" on do_idle().
> And cpuidle_idle_call() check this function first and then select idle 
> state.
> Cpuidle doesn't select and enter idle state if this fuction return true.
I verified that disable_cpuidle() effectively prevents all CPUs from 
entering any idle states and the cpuidle function is correctly restored 
after calling enable_cpuidle().
What do you think?

Best,
/Huisong
>>> Signed-off-by: Huisong Li <lihuisong@...wei.com>
>>> ---
>>>   drivers/cpuidle/cpuidle.c | 5 ++++-
>>>   include/linux/cpuidle.h   | 2 ++
>>>   2 files changed, 6 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
>>> index 56132e843c99..980ddfd3d930 100644
>>> --- a/drivers/cpuidle/cpuidle.c
>>> +++ b/drivers/cpuidle/cpuidle.c
>>> @@ -48,7 +48,10 @@ void disable_cpuidle(void)
>>>   {
>>>          off = 1;
>>>   }
>>> -
>>> +void enable_cpuidle(void)
>>> +{
>>> +       off = 0;
>>> +}
>>>   bool cpuidle_not_available(struct cpuidle_driver *drv,
>>>                             struct cpuidle_device *dev)
>>>   {
>>> diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
>>> index a9ee4fe55dcf..94c030748af3 100644
>>> --- a/include/linux/cpuidle.h
>>> +++ b/include/linux/cpuidle.h
>>> @@ -168,6 +168,7 @@ struct cpuidle_driver {
>>>   };
>>>
>>>   #ifdef CONFIG_CPU_IDLE
>>> +extern void enable_cpuidle(void);
>>>   extern void disable_cpuidle(void);
>>>   extern bool cpuidle_not_available(struct cpuidle_driver *drv,
>>>                                    struct cpuidle_device *dev);
>>> @@ -203,6 +204,7 @@ extern struct cpuidle_driver 
>>> *cpuidle_get_cpu_driver(struct cpuidle_device *dev)
>>>   static inline struct cpuidle_device *cpuidle_get_device(void)
>>>   {return __this_cpu_read(cpuidle_devices); }
>>>   #else
>>> +static inline void enable_cpuidle(void) { }
>>>   static inline void disable_cpuidle(void) { }
>>>   static inline bool cpuidle_not_available(struct cpuidle_driver *drv,
>>>                                           struct cpuidle_device *dev)
>>> -- 
>>> 2.33.0
>>>