linux-kernel - Re: [PATCH v1 5/9] ACPI: processor: idle: Add the verification of processor FFH LPI state

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Message-ID: <92b1b431-9855-43fb-8bb3-801649064438@huawei.com>
Date: Thu, 23 Oct 2025 18:17:01 +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 v1 5/9] ACPI: processor: idle: Add the verification of
 processor FFH LPI state


在 2025/10/22 3:42, Rafael J. Wysocki 写道:
> On Mon, Sep 29, 2025 at 11:38 AM Huisong Li <lihuisong@...wei.com> wrote:
>> Both ARM64 and RISCV architecture would validate Entry Method of LPI
>> state and SBI HSM or PSCI cpu suspend. Driver should return failure
>> if FFH of LPI state are not ok.
> First of all, I cannot parse this changelog, so I don't know the
> motivation for the change.
Sorry for your confusion.
> Second, if _LPI is ever used on x86, the
> acpi_processor_ffh_lpi_probe() in acpi_processor_get_power_info() will
> get in the way.
AFAICS, it's also ok if X86 platform use LPI.
>
> Why does the evaluation in acpi_processor_setup_cpuidle_dev() not work?
The acpi_processor_ffh_lpi_probe does verify the validity of LPI for ARM 
and RISCV.
But the caller of the acpi_processor_setup_cpuidle_dev()don't verify the 
return value.
In addition, from the name of acpi_processor_setup_cpuidle_dev(), its 
main purpose is to setup cpudile device rather than to verify LPI.
So I move it to a more prominent position and redefine the 
acpi_processor_setup_cpuidle_dev to void in patch 9/9.
>
>> Fixes: a36a7fecfe60 ("ACPI / processor_idle: Add support for Low Power Idle(LPI) states")
>> Signed-off-by: Huisong Li <lihuisong@...wei.com>
>> ---
>>   drivers/acpi/processor_idle.c | 10 ++++++++--
>>   1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
>> index 5684925338b3..b0d6b51ee363 100644
>> --- a/drivers/acpi/processor_idle.c
>> +++ b/drivers/acpi/processor_idle.c
>> @@ -1264,7 +1264,7 @@ static int acpi_processor_setup_cpuidle_dev(struct acpi_processor *pr,
>>
>>          dev->cpu = pr->id;
>>          if (pr->flags.has_lpi)
>> -               return acpi_processor_ffh_lpi_probe(pr->id);
>> +               return 0;
>>
>>          return acpi_processor_setup_cpuidle_cx(pr, dev);
>>   }
>> @@ -1275,7 +1275,13 @@ static int acpi_processor_get_power_info(struct acpi_processor *pr)
>>
>>          ret = acpi_processor_get_lpi_info(pr);
>>          if (ret)
>> -               ret = acpi_processor_get_cstate_info(pr);
>> +               return acpi_processor_get_cstate_info(pr);
>> +
>> +       if (pr->flags.has_lpi) {
>> +               ret = acpi_processor_ffh_lpi_probe(pr->id);
>> +               if (ret)
>> +                       pr_err("Processor FFH LPI state is invalid.\n");
>> +       }
>>
>>          return ret;
>>   }
>> --
>> 2.33.0
>>