linux-kernel - Re: [PATCH v2 1/7] ACPI: processor: idle: Mark the state as invalid if its entry method is illegal

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Message-ID: <0140a714-a092-4bb8-af93-e3723fba20f1@huawei.com>
Date: Wed, 5 Nov 2025 16:53:30 +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 v2 1/7] ACPI: processor: idle: Mark the state as invalid
 if its entry method is illegal


在 2025/11/4 23:00, Rafael J. Wysocki 写道:
> On Tue, Nov 4, 2025 at 10:30 AM lihuisong (C) <lihuisong@...wei.com> wrote:
>>
>> 在 2025/11/4 1:49, Rafael J. Wysocki 写道:
>>> On Mon, Nov 3, 2025 at 9:42 AM Huisong Li <lihuisong@...wei.com> wrote:
>>>> According to ACPI spec, entry method in LPI sub-package must be buffer
>>>> or integer. And the entry method is very key in cpuidle. So mark the state
>>>> as invalid.
>>>>
>>>> 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 | 3 +++
>>>>    1 file changed, 3 insertions(+)
>>>>
>>>> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
>>>> index 341825e8ac63..9f1040eac051 100644
>>>> --- a/drivers/acpi/processor_idle.c
>>>> +++ b/drivers/acpi/processor_idle.c
>>>> @@ -956,6 +956,9 @@ static int acpi_processor_evaluate_lpi(acpi_handle handle,
>>>>                           lpi_state->entry_method = ACPI_CSTATE_INTEGER;
>>>>                           lpi_state->address = obj->integer.value;
>>>>                   } else {
>>>> +                       pr_debug("Entry method of state-%d is illegal, disable it.\n",
>>>> +                                state_idx);
>>>> +                       lpi_state->flags = 0;
>>> Why does lpi_state->flags need to be cleared, isn't it 0 already?
>> Good point.
>> Do we need to add debug log?
> Well, is it helpful?
I think it is useful for developers.
They have a way to know why a state is disabled.
>