linux-kernel - Re: [PATCH v1 2/9] ACPI: processor: idle: Return failure if entry method is not buffer or integer type

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Message-ID: <CAJZ5v0jyOM-DMAGi5MxdDxjZsgFWeSL_dqiZx3imAPShMyeoNQ@mail.gmail.com>
Date: Sun, 26 Oct 2025 13:35:46 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: "lihuisong (C)" <lihuisong@...wei.com>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, 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 2/9] ACPI: processor: idle: Return failure if entry
 method is not buffer or integer type

On Fri, Oct 24, 2025 at 11:25 AM lihuisong (C) <lihuisong@...wei.com> wrote:
>
>
> 在 2025/10/23 18:07, Rafael J. Wysocki 写道:
> > On Thu, Oct 23, 2025 at 11:25 AM lihuisong (C) <lihuisong@...wei.com> wrote:
> >>
> >> 在 2025/10/22 3:34, Rafael J. Wysocki 写道:
> >>> On Mon, Sep 29, 2025 at 11:38 AM Huisong Li <lihuisong@...wei.com> wrote:
> >>>> According to ACPI spec, entry method in LPI sub-package must be buffer
> >>>> or integer. However, acpi_processor_evaluate_lpi() regeards it as success
> >>>> and treat it as an effective LPI state.
> >>> Is that the case?  AFAICS, it just gets to the next state in this case
> >>> and what's wrong with that?
> >> The flatten_lpi_states() would consider the state with illegal entry
> >> method sub-package as a valid one
> >> if the flag of this state is enabled(ACPI_LPI_STATE_FLAGS_ENABLED is set).
> >> And then cpuidle governor would use it because the caller of
> >> acpi_processor_ffh_lpi_probe() also don't see the return value.
> > So the problem appears to be that lpi_state increments in every step
> > of the loop, but it should only increment if the given state is valid.
> Yes,
> So set the flag of the state with illegal entry method sub-package to
> zero so that this invalid LPI state will be skiped in
> flatten_lpi_states(), ok?

Sounds reasonable.