linux-kernel - Re: [PATCH v1 3/9] ACPI: processor: idle: Return failure when get lpi_state->arch

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Message-ID: <CAJZ5v0ivydYPk8yxEUdXJe=uATq_1=__J560v3VApcXAv=f_7Q@mail.gmail.com>
Date: Thu, 23 Oct 2025 12:09:39 +0200
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 3/9] ACPI: processor: idle: Return failure when get
 lpi_state->arch_flags failed

On Thu, Oct 23, 2025 at 11:59 AM lihuisong (C) <lihuisong@...wei.com> wrote:
>
>
> 在 2025/10/22 3:36, Rafael J. Wysocki 写道:
> > On Mon, Sep 29, 2025 at 11:38 AM Huisong Li <lihuisong@...wei.com> wrote:
> >> The architecture specific context loss flags is important for ARM.
> >> And this flag is used to control the execution of different code
> >> flows in acpi_processor_ffh_lpi_enter().
> >>
> >> So it is better to return failure when get lpi_state->arch_flags
> >> failed.
> > A failure means no idle states at all.
> Actually, I didn't know why driver should continue to do cpu idle
> scaling if the idle state doesn't meet the developer's expectations.🙂

There may be a firmware bug in one state description, but it doesn't
mean that the other states are unusable, does it?

> > Wouldn't it be better to skip the state with invalid arch flags?

> This arch flags is important.  And acpi_processor_ffh_lpi_enter will use it.
> There is no other place to verify its validity. so here do it.
> This check is just to prevent potential issues in cpuidle scaling later.

I'm saying to treat this particular state as invalid and skip it
without rejecting all of the other states that may be valid.