linux-kernel - Re: [PATCH v5] cpuidle, ACPI: Evaluate LPI arch

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Message-ID: <20230913102721.GB12021@willie-the-truck>
Date:   Wed, 13 Sep 2023 11:27:21 +0100
From:   Will Deacon <will@...nel.org>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     Oza Pawandeep <quic_poza@...cinc.com>, catalin.marinas@....com,
        rafael@...nel.org, lenb@...nel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-acpi@...r.kernel.org
Subject: Re: [PATCH v5] cpuidle, ACPI: Evaluate LPI arch_flags for broadcast
 timer

On Wed, Sep 13, 2023 at 09:43:01AM +0100, Sudeep Holla wrote:
> On Tue, Sep 12, 2023 at 10:29:33AM -0700, Oza Pawandeep wrote:
> > Arm® Functional Fixed Hardware Specification defines LPI states,
> > which provide an architectural context loss flags field that can
> > be used to describe the context that might be lost when an LPI
> > state is entered.
> > 
> > - Core context Lost
> >         - General purpose registers.
> >         - Floating point and SIMD registers.
> >         - System registers, include the System register based
> >         - generic timer for the core.
> >         - Debug register in the core power domain.
> >         - PMU registers in the core power domain.
> >         - Trace register in the core power domain.
> > - Trace context loss
> > - GICR
> > - GICD
> > 
> > Qualcomm's custom CPUs preserves the architectural state,
> > including keeping the power domain for local timers active.
> > when core is power gated, the local timers are sufficient to
> > wake the core up without needing broadcast timer.
> > 
> > The patch fixes the evaluation of cpuidle arch_flags, and moves only to
> > broadcast timer if core context lost is defined in ACPI LPI.
> > 
> > Reviewed-by: Sudeep Holla <sudeep.holla@....com>
> 
> IIRC, Rafael had acked this, perhaps missing the tag ?
> Also just add a note to Will/Catalin that Rafael has acked and prefer to
> take it via arm64 tree.

Is this a fix? If so, please can I have a "Fixes:" tag (and does it need to
go into stable?)

Will