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

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Date:   Wed, 13 Sep 2023 09:43:01 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Oza Pawandeep <quic_poza@...cinc.com>
Cc:     catalin.marinas@....com, will@...nel.org, rafael@...nel.org,
        Sudeep Holla <sudeep.holla@....com>, 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 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.

-- 
Regards,
Sudeep