linux-kernel - Re: [PATCH 4/6] ARM: psci: cpuidle: Introduce PSCI CPUidle driver

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Date:   Wed, 7 Aug 2019 18:30:28 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        linux-pm@...r.kernel.org
Cc:     Ulf Hansson <ulf.hansson@...aro.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Mark Rutland <mark.rutland@....com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        LAKML <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 4/6] ARM: psci: cpuidle: Introduce PSCI CPUidle driver

On 22/07/2019 17:37, Lorenzo Pieralisi wrote:
> PSCI firmware is the standard power management control for
> all ARM64 based platforms and it is also deployed on some
> ARM 32 bit platforms to date.
> 
> Idle state entry in PSCI is currently achieved by calling
> arm_cpuidle_init() and arm_cpuidle_suspend() in a generic
> idle driver, which in turn relies on ARM/ARM64 CPUidle back-end
> to relay the call into PSCI firmware if PSCI is the boot method.
> 
> Given that PSCI is the standard idle entry method on ARM64 systems
> (which means that no other CPUidle driver are expected on ARM64
> platforms - so PSCI is already a generic idle driver), in order to
> simplify idle entry and code maintenance, it makes sense to have a PSCI
> specific idle driver so that idle code that it is currently living in
> drivers/firmware directory can be hoisted out of it and moved
> where it belongs, into a full-fledged PSCI driver, leaving PSCI code
> in drivers/firmware as a pure firmware interface, as it should be.
> 
> Implement a PSCI CPUidle driver. By default it is a silent Kconfig entry
> which is left unselected, since it selection would clash with the
> generic ARM CPUidle driver that provides a PSCI based idle driver
> through the arm/arm64 arches back-ends CPU operations.
> 
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> Cc: Ulf Hansson <ulf.hansson@...aro.org>
> Cc: Sudeep Holla <sudeep.holla@....com>
> Cc: Daniel Lezcano <daniel.lezcano@...aro.org>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
> ---

Modulo Ulf and Sudeep comments,

Acked-by: Daniel Lezcano <daniel.lezcano@...aro.org>


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