linux-kernel - Re: [GICv3 ITS]S2IDLE framework does not invoke syscore

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Message-ID: <20250407-amiable-perfect-hummingbird-06ad83@sudeepholla>
Date: Mon, 7 Apr 2025 10:17:43 +0100
From: Sudeep Holla <sudeep.holla@....com>
To: Donghyeok Choe <d7271.choe@...sung.com>
Cc: Youngmin Nam <youngmin.nam@...sung.com>, Marc Zyngier <maz@...nel.org>,
	Sudeep Holla <sudeep.holla@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Saravana Kannan <saravanak@...gle.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	kernel-team@...roid.com, hajun.sung@...sung.com,
	joonki.min@...sung.com, ne.yoo@...sung.com
Subject: Re: [GICv3 ITS]S2IDLE framework does not invoke syscore_ops in GICv3
 ITS driver

On Fri, Apr 04, 2025 at 01:13:23PM +0900, Donghyeok Choe wrote:
> On Thu, Apr 03, 2025 at 10:18:54AM +0100, Sudeep Holla wrote:
> > /me more confused.
> > 
> > Are you saying you have some cpuidle platform specific logic inside
> > trace_android_vh_cpuidle_psci_enter(). I would assume it was just to
> > trace the entry into the state and nothing more.
> 
> If you have any further questions, feel free to reach out.
> 

I was trying to understand the difference in behaviour between normal
cpuidle entering the same deepest state that is entered in s2idle state.
I assume GIC doesn't loose power and no need for GIC ITS save/restore
in normal cpuidle path ?

If so, what triggers the GIC suspend in s2idle path if syscore_ops is
not getting called ?

Why would the firmware pull the plug on GIC ?

Do you use any suspend/resume logic in drivers/irqchip/irq-gic-pm.c ?
I am still missing something in this flow.

-- 
Regards,
Sudeep