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

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Message-ID: <20250402-messy-wild-squid-7b4da9@sudeepholla>
Date: Wed, 2 Apr 2025 12:56:53 +0100
From: Sudeep Holla <sudeep.holla@....com>
To: Youngmin Nam <youngmin.nam@...sung.com>
Cc: Marc Zyngier <maz@...nel.org>, Thomas Gleixner <tglx@...utronix.de>,
	Saravana Kannan <saravanak@...gle.com>,
	Sudeep Holla <sudeep.holla@....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,
	d7271.choe@...sung.com, joonki.min@...sung.com
Subject: Re: [GICv3 ITS]S2IDLE framework does not invoke syscore_ops in GICv3
 ITS driver

(Failed to find the original email, so reply on this instead)

On Thu, Mar 27, 2025 at 12:22:19PM +0900, Youngmin Nam wrote:
> 
> The problem is that syscore_ops is not invoked during the S2IDLE scenario,
> so we cannot rely on it in that context.
> We would like to use these suspend/resume functions during S2IDLE as well.

I have one orthogonal question. The s2idle will just use the deepest
cpuidle state registered. So if s2idle needs this save/restore of GICv3
ITS, how does that work when all the CPUs enter that idle state.

With respect to the PSCI CPU_SUSPEND call, it doesn't change. So I am
bit confused as how it can work fine in normal cpuidle paths but no in
s2idle path. What am I missing ? I do psci_enter_domain_idle_state handles
s2idle little different but nothing to change this GICv3 ITS save/restore
requirement between cpuidle and s2idle.

-- 
Regards,
Sudeep