Re: s2idle breaks on machines without cpuidle support

From: Sudeep Holla <sudeep.holla@arm.com>
To: Kazuki <kazukih0205@gmail.com>
Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Sudeep Holla <sudeep.holla@arm.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Lorenzo Pieralisi <lpieralisi@kernel.org>,
	Hector Martin <marcan@marcan.st>, Sven Peter <sven@svenpeter.dev>,
	Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>
Subject: Re: s2idle breaks on machines without cpuidle support
Date: Wed, 8 Feb 2023 15:34:07 +0000	[thread overview]
Message-ID: <20230208153407.4a5vnbctf77xf5vf@bogus> (raw)
In-Reply-To: <20230208151939.meya6c5gayspvmtr@kazuki-mac>

On Thu, Feb 09, 2023 at 12:19:39AM +0900, Kazuki wrote:
> On Wed, Feb 08, 2023 at 03:03:06PM +0000, Sudeep Holla wrote:

[...]

> > Well, if we are allowing to boot on such a system, then we must allow
> > adding a platform specific idle driver. It may be useful once we info
> > to add deeper than WFI states.
>
> Hmmm, I thought for arm64, non-PSCI idle drivers were prohibited? Or am
> I mistaken here?

I don't know. I am not against it especially now that we have allowed a
non-PSCI based production system to boot the kernel.

> > Are we ? I thought were making changes to enable it. Or are you saying
> > we allow to enter into such a state and render the system unusable, if
> > so we need to fix it.
>
> Both as I mentioned in my first email. Apologies if it turned out to
> be confusing.

Sorry still confusing. Are you saying you can enter s2idle and crash or
hang the system without changes(especially around this s2idle code) ?

If yes, then it is a bug. If the hang/crash is only after your changes,
we need to check.

-- 
Regards,
Sudeep