linux-kernel - Re: [stable -3.14] PM backports for pm_test / CONFIG_PM

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Message-ID: <1849024.CHOUso6H2K@vostro.rjw.lan>
Date:	Thu, 04 Sep 2014 21:40:41 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Brian Norris <computersforpeace@...il.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	linux-pm@...r.kernel.org, Len Brown <len.brown@...el.com>,
	Pavel Machek <pavel@....cz>, Zhang Rui <rui.zhang@...el.com>
Subject: Re: [stable -3.14] PM backports for pm_test / CONFIG_PM_DEBUG

On Wednesday, September 03, 2014 06:02:19 PM Brian Norris wrote:
> Hi,
> 
> If I enable CONFIG_PM_DEBUG on a 3.14.y kernel, I can see the following
> results:
> 
>     # cat /sys/power/state
>     freeze standby mem
>     # cat /sys/power/pm_test
>     [none] core processors platform devices freezer
>     # echo core > /sys/power/pm_test
>     # cat /sys/power/state
>     [   22.581289] Unsupported pm_test mode for freeze state, please choose none/freezer/devices/platform.
>     standby mem
> 
> Note how 'freeze' is dropped from the supported states, and I get an
> extra printk message when I'm just checking if the state is valid.
> 
> It looks like if I backport a few fixes, I get more sane behavior, where
> the warnings (and -EAGAIN) appear only when I actually try to enter an
> unsupported test mode:
> 
>     # echo core > /sys/power/pm_test
>     # cat /sys/power/state
>     freeze standby mem
>     # echo freeze > /sys/power/state
>     [   27.833141] PM: Unsupported test mode for freeze state,please choose none/freezer/devices/platform.
>     sh: echo: write error: Resource temporarily unavailable
> 
> I think I've narrowed it down to this commit that should be backported
> to -stable (for 3.9+?):
> 
>     43e8317b0bba PM / sleep: Use valid_state() for platform-dependent sleep states only
> 
> But it needs to drag along this dependency too:
> 
>     27ddcc6596e5 PM / sleep: Add state field to pm_states[] entries

That sounds OK.

Can you please send a formal request to include the two commits above to Greg/stable?

> While at this, it looks like this commit might be deserving of -stable
> (3.9+). I haven't tested this one, as I don't have a good freeze+cpuidle
> setup; it just shows up in the commit log with an interesting
> description and a 'Fixes' tag:
> 
>     f3f125324fc1 PM / suspend: Make cpuidle work in the "freeze" state

Well, it basically makes the freeze state save energy, but it's not essential.

I'm not seeing the "Fixes:" tag on it, though.

Rafael

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