linux-kernel - Re: [PATCH 8/8] intel_idle: create a native cpuidle driver for select intel processors

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Date:	Thu, 27 May 2010 23:57:42 -0400 (EDT)
From:	Len Brown <lenb@...nel.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	x86@...nel.org, linux-pm@...ts.linux-foundation.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 8/8] intel_idle: create a native cpuidle driver for select
 intel processors


> ... What happens when an additional CPU is brought online? 
> It melts?  ;)

With the current driver, processors hot-added after modprobe
will use C1 only, and not use deeper C-states.

Taking online processors offline and bringing them back online
(like we do during suspend) works fine.

> > +		dev->cpu = i;
> > +		if (cpuidle_register_device(dev)) {
> > +			pr_debug(PREFIX "cpuidle_register_device %d failed!\n", i);
> > +			free_percpu(intel_idle_cpuidle_devices);
> > +			return -EIO;
> 
> Should this unregister all the thus-far-registered devices?

yes, that was a bug!

thanks,
Len Brown, Intel Open Source Technology Center

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