linux-kernel - [PATCH 0/2] cpuidle: Avoid returning a disabled C-state from menu governor

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Message-ID: <2471963.urOyfY8mOG@vostro.rjw.lan>
Date:	Sun, 27 Apr 2014 14:53:09 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Linux PM list <linux-pm@...r.kernel.org>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	'Daniel Lezcano' <daniel.lezcano@...aro.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: [PATCH 0/2] cpuidle: Avoid returning a disabled C-state from menu governor

Hi,

The cpuidle menu governor has a problem that it returns 0 when it can't find
a suitable C-state, but on some systems in some situations 0 may be the
CPUIDLE_DRIVER_STATE_START index and it shouldn't be returned if the corresponding
C-state has been disabled, for example.

The following two patches avoid this issue by modifying the menu governor to
return an error code rather than 0 in those situations.

[1/2] Combine cpuidle_enabled() with cpuidle_select(), because [2/2] makes
      the latter return negative error codes sometimes, so keeping them separate
      is not useful any more.

[2/2] Modify the menu governor to return an error code if the extra "poll" state
      is not available.

Thanks!


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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