linux-kernel - Re: [PATCH V2 1/2] cpufreq: suspend governors on system suspend/hibernate

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Date:	Mon, 25 Nov 2013 15:30:21 -0600
From:	Nishanth Menon <nm@...com>
To:	Viresh Kumar <viresh.kumar@...aro.org>, <rjw@...ysocki.net>
CC:	<linaro-kernel@...ts.linaro.org>, <patches@...aro.org>,
	<cpufreq@...r.kernel.org>, <linux-pm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <tianyu.lan@...el.com>,
	<jinchoi@...adcom.com>, <sebastian.capella@...aro.org>
Subject: Re: [PATCH V2 1/2] cpufreq: suspend governors on system suspend/hibernate

On 11/22/2013 05:29 AM, Viresh Kumar wrote:
> This patch adds cpufreq callbacks to dpm_{suspend|resume}_noirq() for handling
> suspend/resume of cpufreq governors. This is required for early suspend and late
> resume of governors.
> 
> There are multiple problems that are fixed by this patch:
> - Nishanth Menon (TI) found an interesting problem on his platform, OMAP. His board
>   wasn't working well with suspend/resume as calls for removing non-boot CPUs
>   was turning out into a call to drivers ->target() which then tries to play
>   with regulators. But regulators and their I2C bus were already suspended and
>   this resulted in a failure. This is why we need a PM notifier here.
> - Lan Tianyu (Intel) & Jinhyuk Choi (Broadcom) found another issue where
>   tunables configuration for clusters/sockets with non-boot CPUs was getting
>   lost after suspend/resume, as we were notifying governors with
>   CPUFREQ_GOV_POLICY_EXIT on removal of the last cpu for that policy and so
>   deallocating memory for tunables.
> 
> Reported-by: Lan Tianyu <tianyu.lan@...el.com>
> Reported-by: Nishanth Menon <nm@...com>
> Reported-by: Jinhyuk Choi <jinchoi@...adcom.com>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
>  drivers/base/power/main.c |  3 +++
>  drivers/cpufreq/cpufreq.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/cpufreq.h   |  3 +++
>  3 files changed, 68 insertions(+)
yes, this seems to work for me as well.
http://pastebin.mozilla.org/3670909 - no cpufreq attempts to
transition were triggered.

-- 
Regards,
Nishanth Menon
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