linux-kernel - Re: [PATCH V3 0/6] cpufreq: suspend early/resume late

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Message-ID: <5293C327.2030606@ti.com>
Date:	Mon, 25 Nov 2013 15:37:43 -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>, <swarren@...dotorg.org>,
	<kgene.kim@...sung.com>, <linux-samsung-soc@...r.kernel.org>,
	<linux-tegra@...r.kernel.org>, <jinchoi@...adcom.com>,
	<tianyu.lan@...el.com>, <sebastian.capella@...aro.org>,
	<jhbird.choi@...sung.com>
Subject: Re: [PATCH V3 0/6] cpufreq: suspend early/resume late

On 11/25/2013 08:11 AM, Viresh Kumar wrote:
> This patchset adds cpufreq callbacks to dpm_{suspend|resume}() for handling
> suspend/resume of cpufreq governors and core. This is required for early suspend
> and late resume of governors and cpufreq core.
> 
> 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. Many platforms have such problems, samsung, tegra,
>   etc.. They solved it with driver specific PM notifiers where they used to
>   disable their driver's ->target() routine. Most of these are updated in this
>   patchset to use new infrastructure.
> 
> - 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. This is also fixed with this patch as don't
>   allow any operation on Governors during suspend/resume now.
> 
> 
> So to solve these issues we introduce early suspend and late resume callbacks
> which would remove need of cpufreq drivers to implement PM notifiers to disable
> transition after suspend and before resume.
> 
> @Nishanth: Can you please test V2 as well and confirm that suspend_noirq()
> doesn't work for you. I am sure it will not, but would be better if you confirm
> that.
> 
> Viresh Kumar (6):
>   cpufreq: suspend governors on system suspend/hibernate
>   cpufreq: call driver's suspend/resume for each policy
patches 1-2,
Tested-by: Nishanth Menon <nm@...com>
http://pastebin.mozilla.org/3670932

Prior to these two patches: http://pastebin.mozilla.org/3670933
cpufreq driver used: cpufreq_cpu0


-- 
Regards,
Nishanth Menon
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