linux-kernel - Re: [PATCH V4] PM / OPP: Pass opp_table to dev_pm_opp_put

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Message-id: <583F80AB.5040408@samsung.com>
Date:   Thu, 01 Dec 2016 10:45:15 +0900
From:   Joonyoung Shim <jy0922.shim@...sung.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Rafael Wysocki <rjw@...ysocki.net>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        "# v4 . 4+" <stable@...r.kernel.org>,
        Joonyoung Shim <jy0922.shim@...sung.com>
Subject: Re: [PATCH V4] PM / OPP: Pass opp_table to dev_pm_opp_put_regulator()

On 11/30/2016 05:05 PM, Viresh Kumar wrote:
> On 30-11-16, 15:19, Joonyoung Shim wrote:
>> Hi Viresh,
>>
>> On 11/30/2016 12:59 PM, Viresh Kumar wrote:
>>> From: Stephen Boyd <sboyd@...eaurora.org>
>>>
>>> Joonyoung Shim reported an interesting problem on his ARM octa-core
>>> Odoroid-XU3 platform. During system suspend, dev_pm_opp_put_regulator()
>>> was failing for a struct device for which dev_pm_opp_set_regulator() is
>>> called earlier.
>>>
>>> This happened because an earlier call to
>>> dev_pm_opp_of_cpumask_remove_table() function (from cpufreq-dt.c file)
>>> removed all the entries from opp_table->dev_list apart from the last CPU
>>> device in the cpumask of CPUs sharing the OPP.
>>>
>>> But both dev_pm_opp_set_regulator() and dev_pm_opp_put_regulator()
>>> routines get CPU device for the first CPU in the cpumask. And so the OPP
>>> core failed to find the OPP table for the struct device.
>>>
>>> In order to fix that up properly, we need to revisit APIs like
>>> dev_pm_opp_set_regulator() and make them talk in terms of cookies
>>> provided by the OPP core. But such a solution will be hard to backport
>>> to stable kernels.
>>>
>>> This patch attempts to fix this problem by returning a pointer to the
>>> opp_table from dev_pm_opp_set_regulator() and using that as the
>>> parameter to dev_pm_opp_put_regulator(). This ensures that the
>>> dev_pm_opp_put_regulator() doesn't fail to find the opp table.
>>>
>>> Note that similar design problem also exists with other
>>> dev_pm_opp_put_*() APIs, but those aren't used currently by anyone and
>>> so we don't need to update them for now.
>>>
>>> [Viresh]: Written commit log, minor improvements in the patch and tested
>>> on exynos 5250.
>>>
>>> Cc: # v4.4+ <stable@...r.kernel.org>
>>> Reported-by: Joonyoung Shim <jy0922.shim@...sung.com>
>>> Signed-off-by: Stephen Boyd <sboyd@...eaurora.org>
>>> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
>>> ---
>>> V3->V4:
>>> - Completely different approach, suggested earlier by Stephen.
>>> - Can be merged safely now as both /me and Stephen agree to this one.
>>>
>>> @Joonyoung: Can you please test this last patch please ?
>>>
>>
>> Just system suspend/resume is working
> 
> Should I consider that as a Tested-by from you for the problem you
> reported at least ?
> 

My Tested-by is ok about the original problem reported by me.

>> but i was missing below test case
>> that you inform when i test for prior patches on my Odroid-XU3 board.
>>
>> - offline CPU 4
>> - suspend the system
>>
>> With this test case, now all patches posted have the problem that is
>> failed to get clk: -2.
> 
> That probably happens because your DT isn't good enough. Following DT
> change may fix it for you:
> 

Already i tried and the error was gone but sometimes system resume is
halt. I'm not sure that it has any effect so i need to more dig.

Thanks.