linux-kernel - Re: [PATCH v2 1/2] cpufreq: Add exit_prepare callback to cpufreq

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Date:	Tue, 18 Mar 2014 11:13:08 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Dirk Brandewie <dirk.brandewie@...il.com>,
	Linux PM list <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Patrick Marlier <patrick.marlier@...il.com>,
	Dirk Brandewie <dirk.j.brandewie@...el.com>
Subject: Re: [PATCH v2 1/2] cpufreq: Add exit_prepare callback to
 cpufreq_driver interface

On Sat, Mar 15, 2014 at 7:34 AM, Rafael J. Wysocki <rjw@...ysocki.net> wrote:
> On Friday, March 14, 2014 02:03:56 PM dirk.brandewie@...il.com wrote:

>> +++ b/drivers/cpufreq/cpufreq.c
>> @@ -1338,6 +1338,9 @@ static int __cpufreq_remove_dev_prepare(struct device *dev,
>>               }
>>       }
>>
>> +     if (cpufreq_driver->stop)
>
> What about doing
>
> +       if (cpufreq_driver->setpolicy && cpufreq_driver->stop)
>
> here instead?  That would make it clear where the new callback belongs.

This is called after stopping governor and so might be useful for ->target()
drivers. So, wouldn't be a bad option if we keep it available for all..

@Dirk: I thought about the solution I mentioned in another mail. And it looks
like I will end up getting a similar solution. So, we will go with
your solution.

Just few changes for your solution..

You need to call ->stop() only for the last CPU of every policy and not for
every CPU, so you need something like this:

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 19d25a8..78d41c0 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1371,6 +1371,8 @@ static int __cpufreq_remove_dev_prepare(struct
device *dev,
                                         __func__, new_cpu, cpu);
                        }
                }
+       } else if (cpufreq_driver->stop) {
+               cpufreq_driver->stop(policy);
        }

        return 0;
--
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