linux-kernel - Re: [PATCH v2 20/20] cpufreq: Return zero on success in boost sw setting

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Date:   Tue, 19 May 2020 09:50:03 +0800
From:   Xiongfeng Wang <wangxiongfeng2@...wei.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Serge Semin <Sergey.Semin@...kalelectronics.ru>
CC:     Serge Semin <fancer.lancer@...il.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        "Matthias Kaehlcke" <mka@...omium.org>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Paul Burton <paulburton@...nel.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Arnd Bergmann <arnd@...db.de>,
        "Rob Herring" <robh+dt@...nel.org>, <linux-mips@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Stable <stable@...r.kernel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        "Ingo Molnar" <mingo@...nel.org>, Yue Hu <huyue2@...ong.com>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 20/20] cpufreq: Return zero on success in boost sw
 setting

Hi Rafael,

On 2020/5/18 19:05, Rafael J. Wysocki wrote:
> On Mon, May 18, 2020 at 12:56 PM Serge Semin
> <Sergey.Semin@...kalelectronics.ru> wrote:
>>
>> On Mon, May 18, 2020 at 12:51:15PM +0200, Rafael J. Wysocki wrote:
>>> On Mon, May 18, 2020 at 12:46 PM Serge Semin
>>> <Sergey.Semin@...kalelectronics.ru> wrote:
>>>>
>>>> On Mon, May 18, 2020 at 12:41:19PM +0200, Rafael J. Wysocki wrote:
>>>>> On Monday, May 18, 2020 12:31:02 PM CEST Serge Semin wrote:
>>>>>> On Mon, May 18, 2020 at 03:54:15PM +0530, Viresh Kumar wrote:
>>>>>>> On 18-05-20, 12:22, Rafael J. Wysocki wrote:
>>>>>>>> On Monday, May 18, 2020 12:11:09 PM CEST Viresh Kumar wrote:
>>>>>>>>> On 18-05-20, 11:53, Rafael J. Wysocki wrote:
>>>>>>>>>> That said if you really only want it to return 0 on success, you may as well
>>>>>>>>>> add a ret = 0; statement (with a comment explaining why it is needed) after
>>>>>>>>>> the last break in the loop.
>>>>>>>>>
>>>>>>>>> That can be done as well, but will be a bit less efficient as the loop
>>>>>>>>> will execute once for each policy, and so the statement will run
>>>>>>>>> multiple times. Though it isn't going to add any significant latency
>>>>>>>>> in the code.
>>>>>>>>
>>>>>>>> Right.
>>>>>>>>
>>>>>>>> However, the logic in this entire function looks somewhat less than
>>>>>>>> straightforward to me, because it looks like it should return an
>>>>>>>> error on the first policy without a frequency table (having a frequency
>>>>>>>> table depends on the driver and that is the same for all policies, so it
>>>>>>>> is pointless to iterate any further in that case).
>>>>>>>>
>>>>>>>> Also, the error should not be -EINVAL, because that means "invalid
>>>>>>>> argument" which would be the state value.
>>>>>>>>
>>>>>>>> So I would do something like this:
>>>>>>>>
>>>>>>>> ---
>>>>>>>>  drivers/cpufreq/cpufreq.c |   11 ++++++-----
>>>>>>>>  1 file changed, 6 insertions(+), 5 deletions(-)
>>>>>>>>
>>>>>>>> Index: linux-pm/drivers/cpufreq/cpufreq.c
>>>>>>>> ===================================================================
>>>>>>>> --- linux-pm.orig/drivers/cpufreq/cpufreq.c
>>>>>>>> +++ linux-pm/drivers/cpufreq/cpufreq.c
>>>>>>>> @@ -2535,26 +2535,27 @@ EXPORT_SYMBOL_GPL(cpufreq_update_limits)
>>>>>>>>  static int cpufreq_boost_set_sw(int state)
>>>>>>>>  {
>>>>>>>>         struct cpufreq_policy *policy;
>>>>>>>> -       int ret = -EINVAL;
>>>>>>>>
>>>>>>>>         for_each_active_policy(policy) {
>>>>>>>> +               int ret;
>>>>>>>> +
>>>>>>>>                 if (!policy->freq_table)
>>>>>>>> -                       continue;
>>>>>>>> +                       return -ENXIO;
>>>>>>>>
>>>>>>>>                 ret = cpufreq_frequency_table_cpuinfo(policy,
>>>>>>>>                                                       policy->freq_table);
>>>>>>>>                 if (ret) {
>>>>>>>>                         pr_err("%s: Policy frequency update failed\n",
>>>>>>>>                                __func__);
>>>>>>>> -                       break;
>>>>>>>> +                       return ret;
>>>>>>>>                 }
>>>>>>>>
>>>>>>>>                 ret = freq_qos_update_request(policy->max_freq_req, policy->max);
>>>>>>>>                 if (ret < 0)
>>>>>>>> -                       break;
>>>>>>>> +                       return ret;
>>>>>>>>         }
>>>>>>>>
>>>>>>>> -       return ret;
>>>>>>>> +       return 0;
>>>>>>>>  }
>>>>>>>>
>>>>>>>>  int cpufreq_boost_trigger_state(int state)
>>>>>>>
>>>>>>> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
>>>>>>
>>>>>> Ok. Thanks for the comments. Shall I resend the patch with update Rafael
>>>>>> suggests or you'll merge the Rafael's fix in yourself?
>>>>>
>>>>> I'll apply the fix directly, thanks!
>>>>
>>>> Great. Is it going to be available in the repo:
>>>> https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git/
>>>> ?
>>>
>>> Yes, it is.  Please see the bleeding-edge branch in there, thanks!

Thanks for CCing me. I will write my next version based on this branch.

Thanks,
Xiongfeng

>>
>> No credits with at least Reported-by tag? That's sad.(
> 
> OK, done now, but you are not the only reported of it, so I've added
> the other reporter too.
> 
> Thanks!
> 
> .
>