linux-kernel - Re: [PATCH] devfreq: simple_ondemand: Update devfreq stats when governor started

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Date:   Tue, 18 Jul 2017 19:27:26 +0800
From:   jeffy <jeffy.chen@...k-chips.com>
To:     myungjoo.ham@...sung.com,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "rui.zhang@...el.com" <rui.zhang@...el.com>,
        "briannorris@...omium.org" <briannorris@...omium.org>,
        "javi.merino@...nel.org" <javi.merino@...nel.org>,
        "dianders@...omium.org" <dianders@...omium.org>,
        "lukasz.luba@....com" <lukasz.luba@....com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>
Subject: Re: [PATCH] devfreq: simple_ondemand: Update devfreq stats when governor
 started

hi Ham,

Thanks for your reply.

On 07/18/2017 06:35 PM, MyungJoo Ham wrote:
>> If governor suspends soon after started, it may not have the chance to
>> update devfreq stats, which leaves devfreq stats' current frequence be
>> zero.
>>
>> So when the thermal core tries to throttle the power, it would failed
>> to get the correct static power of current frequence and print these
>> warnings:
>> [    2.024735] core: dev_pm_opp_get_voltage: Invalid parameters
>> [    2.024743] mali ff9a0000.gpu: Failed to get voltage for frequency 0:
>> -34
>> ...
>> [    2.026320] core: dev_pm_opp_get_voltage: Invalid parameters
>> [    2.026327] mali ff9a0000.gpu: Failed to get voltage for frequency 0:
>> -34
>>
>> Update devfreq stats when governor started to avoid that.
>>
>> Signed-off-by: Jeffy Chen <jeffy.chen@...k-chips.com>
>
> How are you calling suspend/resume routins in the mali drivers?
>
i was porting mali driver from here:
https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-4.4/drivers/gpu/arm/midgard/mali_kbase_core_linux.c#4079
> It appears that your mali device driver's suspend/resume routines are
> accessing "struct devfreq_dev_status" directly. Is this correct?
>
no, but the suspend/resume would suspend/resume the governor.
>
> Plus, for MALI (if that assumption is correct), this issue might occur
> with other governors.
>
> If so, would it be better to put the first initializing call of
> devfreq_update_stats() at devfreq_add_device()?
>
right, that make sense. i put it here because the comment of this 
function said it should be called by governor, but you're right, it 
would be better this way, will send new version soon.
>
> Cheers,
> MyungJoo
>
> ps. Where can I look at the mali-devfreq device driver? (I couldn't find it)
sorry, i should mention that, please check above link :)
>
>
>
>