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

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Date:   Tue, 18 Jul 2017 10:35:49 +0000
From:   MyungJoo Ham <myungjoo.ham@...sung.com>
To:     "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>,
        Jeffy Chen <jeffy.chen@...k-chips.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

> 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?

It appears that your mali device driver's suspend/resume routines are
accessing "struct devfreq_dev_status" directly. Is this correct?


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()?


Cheers,
MyungJoo

ps. Where can I look at the mali-devfreq device driver? (I couldn't find it)