linux-kernel - Re: [PATCH] CHROMIUM: devfreq: rk3399: Clear edev->dev drvdata before enabling dfi

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Date:   Sat, 02 Sep 2017 09:51:41 +0800
From:   jeffy <jeffy.chen@...k-chips.com>
To:     Brian Norris <briannorris@...omium.org>
CC:     linux-kernel@...r.kernel.org, dbasehore@...omium.org,
        dianders@...omium.org, Chanwoo Choi <cw00.choi@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        linux-pm@...r.kernel.org
Subject: Re: [PATCH] CHROMIUM: devfreq: rk3399: Clear edev->dev drvdata before
 enabling dfi

hi brian,
On 09/02/2017 08:47 AM, Brian Norris wrote:
> On Sat, Sep 02, 2017 at 07:52:37AM +0800, Jeffy Chen wrote:
>> Currently we are using edev->dev drvdata to get rk3399-dmc data, but
>> it would be inited to edev in devfreq_event_add_edev.
>>
>> So we need to clear the edev->dev drvdata before enabling dfi, to
>> prevent dfi from getting the wrong rk3399-dmc data when the irq
>> triggered too early.
>
> Your description doesn't match your code. You say you're clearing
> evdev->dev driver data but...
>
>> Signed-off-by: Jeffy Chen <jeffy.chen@...k-chips.com>
>> ---
>>
>>   drivers/devfreq/rk3399_dmc.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/devfreq/rk3399_dmc.c b/drivers/devfreq/rk3399_dmc.c
>> index 1b89ebbad02c..12f9f03f349f 100644
>> --- a/drivers/devfreq/rk3399_dmc.c
>> +++ b/drivers/devfreq/rk3399_dmc.c
>> @@ -429,6 +429,7 @@ static int rk3399_dmcfreq_probe(struct platform_device *pdev)
>>
>>   	rk3399_devfreq_dmc_profile.initial_freq = data->rate;
>>
>> +	platform_set_drvdata(pdev, NULL);
>
> ...here you're only clearing the drvdata for the platform device. Is
> that a mistake? (Hint: that's not what you uploaded on the Chromium OS
> instance, where you presumably tested this.)
>
> And if you're really trying to do what your commit message says:
>
> We're having two different files fight over who owns the edev drvdata?
> That seems like a big no-no.
>
> We should work out who's the real owner of 'drvdata', and find some
> other solution for the others.

sorry, indeed...it turns out the upstream dmc driver is not using 
dfi(it's simple_onfemand below ;)...

so we don't need thus patch for upstream kernel...or maybe we should 
submit other cros patches(contains the one causes this issue, and this 
patch)
>
> Brian
>
>>   	data->devfreq = devm_devfreq_add_device(dev,
>>   					   &rk3399_devfreq_dmc_profile,
>>   					   "simple_ondemand",
>> --
>> 2.11.0
>>
>>
>
>
>