linux-kernel - Re: [PATCH 4/4] PM / devfreq: passive: Reduce duplicate code when passive

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Date:   Wed, 14 Jul 2021 04:31:06 +0900
From:   Chanwoo Choi <cwchoi00@...il.com>
To:     Matthias Kaehlcke <mka@...omium.org>,
        Chanwoo Choi <cw00.choi@...sung.com>
Cc:     andrew-sh.cheng@...iatek.com, hsinyi@...omium.org,
        sibis@...eaurora.org, saravanak@...gle.com,
        myungjoo.ham@...sung.com, kyungmin.park@...sung.com,
        chanwoo@...nel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] PM / devfreq: passive: Reduce duplicate code when
 passive_devfreq case

Hi Matthias,

On 21. 6. 23. 오전 3:35, Matthias Kaehlcke wrote:
> On Thu, Jun 17, 2021 at 03:05:46PM +0900, Chanwoo Choi wrote:
>> In order to keep the consistent coding style between passive_devfreq
>> and passive_cpufreq, use common code for handling required opp property.
>> Also remove the unneed conditional statement and unify the comment
>> of both passive_devfreq and passive_cpufreq when getting the target frequency.
>>
>> Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
>> ---
>>   drivers/devfreq/governor_passive.c | 80 ++++++------------------------
>>   1 file changed, 15 insertions(+), 65 deletions(-)
>>
>> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
>> index 07e864509b7e..7102cb7eb30d 100644
>> --- a/drivers/devfreq/governor_passive.c
>> +++ b/drivers/devfreq/governor_passive.c
>> @@ -91,66 +91,17 @@ static int get_target_freq_with_devfreq(struct devfreq *devfreq,
>>   	struct devfreq_passive_data *p_data
>>   			= (struct devfreq_passive_data *)devfreq->data;
>>   	struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
>> -	unsigned long child_freq = ULONG_MAX;
>> -	struct dev_pm_opp *opp, *p_opp;
>> -	int i, count;
>> -
>> -	/*
>> -	 * If the devfreq device with passive governor has the specific method
>> -	 * to determine the next frequency, should use the get_target_freq()
>> -	 * of struct devfreq_passive_data.
>> -	 */
>> -	if (p_data->get_target_freq)
>> -		return p_data->get_target_freq(devfreq, freq);
>> -
>> -	/*
>> -	 * If the parent and passive devfreq device uses the OPP table,
>> -	 * get the next frequency by using the OPP table.
>> -	 */
>> -
>> -	/*
>> -	 * - parent devfreq device uses the governors except for passive.
>> -	 * - passive devfreq device uses the passive governor.
>> -	 *
>> -	 * Each devfreq has the OPP table. After deciding the new frequency
>> -	 * from the governor of parent devfreq device, the passive governor
>> -	 * need to get the index of new frequency on OPP table of parent
>> -	 * device. And then the index is used for getting the suitable
>> -	 * new frequency for passive devfreq device.
>> -	 */
>> -	if (!devfreq->profile || !devfreq->profile->freq_table
>> -		|| devfreq->profile->max_state <= 0)
>> -		return -EINVAL;
>> -
>> -	/*
>> -	 * The passive governor have to get the correct frequency from OPP
>> -	 * list of parent device. Because in this case, *freq is temporary
>> -	 * value which is decided by ondemand governor.
>> -	 */
>> -	if (devfreq->opp_table && parent_devfreq->opp_table) {
>> -		p_opp = devfreq_recommended_opp(parent_devfreq->dev.parent,
>> -						freq, 0);
>> -		if (IS_ERR(p_opp))
>> -			return PTR_ERR(p_opp);
>> -
>> -		opp = dev_pm_opp_xlate_required_opp(parent_devfreq->opp_table,
>> -						    devfreq->opp_table, p_opp);
>> -		dev_pm_opp_put(p_opp);
>> -
>> -		if (IS_ERR(opp))
>> -			goto no_required_opp;
>> -
>> -		*freq = dev_pm_opp_get_freq(opp);
>> -		dev_pm_opp_put(opp);
>> -
>> -		return 0;
>> -	}
>> +	unsigned long target_freq;
>> +	int i;
>> +
>> +	/* Get target freq via required opps */
>> +	target_freq = get_taget_freq_by_required_opp(parent_devfreq->dev.parent,
>> +						parent_devfreq->opp_table,
>> +						devfreq->opp_table, *freq);
> 
> s/get_taget_freq_by_required_opp/get_target_freq_by_required_opp/
> 
> Also need to be fixed in "[3/4] PM / devfreq: Add cpu based scaling
> support to passive governor".

Thanks for catch. I'll fix it.

> 
>> +	if (target_freq)
>> +		goto out;
>>   
>> -no_required_opp:
>> -	/*
>> -	 * Get the OPP table's index of decided frequency by governor
>> -	 * of parent device.
>> -	 */
>> +	/* Use Interpolation if required opps is not available */
> 
> s/Interpolation/interpolation/

I'll fix it.

> 
>>   	for (i = 0; i < parent_devfreq->profile->max_state; i++)
>>   		if (parent_devfreq->profile->freq_table[i] == *freq)
>>   			break;
>> @@ -158,16 +109,15 @@ static int get_target_freq_with_devfreq(struct devfreq *devfreq,
>>   	if (i == parent_devfreq->profile->max_state)
>>   		return -EINVAL;
>>   
>> -	/* Get the suitable frequency by using index of parent device. */
>>   	if (i < devfreq->profile->max_state) {
>> -		child_freq = devfreq->profile->freq_table[i];
>> +		target_freq = devfreq->profile->freq_table[i];
>>   	} else {
>> -		count = devfreq->profile->max_state;
>> -		child_freq = devfreq->profile->freq_table[count - 1];
>> +		i = devfreq->profile->max_state;
>> +		target_freq = devfreq->profile->freq_table[i - 1];
>>   	}
>>   
>> -	/* Return the suitable frequency for passive device. */
>> -	*freq = child_freq;
>> +out:
>> +	*freq = target_freq;
> 
> You might want to split the child_freq => target_freq and commentary change into
> a separate patch, since it is not directly related with the switch to
> get_target_freq_by_required_opp().

OK. I will not change about child_freq -> target_freq.


-- 
Best Regards,
Samsung Electronics
Chanwoo Choi