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

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Date:   Tue, 22 Jun 2021 11:35:48 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     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, cwchoi00@...il.com, 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

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".

> +	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/

>  	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().