Re: [PATCH v5 3/3] PM / devfreq: Add required OPPs support to passive governor

[Viresh Kumar]

On 03-02-21, 17:24, Hsin-Yi Wang wrote:
> From: Saravana Kannan <saravanak@xxxxxxxxxx>
> 
> Look at the required OPPs of the "parent" device to determine the OPP that
> is required from the slave device managed by the passive governor. This
> allows having mappings between a parent device and a slave device even when
> they don't have the same number of OPPs.
> 
> Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx>
> Acked-by: MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx>
> Acked-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx>
> Signed-off-by: Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx>
> ---
>  drivers/devfreq/governor_passive.c | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
> index 63332e4a65ae8..8d92b1964f9c3 100644
> --- a/drivers/devfreq/governor_passive.c
> +++ b/drivers/devfreq/governor_passive.c
> @@ -19,7 +19,7 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>  			= (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;
> +	struct dev_pm_opp *opp = NULL, *p_opp = NULL;

I would initialize p_opp to ERR_PTR(-ENODEV) to avoid using
IS_ERR_OR_NULL. There is no need to initialize opp as well.

>  	int i, count, ret = 0;
>  
>  	/*
> @@ -56,13 +56,20 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>  	 * list of parent device. Because in this case, *freq is temporary
>  	 * value which is decided by ondemand governor.
>  	 */
> -	opp = devfreq_recommended_opp(parent_devfreq->dev.parent, freq, 0);
> -	if (IS_ERR(opp)) {
> -		ret = PTR_ERR(opp);
> +	p_opp = devfreq_recommended_opp(parent_devfreq->dev.parent, freq, 0);
> +	if (IS_ERR(p_opp)) {
> +		ret = PTR_ERR(p_opp);
>  		goto out;

Perhaps just return from here, the goto is useless here.

>  	}
>  
> -	dev_pm_opp_put(opp);
> +	if (devfreq->opp_table && parent_devfreq->opp_table)
> +		opp = dev_pm_opp_xlate_required_opp(parent_devfreq->opp_table,
> +						    devfreq->opp_table, p_opp);
> +	if (opp) {

This needs to be part of the above if block itself, else the opp will
always be NULL, isn't it ?

> +		*freq = dev_pm_opp_get_freq(opp);
> +		dev_pm_opp_put(opp);
> +		goto out;
> +	}
>  
>  	/*
>  	 * Get the OPP table's index of decided freqeuncy by governor
> @@ -89,6 +96,9 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>  	*freq = child_freq;
>  
>  out:
> +	if (!IS_ERR_OR_NULL(opp))

you should be checking for p_opp here, isn't it ? And perhaps we don't
need this check as well as p_opp can't be invalid here.

> +		dev_pm_opp_put(p_opp);
> +
>  	return ret;
>  }
>  
> -- 
> 2.30.0.365.g02bc693789-goog

-- 
viresh