linux-kernel - Re: [PATCH] opp: of: Allow lazy-linking of required-opps to non genpd

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Date:   Wed, 16 Jun 2021 17:47:14 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>,
        Hsin-Yi Wang <hsinyi@...omium.org>
Cc:     "Viresh Kumar )" <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "andrew-sh . cheng" <andrew-sh.cheng@...iatek.com>
Subject: Re: [PATCH] opp: of: Allow lazy-linking of required-opps to non
 genpd

On 6/16/21 4:55 PM, Viresh Kumar wrote:
> On 16-06-21, 13:33, Hsin-Yi Wang wrote:
>> Don't limit required_opp_table to genpd only. One possible use case is
>> cpufreq based devfreq governor, which can use required-opps property to
>> derive devfreq from cpufreq.
>>
>> Suggested-by: Chanwoo Choi <cw00.choi@...sung.com>
>> Signed-off-by: Hsin-Yi Wang <hsinyi@...omium.org>
>> ---
>> This is tested with the non genpd case mt8183-cci with passive
>> governor[1].
>> [1] https://patchwork.kernel.org/project/linux-mediatek/patch/1616499241-4906-2-git-send-email-andrew-sh.cheng@mediatek.com/
>> ---
>>  drivers/opp/of.c | 20 +-------------------
>>  1 file changed, 1 insertion(+), 19 deletions(-)
>>
>> diff --git a/drivers/opp/of.c b/drivers/opp/of.c
>> index aa75a1caf08a3..9573facce53a5 100644
>> --- a/drivers/opp/of.c
>> +++ b/drivers/opp/of.c
>> @@ -201,17 +201,6 @@ static void _opp_table_alloc_required_tables(struct opp_table *opp_table,
>>  			lazy = true;
>>  			continue;
>>  		}
>> -
>> -		/*
>> -		 * We only support genpd's OPPs in the "required-opps" for now,
>> -		 * as we don't know how much about other cases. Error out if the
>> -		 * required OPP doesn't belong to a genpd.
>> -		 */
>> -		if (!required_opp_tables[i]->is_genpd) {
>> -			dev_err(dev, "required-opp doesn't belong to genpd: %pOF\n",
>> -				required_np);
>> -			goto free_required_tables;
>> -		}
>>  	}
>>  
>>  	/* Let's do the linking later on */
>> @@ -379,13 +368,6 @@ static void lazy_link_required_opp_table(struct opp_table *new_table)
>>  	struct dev_pm_opp *opp;
>>  	int i, ret;
>>  
>> -	/*
>> -	 * We only support genpd's OPPs in the "required-opps" for now,
>> -	 * as we don't know much about other cases.
>> -	 */
>> -	if (!new_table->is_genpd)
>> -		return;
>> -
>>  	mutex_lock(&opp_table_lock);
>>  
>>  	list_for_each_entry_safe(opp_table, temp, &lazy_opp_tables, lazy) {
>> @@ -873,7 +855,7 @@ static struct dev_pm_opp *_opp_add_static_v2(struct opp_table *opp_table,
>>  		return ERR_PTR(-ENOMEM);
>>  
>>  	ret = _read_opp_key(new_opp, opp_table, np, &rate_not_available);
>> -	if (ret < 0 && !opp_table->is_genpd) {
>> +	if (ret < 0) {
>>  		dev_err(dev, "%s: opp key field not found\n", __func__);
>>  		goto free_opp;
>>  	}
> 
> Plus this and few changes to commit log.
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index e366218d6736..b335c077f215 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -893,6 +893,16 @@ static int _set_required_opps(struct device *dev,
>         if (!required_opp_tables)
>                 return 0;
>  
> +       /*
> +        * We only support genpd's OPPs in the "required-opps" for now, as we
> +        * don't know much about other use cases. Error out if the required OPP
> +        * doesn't belong to a genpd.
> +        */
> +       if (unlikely(!required_opp_tables[0]->is_genpd)) {
> +               dev_err(dev, "required-opps don't belong to a genpd\n");
> +               return -ENOENT;
> +       }
> +

If you add this checking statement, I think that 
when using dev_pm_opp_set_rate with required-opp property, it will be failed.

>         /* required-opps not fully initialized yet */
>         if (lazy_linking_pending(opp_table))
>                 return -EBUSY;
> 
> Applied. Thanks.
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics