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

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Message-ID: <20210616055841.4m7y6nxnxbgw5rzi@vireshk-i7>
Date:   Wed, 16 Jun 2021 11:28:41 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Hsin-Yi Wang <hsinyi@...omium.org>
Cc:     "Viresh Kumar )" <vireshk@...nel.org>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        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 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;
>  	}

How are you setting the required OPPs ? I mean when someone tries to
change frequency of a device which has some required-opps, who is
configuring those required OPPs ?

-- 
viresh