linux-kernel - Re: [PATCH v2 29/48] soc/tegra: pmc: Link domains to the parent Core domain

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Date:   Tue, 12 Jan 2021 19:22:17 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Kevin Hilman <khilman@...nel.org>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        Viresh Kumar <vireshk@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-tegra <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH v2 29/48] soc/tegra: pmc: Link domains to the parent Core
 domain

12.01.2021 16:30, Ulf Hansson пишет:
> - trimmed cc-list
> 
> On Thu, 17 Dec 2020 at 19:07, Dmitry Osipenko <digetx@...il.com> wrote:
>>
>> The Core domain is a parent of PMC power domains, hence PMC domains
>> should be set up as a sub-domains of the parent (Core) domain if
>> "power-domains" phandle presents in a device-tree node of PMC domain.
>>
>> This allows to propagate GENPD performance changes to the parent Core
>> domain if performance change is applied to PMC domain.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
>> ---
>>  drivers/soc/tegra/pmc.c | 19 +++++++++++++++++++
>>  1 file changed, 19 insertions(+)
>>
>> diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
>> index 4f96dc7745c4..1a659d1c06d7 100644
>> --- a/drivers/soc/tegra/pmc.c
>> +++ b/drivers/soc/tegra/pmc.c
>> @@ -1236,6 +1236,7 @@ static int tegra_powergate_add(struct tegra_pmc *pmc, struct device_node *np)
>>  static int tegra_powergate_init(struct tegra_pmc *pmc,
>>                                 struct device_node *parent)
>>  {
>> +       struct of_phandle_args child_args, parent_args;
>>         struct device_node *np, *child;
>>         int err = 0;
>>
>> @@ -1249,6 +1250,24 @@ static int tegra_powergate_init(struct tegra_pmc *pmc,
>>                         of_node_put(child);
>>                         break;
>>                 }
>> +
>> +               if (of_parse_phandle_with_args(child, "power-domains",
>> +                                              "#power-domain-cells",
>> +                                              0, &parent_args))
>> +                       continue;
>> +
>> +               child_args.np = child;
>> +               child_args.args_count = 0;
>> +
>> +               err = of_genpd_add_subdomain(&parent_args, &child_args);
>> +               of_node_put(parent_args.np);
>> +               if (err) {
>> +                       if (err == -ENOENT)
>> +                               err = -EPROBE_DEFER;
> 
> Okay. So this special error treatment is needed because
> of_genpd_add_subdomain may return -ENOENT, in case the providers for
> the parent-domain and child-domain haven't been registered yet.
> 
> I suggest we move this into of_genpd_add_subdomain() instead, thus
> letting it return -EPROBE_DEFER when there are parent/child nodes
> specified in DT, but the providers are lacking.

Alright