Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH v2 29/48] soc/tegra: pmc: Link domains to the parent Core
 domain
To:     Ulf Hansson <ulf.hansson@linaro.org>
Cc:     Thierry Reding <thierry.reding@gmail.com>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Kevin Hilman <khilman@kernel.org>,
        Peter De Schrijver <pdeschrijver@nvidia.com>,
        Viresh Kumar <vireshk@kernel.org>,
        Stephen Boyd <sboyd@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-tegra <linux-tegra@vger.kernel.org>
References: <20201217180638.22748-1-digetx@gmail.com>
 <20201217180638.22748-30-digetx@gmail.com>
 <CAPDyKFrj-8WwK1U7KJaCiWkt2bsohgoEnqhQ4sgwjZzZfX2iMA@mail.gmail.com>
From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <9feb43dc-1303-4207-6bc9-a3202696acd2@gmail.com>
Date:   Tue, 12 Jan 2021 19:22:17 +0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.4.2
MIME-Version: 1.0
In-Reply-To: <CAPDyKFrj-8WwK1U7KJaCiWkt2bsohgoEnqhQ4sgwjZzZfX2iMA@mail.gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Precedence: bulk

12.01.2021 16:30, Ulf Hansson пишет:
> - trimmed cc-list
> 
> On Thu, 17 Dec 2020 at 19:07, Dmitry Osipenko <digetx@gmail.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@gmail.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