linux-kernel - Re: [RFC PATCH v5 3/6] PM / devfreq: exynos-bus: Add registration of interconnect child device

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Message-ID: <7a3840c7-fbfb-112e-46b6-97871da710e8@samsung.com>
Date:   Tue, 2 Jun 2020 09:50:52 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Sylwester Nawrocki <s.nawrocki@...sung.com>,
        Chanwoo Choi <chanwoo@...nel.org>
Cc:     Georgi Djakov <georgi.djakov@...aro.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Artur Świgoń <a.swigon@...sung.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>, inki.dae@...sung.com,
        Seung-Woo Kim <sw0312.kim@...sung.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Rob Herring <robh+dt@...nel.org>,
        devicetree <devicetree@...r.kernel.org>
Subject: Re: [RFC PATCH v5 3/6] PM / devfreq: exynos-bus: Add registration
 of interconnect child device

Hi Sylwester,

On 6/1/20 7:04 PM, Sylwester Nawrocki wrote:
> Cc: Rob, devicetree ML
> 
> On 31.05.2020 01:57, Chanwoo Choi wrote:
>> On Sat, May 30, 2020 at 1:33 AM Sylwester Nawrocki
>> <s.nawrocki@...sung.com> wrote:
>>>
>>> This patch adds registration of a child platform device for the exynos
>>> interconnect driver. It is assumed that the interconnect provider will
>>> only be needed when #interconnect-cells property is present in the bus
>>> DT node, hence the child device will be created only when such a property
>>> is present.
>>>
>>> Signed-off-by: Sylwester Nawrocki <s.nawrocki@...sung.com>
>>>
>>> Changes for v5:
>>>  - new patch.
>>> ---
>>>  drivers/devfreq/exynos-bus.c | 17 +++++++++++++++++
>>>  1 file changed, 17 insertions(+)
>>>
>>> diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c
>>> index 8fa8eb5..856e37d 100644
>>> --- a/drivers/devfreq/exynos-bus.c
>>> +++ b/drivers/devfreq/exynos-bus.c
>>> @@ -24,6 +24,7 @@
>>>
>>>  struct exynos_bus {
>>>         struct device *dev;
>>> +       struct platform_device *icc_pdev;
>>>
>>>         struct devfreq *devfreq;
>>>         struct devfreq_event_dev **edev;
>>> @@ -156,6 +157,8 @@ static void exynos_bus_exit(struct device *dev)
>>>         if (ret < 0)
>>>                 dev_warn(dev, "failed to disable the devfreq-event devices\n");
>>>
>>> +       platform_device_unregister(bus->icc_pdev);
>>> +
>>>         dev_pm_opp_of_remove_table(dev);
>>>         clk_disable_unprepare(bus->clk);
>>>         if (bus->opp_table) {
>>> @@ -168,6 +171,8 @@ static void exynos_bus_passive_exit(struct device *dev)
>>>  {
>>>         struct exynos_bus *bus = dev_get_drvdata(dev);
>>>
>>> +       platform_device_unregister(bus->icc_pdev);
>>> +
>>>         dev_pm_opp_of_remove_table(dev);
>>>         clk_disable_unprepare(bus->clk);
>>>  }
>>> @@ -431,6 +436,18 @@ static int exynos_bus_probe(struct platform_device *pdev)
>>>         if (ret < 0)
>>>                 goto err;
>>>
>>> +       /* Create child platform device for the interconnect provider */
>>> +       if (of_get_property(dev->of_node, "#interconnect-cells", NULL)) {
>>> +                   bus->icc_pdev = platform_device_register_data(
>>> +                                               dev, "exynos-generic-icc",
>>> +                                               PLATFORM_DEVID_AUTO, NULL, 0);
>>> +
>>> +                   if (IS_ERR(bus->icc_pdev)) {
>>> +                           ret = PTR_ERR(bus->icc_pdev);
>>> +                           goto err;
>>> +                   }
>>> +       }
>>> +
>>>         max_state = bus->devfreq->profile->max_state;
>>>         min_freq = (bus->devfreq->profile->freq_table[0] / 1000);
>>>         max_freq = (bus->devfreq->profile->freq_table[max_state - 1] / 1000);
>>> --
>>> 2.7.4
>>>
>>
>> It looks like very similar like the registering the interconnect
>> device of imx-bus.c
>> and I already reviewed and agreed this approach.
>>
>> Acked-by: Chanwoo Choi <cw00.choi@...sung.com>
>>
>> nitpick: IMHO, I think that 'exynos-icc' is proper and simple without
>> 'generic' word.
>> If we need to add new icc compatible int the future, we will add
>> 'exynosXXXX-icc' new compatible.
>> But, I'm not forcing it. just opinion. Anyway, I agree this approach.
> 
> Thanks for review. I will change the name to exynos-icc in next version, 
> as I commented at other patch, it is not part of any DT binding, 
> it is just for device/driver matching between devfreq and interconnect.

Thanks. I have not any objection to use either 'exynos-generic-icc' 
or 'exynos-icc'. It is just my opinion. And on next version,
please add linux-pm mailing list to Cc.

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics