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

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Date:   Mon, 1 Jun 2020 12:04:52 +0200
From:   Sylwester Nawrocki <s.nawrocki@...sung.com>
To:     Chanwoo Choi <chanwoo@...nel.org>
Cc:     Georgi Djakov <georgi.djakov@...aro.org>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        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

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, 
Sylwester