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

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Date:   Sun, 31 May 2020 08:57:54 +0900
From:   Chanwoo Choi <chanwoo@...nel.org>
To:     Sylwester Nawrocki <s.nawrocki@...sung.com>
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>
Subject: Re: [RFC PATCH v5 3/6] PM / devfreq: exynos-bus: Add registration of
 interconnect child device

Hi Sylwester,

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.

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics