linux-kernel - Re: [PATCH v13 17/35] bus: tegra-gmi: Add runtime PM and OPP support

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Message-ID: <CAPDyKFoC7Kn9FPjAZLisSKWyYaXr1j2GnyQGNTVg_Dsuku-muA@mail.gmail.com>
Date:   Fri, 1 Oct 2021 16:18:59 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Viresh Kumar <vireshk@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        Mikko Perttunen <mperttunen@...dia.com>,
        Peter Chen <peter.chen@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, Nishanth Menon <nm@...com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Michael Turquette <mturquette@...libre.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-tegra <linux-tegra@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux USB List <linux-usb@...r.kernel.org>,
        linux-staging@...ts.linux.dev, linux-pwm@...r.kernel.org,
        linux-mmc <linux-mmc@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        DTML <devicetree@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        Mark Brown <broonie@...nel.org>,
        Vignesh Raghavendra <vigneshr@...com>,
        Richard Weinberger <richard@....at>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Lucas Stach <dev@...xeye.de>, Stefan Agner <stefan@...er.ch>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        David Heidelberg <david@...t.cz>
Subject: Re: [PATCH v13 17/35] bus: tegra-gmi: Add runtime PM and OPP support

On Mon, 27 Sept 2021 at 00:42, Dmitry Osipenko <digetx@...il.com> wrote:
>
> The GMI bus on Tegra belongs to the core power domain and we're going to
> enable GENPD support for the core domain. Now GMI must be resumed using
> runtime PM API in order to initialize the GMI power state. Add runtime PM
> and OPP support to the GMI driver.
>
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  drivers/bus/tegra-gmi.c | 52 ++++++++++++++++++++++++++++++++++++-----
>  1 file changed, 46 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/bus/tegra-gmi.c b/drivers/bus/tegra-gmi.c
> index a6570789f7af..72ef8a8c236b 100644
> --- a/drivers/bus/tegra-gmi.c
> +++ b/drivers/bus/tegra-gmi.c
> @@ -13,8 +13,11 @@
>  #include <linux/io.h>
>  #include <linux/module.h>
>  #include <linux/of_device.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/reset.h>
>
> +#include <soc/tegra/common.h>
> +
>  #define TEGRA_GMI_CONFIG               0x00
>  #define TEGRA_GMI_CONFIG_GO            BIT(31)
>  #define TEGRA_GMI_BUS_WIDTH_32BIT      BIT(30)
> @@ -54,9 +57,9 @@ static int tegra_gmi_enable(struct tegra_gmi *gmi)
>  {
>         int err;
>
> -       err = clk_prepare_enable(gmi->clk);
> -       if (err < 0) {
> -               dev_err(gmi->dev, "failed to enable clock: %d\n", err);
> +       err = pm_runtime_resume_and_get(gmi->dev);
> +       if (err) {
> +               pm_runtime_disable(gmi->dev);
>                 return err;
>         }
>
> @@ -83,7 +86,8 @@ static void tegra_gmi_disable(struct tegra_gmi *gmi)
>         writel(config, gmi->base + TEGRA_GMI_CONFIG);
>
>         reset_control_assert(gmi->rst);
> -       clk_disable_unprepare(gmi->clk);
> +
> +       pm_runtime_put(gmi->dev);
>  }
>
>  static int tegra_gmi_parse_dt(struct tegra_gmi *gmi)
> @@ -213,6 +217,7 @@ static int tegra_gmi_probe(struct platform_device *pdev)
>         if (!gmi)
>                 return -ENOMEM;
>
> +       platform_set_drvdata(pdev, gmi);
>         gmi->dev = dev;
>
>         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> @@ -232,6 +237,14 @@ static int tegra_gmi_probe(struct platform_device *pdev)
>                 return PTR_ERR(gmi->rst);
>         }
>
> +       err = devm_pm_runtime_enable(gmi->dev);
> +       if (err)
> +               return err;
> +
> +       err = devm_tegra_core_dev_init_opp_table_common(&pdev->dev);
> +       if (err)
> +               return err;
> +
>         err = tegra_gmi_parse_dt(gmi);
>         if (err)
>                 return err;
> @@ -247,8 +260,6 @@ static int tegra_gmi_probe(struct platform_device *pdev)
>                 return err;
>         }
>
> -       platform_set_drvdata(pdev, gmi);
> -
>         return 0;
>  }
>
> @@ -262,6 +273,34 @@ static int tegra_gmi_remove(struct platform_device *pdev)

Similar comment as for patch13, for the ->remove() callback.

This problem, which sometimes also exists in the error path in
->probe() (according to my comments in patch13), seems to be a common
issue in the series. I will therefore not continue to repeat my
comment on this for the remaining patches in the series, I think I
have made my point. :-)

Kind regards
Uffe