linux-kernel - Re: [PATCH v13 20/35] mtd: rawnand: tegra: Add runtime PM and OPP support

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Date:   Fri, 1 Oct 2021 16:24:32 +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 20/35] mtd: rawnand: tegra: Add runtime PM and OPP support

On Mon, 27 Sept 2021 at 00:42, Dmitry Osipenko <digetx@...il.com> wrote:
>
> The NAND on Tegra belongs to the core power domain and we're going to
> enable GENPD support for the core domain. Now NAND must be resumed using
> runtime PM API in order to initialize the NAND power state. Add runtime PM
> and OPP support to the NAND driver.
>
> Acked-by: Miquel Raynal <miquel.raynal@...tlin.com>
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  drivers/mtd/nand/raw/tegra_nand.c | 55 ++++++++++++++++++++++++++-----
>  1 file changed, 47 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/tegra_nand.c b/drivers/mtd/nand/raw/tegra_nand.c
> index 32431bbe69b8..098fcc9cb9df 100644
> --- a/drivers/mtd/nand/raw/tegra_nand.c
> +++ b/drivers/mtd/nand/raw/tegra_nand.c
> @@ -17,8 +17,11 @@
>  #include <linux/mtd/rawnand.h>
>  #include <linux/of.h>
>  #include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/reset.h>
>
> +#include <soc/tegra/common.h>
> +
>  #define COMMAND                                        0x00
>  #define   COMMAND_GO                           BIT(31)
>  #define   COMMAND_CLE                          BIT(30)
> @@ -1151,6 +1154,7 @@ static int tegra_nand_probe(struct platform_device *pdev)
>                 return -ENOMEM;
>
>         ctrl->dev = &pdev->dev;
> +       platform_set_drvdata(pdev, ctrl);
>         nand_controller_init(&ctrl->controller);
>         ctrl->controller.ops = &tegra_nand_controller_ops;
>
> @@ -1166,14 +1170,22 @@ static int tegra_nand_probe(struct platform_device *pdev)
>         if (IS_ERR(ctrl->clk))
>                 return PTR_ERR(ctrl->clk);
>
> -       err = clk_prepare_enable(ctrl->clk);
> +       err = devm_pm_runtime_enable(&pdev->dev);
> +       if (err)
> +               return err;
> +
> +       err = devm_tegra_core_dev_init_opp_table_common(&pdev->dev);
> +       if (err)
> +               return err;
> +
> +       err = pm_runtime_resume_and_get(&pdev->dev);
>         if (err)
>                 return err;
>
>         err = reset_control_reset(rst);
>         if (err) {
>                 dev_err(ctrl->dev, "Failed to reset HW: %d\n", err);
> -               goto err_disable_clk;
> +               goto err_put_pm;
>         }
>
>         writel_relaxed(HWSTATUS_CMD_DEFAULT, ctrl->regs + HWSTATUS_CMD);
> @@ -1188,21 +1200,19 @@ static int tegra_nand_probe(struct platform_device *pdev)
>                                dev_name(&pdev->dev), ctrl);
>         if (err) {
>                 dev_err(ctrl->dev, "Failed to get IRQ: %d\n", err);
> -               goto err_disable_clk;
> +               goto err_put_pm;
>         }
>
>         writel_relaxed(DMA_MST_CTRL_IS_DONE, ctrl->regs + DMA_MST_CTRL);
>
>         err = tegra_nand_chips_init(ctrl->dev, ctrl);
>         if (err)
> -               goto err_disable_clk;
> -
> -       platform_set_drvdata(pdev, ctrl);
> +               goto err_put_pm;
>

There is no corresponding call pm_runtime_put() here. Is it
intentional to always leave the device runtime resumed after ->probe()
has succeeded?

I noticed you included some comments about this for some other
drivers, as those needed more tweaks. Is that also the case for this
driver?

>         return 0;
>
> -err_disable_clk:
> -       clk_disable_unprepare(ctrl->clk);
> +err_put_pm:
> +       pm_runtime_put(ctrl->dev);
>         return err;
>  }
>

[...]

Kind regards
Uffe