linux-kernel - Re: [PATCH v1] of: platform: Batch fwnode parsing in the init

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Date:   Fri, 2 Oct 2020 09:07:55 -0500
From:   Rob Herring <robh+dt@...nel.org>
To:     Saravana Kannan <saravanak@...gle.com>
Cc:     Frank Rowand <frowand.list@...il.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Grygorii Strashko <grygorii.strashko@...com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        linux-omap <linux-omap@...r.kernel.org>,
        "open list:THERMAL" <linux-pm@...r.kernel.org>,
        Peter Ujfalusi <peter.ujfalusi@...com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Tomi Valkeinen <tomi.valkeinen@...com>,
        Tony Lindgren <tony@...mide.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Android Kernel Team <kernel-team@...roid.com>,
        devicetree@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] of: platform: Batch fwnode parsing in the
 init_machine() path

On Thu, Oct 1, 2020 at 5:59 PM Saravana Kannan <saravanak@...gle.com> wrote:
>
> When commit 93d2e4322aa7 ("of: platform: Batch fwnode parsing when
> adding all top level devices") optimized the fwnode parsing when all top
> level devices are added, it missed out optimizing this for platform
> where the top level devices are added through the init_machine() path.
>
> This commit does the optimization for all paths by simply moving the
> fw_devlink_pause/resume() inside of_platform_default_populate().
>
> Reported-by: Tomi Valkeinen <tomi.valkeinen@...com>
> Signed-off-by: Saravana Kannan <saravanak@...gle.com>
> ---
>  drivers/of/platform.c | 19 +++++++++++++++----
>  1 file changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 071f04da32c8..79972e49b539 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -501,8 +501,21 @@ int of_platform_default_populate(struct device_node *root,
>                                  const struct of_dev_auxdata *lookup,
>                                  struct device *parent)
>  {
> -       return of_platform_populate(root, of_default_bus_match_table, lookup,
> -                                   parent);
> +       int ret;
> +
> +       /*
> +        * fw_devlink_pause/resume() are only safe to be called around top
> +        * level device addition due to locking constraints.
> +        */
> +       if (!root)
> +               fw_devlink_pause();
> +
> +       ret = of_platform_populate(root, of_default_bus_match_table, lookup,
> +                                  parent);

of_platform_default_populate() vs. of_platform_populate() is just a
different match table. I don't think the behavior should otherwise be
different.

There's also of_platform_probe() which has slightly different matching
behavior. It should not behave differently either with respect to
devlinks.

Rob