linux-kernel - Re: [PATCH/RFC] soc: renesas: rcar-sysc: Mark device node OF

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Date:   Wed, 20 Jan 2021 09:09:09 -0800
From:   Saravana Kannan <saravanak@...gle.com>
To:     Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Marc Zyngier <maz@...nel.org>,
        Kevin Hilman <khilman@...libre.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH/RFC] soc: renesas: rcar-sysc: Mark device node
 OF_POPULATED after init

On Wed, Jan 20, 2021 at 6:23 AM Geert Uytterhoeven
<geert+renesas@...der.be> wrote:
>
> The R-Car System Controller (SYSC) driver registers PM domains from an
> early_initcall().  It does not use a platform driver, as secondary CPU
> startup on R-Car H1 needs to control the CPU power domains, before
> initialization of the driver framework.
>
> As fw_devlink only considers platform devices,

Correction. It only considers devices. As in, devices on all types of
busses are supported.

> it does not know that the
> System Controller is ready.  Hence probing of on-chip devices that are
> part of the SYSC PM domain fail:
>
>     probe deferral - supplier e6180000.system-controller not ready
>
> Fix this by setting the OF_POPULATED flag for the SYSC device node after
> successful initialization.  This will make of_link_to_phandle() ignore
> the SYSC device node as a dependency, and consumer devices will be
> probed again.

It'd still be nice if you could (maybe in a later patch), at least
probe all the power domains that aren't really needed this early.
Using the driver core framework (when it's possible), gives you nice
things :)

+Rob. I know he hates people using OF_POPULATED, but I think this case
is reasonable and want to make sure he's aware of this.

Once you fix my commit nitpick, you can add:
Reviewed-by: Saravana Kannan <saravanak@...gle.com>

-Saravana

>
> Fixes: e590474768f1cc04 ("driver core: Set fw_devlink=on by default")
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
> ---
>  drivers/soc/renesas/rcar-sysc.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/soc/renesas/rcar-sysc.c b/drivers/soc/renesas/rcar-sysc.c
> index 9b235fc900273405..a00bb098e1fe7488 100644
> --- a/drivers/soc/renesas/rcar-sysc.c
> +++ b/drivers/soc/renesas/rcar-sysc.c
> @@ -439,6 +439,8 @@ static int __init rcar_sysc_pd_init(void)
>         }
>
>         error = of_genpd_add_provider_onecell(np, &domains->onecell_data);
> +       if (!error)
> +               of_node_set_flag(np, OF_POPULATED);
>
>  out_put:
>         of_node_put(np);
> --
> 2.25.1
>