linux-kernel - Re: [PATCH] clk: at91: sama5d2: Mark device OF

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Message-ID: <CAGETcx9CodHDeqSYM1zQXRi-p_rFUJQgwMtnuWeKvCt_B3dCOw@mail.gmail.com>
Date:   Thu, 28 Jan 2021 09:01:41 -0800
From:   Saravana Kannan <saravanak@...gle.com>
To:     Tudor Ambarus <tudor.ambarus@...rochip.com>
Cc:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, nicolas.ferre@...rochip.com,
        alexandre.belloni@...tlin.com, ludovic.desroches@...rochip.com,
        claudiu.beznea@...rochip.com, mirq-linux@...e.qmqm.pl,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-clk@...r.kernel.org,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] clk: at91: sama5d2: Mark device OF_POPULATED after setup

On Thu, Jan 28, 2021 at 2:45 AM Tudor Ambarus
<tudor.ambarus@...rochip.com> wrote:
>
> The sama5d2 requires the clock provider initialized before timers.
> We can't use a platform driver for the sama5d2-pmc driver, as the
> platform_bus_init() is called later on, after time_init().
>
> As fw_devlink considers only devices, it does not know that the
> pmc is ready. Hence probing of devices that depend on it fail:
> probe deferral - supplier f0014000.pmc not ready
>
> Fix this by setting the OF_POPULATED flag for the sama5d2_pmc
> device node after successful setup. This will make
> of_link_to_phandle() ignore the sama5d2_pmc device node as a
> dependency, and consumer devices will be probed again.
>
> Fixes: e590474768f1cc04 ("driver core: Set fw_devlink=on by default")
> Signed-off-by: Tudor Ambarus <tudor.ambarus@...rochip.com>
> ---
> I'll be out of office, will check the rest of the at91 SoCs
> at the begining of next week.
>
>  drivers/clk/at91/sama5d2.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/clk/at91/sama5d2.c b/drivers/clk/at91/sama5d2.c
> index 9a5cbc7cd55a..5eea2b4a63dd 100644
> --- a/drivers/clk/at91/sama5d2.c
> +++ b/drivers/clk/at91/sama5d2.c
> @@ -367,6 +367,8 @@ static void __init sama5d2_pmc_setup(struct device_node *np)
>
>         of_clk_add_hw_provider(np, of_clk_hw_pmc_get, sama5d2_pmc);
>
> +       of_node_set_flag(np, OF_POPULATED);
> +
>         return;

Hi Tudor,

Thanks for looking into this.

I already accounted for early clocks like this when I designed
fw_devlink. Each driver shouldn't need to set OF_POPULATED.
drivers/clk/clk.c already does this for you.

I think the problem is that your driver is using
CLK_OF_DECLARE_DRIVER() instead of CLK_OF_DECLARE(). The comments for
CLK_OF_DECLARE_DRIVER() says:
/*
 * Use this macro when you have a driver that requires two initialization
 * routines, one at of_clk_init(), and one at platform device probe
 */

In your case, you are explicitly NOT having a driver bind to this
clock later. So you shouldn't be using CLK_OF_DECLARE() instead.

Thanks,
Saravana