linux-kernel - Re: [PATCH v2] clk: Mark a fwnode as initialized when using CLK_OF

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Date:   Wed, 1 Mar 2023 17:53:07 -0800
From:   Saravana Kannan <saravanak@...gle.com>
To:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Saravana Kannan <saravanak@...gle.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>, kernel-team@...roid.com,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] clk: Mark a fwnode as initialized when using
 CLK_OF_DECLARE() macro

On Wed, Mar 1, 2023 at 5:46 PM Saravana Kannan <saravanak@...gle.com> wrote:
>
> We already mark fwnodes as initialized when they are registered as clock
> providers. We do this so that fw_devlink can tell when a clock driver
> doesn't use the driver core framework to probe/initialize its device.
> This ensures fw_devlink doesn't block the consumers of such a clock
> provider indefinitely.
>
> However, some users of CLK_OF_DECLARE() macros don't use the same node
> that matches the macro as the node for the clock provider, but they
> initialize the entire node. To cover these cases, also mark the nodes
> that match the macros as initialized when the init callback function is
> called.
>
> An example of this is "stericsson,u8500-clks" that's handled using
> CLK_OF_DECLARE() and looks something like this:
>
> clocks {
>         compatible = "stericsson,u8500-clks";
>
>         prcmu_clk: prcmu-clock {
>                 #clock-cells = <1>;
>         };
>
>         prcc_pclk: prcc-periph-clock {
>                 #clock-cells = <2>;
>         };
>
>         prcc_kclk: prcc-kernel-clock {
>                 #clock-cells = <2>;
>         };
>
>         prcc_reset: prcc-reset-controller {
>                 #reset-cells = <2>;
>         };
>         ...
>         ...
> };
>
> This patch makes sure that "clocks" is marked as initialized so that
> fw_devlink knows that all nodes under it have been initialized.
>
> If the driver creates struct devices for some of the subnodes,
> fw_devlink is smart enough to know to wait for those devices to probe.
> So, no special handling is required for those cases.
>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Reported-by: Linus Walleij <linus.walleij@...aro.org>
> Link: https://lore.kernel.org/lkml/CACRpkdamxDX6EBVjKX5=D3rkHp17f5pwGdBVhzFU90-0MHY6dQ@mail.gmail.com/
> Fixes: 4a032827daa8 ("of: property: Simplify of_link_to_phandle()")
> Signed-off-by: Saravana Kannan <saravanak@...gle.com>

Linus, I changed the code a bit and I think this should work too. Can
you give it a shot please?

-Saravana

> ---
>  include/linux/clk-provider.h | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> index 842e72a5348f..c9f5276006a0 100644
> --- a/include/linux/clk-provider.h
> +++ b/include/linux/clk-provider.h
> @@ -1363,7 +1363,13 @@ struct clk_hw_onecell_data {
>         struct clk_hw *hws[];
>  };
>
> -#define CLK_OF_DECLARE(name, compat, fn) OF_DECLARE_1(clk, name, compat, fn)
> +#define CLK_OF_DECLARE(name, compat, fn) \
> +       static void __init name##_of_clk_init_declare(struct device_node *np) \
> +       {                                                               \
> +               fn(np);                                                 \
> +               fwnode_dev_initialized(of_fwnode_handle(np), true);     \
> +       }                                                               \
> +       OF_DECLARE_1(clk, name, compat, name##_of_clk_init_declare)
>
>  /*
>   * Use this macro when you have a driver that requires two initialization
> --
> 2.39.2.722.g9855ee24e9-goog
>