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

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Message-ID: <CACRpkdacG4yxtZqwG5hKRY_8nY9qWeNPb-ZttMCnFH7ojZ3kCA@mail.gmail.com>
Date:   Thu, 2 Mar 2023 14:14:08 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Saravana Kannan <saravanak@...gle.com>
Cc:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.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 Thu, Mar 2, 2023 at 2:46 AM 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>

Works like a charm on U8500!
Tested-by: Linus Walleij <linus.walleij@...aro.org>
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>

Yours,
Linus Walleij