linux-kernel - Re: [PATCH v2 1/5] clk: Respect CLK_OPS_PARENT

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Message-ID: <CAGXv+5F_xeC_sGNB9Aev4CQbC_8Vo4YA1u7K60oKu8PseL=Qhw@mail.gmail.com>
Date: Thu, 9 Oct 2025 15:07:55 +0800
From: Chen-Yu Tsai <wenst@...omium.org>
To: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
	Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, 
	Dong Aisheng <aisheng.dong@....com>, Matthias Brugger <matthias.bgg@...il.com>, 
	Yassine Oudjana <y.oudjana@...tonmail.com>, Laura Nao <laura.nao@...labora.com>, 
	Nícolas F. R. A. Prado <nfraprado@...labora.com>, 
	Chia-I Wu <olvaffe@...il.com>, kernel@...labora.com, linux-clk@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-mediatek@...ts.infradead.org, Stephen Boyd <sboyd@...eaurora.org>
Subject: Re: [PATCH v2 1/5] clk: Respect CLK_OPS_PARENT_ENABLE during recalc

On Thu, Oct 9, 2025 at 12:07 AM Nicolas Frattaroli
<nicolas.frattaroli@...labora.com> wrote:
>
> When CLK_OPS_PARENT_ENABLE was introduced, it guarded various clock
> operations, such as setting the rate or switching parents. However,
> another operation that can and often does touch actual hardware state is
> recalc_rate, which may also be affected by such a dependency.
>
> Add parent enables/disables where the recalc_rate op is called directly.
>
> Fixes: fc8726a2c021 ("clk: core: support clocks which requires parents enable (part 2)")
> Fixes: a4b3518d146f ("clk: core: support clocks which requires parents enable (part 1)")
> Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>

Reviewed-by: Chen-Yu Tsai <wenst@...omium.org>

> ---
>  drivers/clk/clk.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
>
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 85d2f2481acf360f0618a4a382fb51250e9c2fc4..1b0f9d567f48e003497afc98df0c0d2ad244eb90 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -1921,7 +1921,14 @@ static unsigned long clk_recalc(struct clk_core *core,
>         unsigned long rate = parent_rate;
>
>         if (core->ops->recalc_rate && !clk_pm_runtime_get(core)) {
> +               if (core->flags & CLK_OPS_PARENT_ENABLE)
> +                       clk_core_prepare_enable(core->parent);
> +
>                 rate = core->ops->recalc_rate(core->hw, parent_rate);
> +
> +               if (core->flags & CLK_OPS_PARENT_ENABLE)
> +                       clk_core_disable_unprepare(core->parent);
> +
>                 clk_pm_runtime_put(core);
>         }
>         return rate;
> @@ -4031,6 +4038,9 @@ static int __clk_core_init(struct clk_core *core)
>          */
>         clk_core_update_duty_cycle_nolock(core);
>
> +       if (core->flags & CLK_OPS_PARENT_ENABLE)
> +               clk_core_prepare_enable(core->parent);
> +
>         /*
>          * Set clk's rate.  The preferred method is to use .recalc_rate.  For
>          * simple clocks and lazy developers the default fallback is to use the
> @@ -4046,6 +4056,9 @@ static int __clk_core_init(struct clk_core *core)
>                 rate = 0;
>         core->rate = core->req_rate = rate;
>
> +       if (core->flags & CLK_OPS_PARENT_ENABLE)
> +               clk_core_disable_unprepare(core->parent);
> +
>         /*
>          * Enable CLK_IS_CRITICAL clocks so newly added critical clocks
>          * don't get accidentally disabled when walking the orphan tree and
>
> --
> 2.51.0
>
>