Re: [PATCH v2 1/5] clk: Respect CLK_OPS_PARENT_ENABLE during recalc

Chen-Yu Tsai
2025-10-09T07:08:13Z

On Thu, Oct 9, 2025 at 12:07 AM Nicolas Frattaroli
<nicolas.frattaroli@collabora.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@collabora.com>

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