Re: [PATCH 2/2] clk: meson: s4: propagate rate requests through the CEC 32k muxes

[Jerome Brunet <jbrunet@baylibre.com>]

On dim. 25 oct. 2026 at 20:18, christian.koever-draxl@student.uibk.ac.at wrote:

> From: Christian Stefan Kövér-Draxl <ckoever@outlook.de>
>
> The AO-CEC driver asks its core clock for 32768 Hz. On S4 that request
> stops at ceca_32k_sel / cecb_32k_sel: both are muxes without
> CLK_SET_RATE_PARENT, so it never reaches the dual divider that can
> produce the rate, and probe fails with
>
>   meson-ao-cec fe044000.cec: core clock set rate failed
>   meson-ao-cec fe044000.cec: CEC controller registration failed
>
> The equivalent G12A mux, ao_cec_sel, carries the flag, which is why CEC
> works there. Add it to both S4 selectors.
>
> The other parent of these muxes is the RTC clock, which must not be
> reprogrammed on behalf of CEC, so boards should pin the mux parent to
> the dual divider with assigned-clock-parents.

Again, the change is OK in itself but if you are going to assign the
mux parents through assigned rate why, why don't you assign the parent
rate too ?

You are doing half the job in DT, half in the driver, that is kind of
odd.

>
> Only the CECA path was tested; CECB is the same defect in the
> duplicated block.
>
> Fixes: 57b55c76aaf1 ("clk: meson: S4: add support for Amlogic S4 SoC peripheral clock controller")
> Signed-off-by: Christian Stefan Kövér-Draxl <ckoever@outlook.de>
> ---
>  drivers/clk/meson/s4-peripherals.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/clk/meson/s4-peripherals.c b/drivers/clk/meson/s4-peripherals.c
> index 329cd526749e..8e303db6154c 100644
> --- a/drivers/clk/meson/s4-peripherals.c
> +++ b/drivers/clk/meson/s4-peripherals.c
> @@ -407,6 +407,7 @@ static struct clk_regmap s4_ceca_32k_sel = {
>  			&s4_rtc_clk.hw
>  		},
>  		.num_parents = 2,
> +		.flags = CLK_SET_RATE_PARENT,
>  	},
>  };
>  
> @@ -514,6 +515,7 @@ static struct clk_regmap s4_cecb_32k_sel = {
>  			&s4_rtc_clk.hw
>  		},
>  		.num_parents = 2,
> +		.flags = CLK_SET_RATE_PARENT,
>  	},
>  };
>  
> -- 
> 2.56.0
>
>
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-- 
Jerome

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