[PATCH v2 1/2] arm64: dts: amlogic: s4: assign mmc b clock to 24MHz

[Jerome Brunet]

On mer. 14 janv. 2026 at 10:05, Neil Armstrong <neil.armstrong at linaro.org> wrote:

> On 1/14/26 09:56, Jerome Brunet wrote:
>> The amlogic MMC driver operate with the assumption that MMC clock
>> is configured to provide 24MHz. It uses this path for low
>> rates such as 400kHz.
>> This assumption did hold true until but it now, but it is apparently
>> not the case with s4. The clock has been reported to provide 1GHz
>> instead. This is most likely due to how the bootloader is using the MMC
>> clock on this platform.
>> Regardless of why the MMC clock rate is 1GHz, if the MMC driver expects
>> 24MHz, the clock should be properly assigned, so assign it.
>> Reported-by: Nick Xie <nick at khadas.com>
>> Closes: https://lore.kernel.org/linux-amlogic/20260113011931.40424-1-nick@khadas.com/
>> Fixes: 3ab9d54b5d84 ("arm64: dts: amlogic: enable some device nodes for S4")
>> Tested-by: Nick Xie <nick at khadas.com>
>> Signed-off-by: Jerome Brunet <jbrunet at baylibre.com>
>> ---
>>   arch/arm64/boot/dts/amlogic/meson-s4.dtsi | 4 ++++
>>   1 file changed, 4 insertions(+)
>> diff --git a/arch/arm64/boot/dts/amlogic/meson-s4.dtsi
>> b/arch/arm64/boot/dts/amlogic/meson-s4.dtsi
>> index 9d99ed2994df..62538fd9db6b 100644
>> --- a/arch/arm64/boot/dts/amlogic/meson-s4.dtsi
>> +++ b/arch/arm64/boot/dts/amlogic/meson-s4.dtsi
>> @@ -838,6 +838,10 @@ sd: mmc at fe08a000 {
>>   			clock-names = "core", "clkin0", "clkin1";
>>   			resets = <&reset RESET_SD_EMMC_B>;
>>   			status = "disabled";
>> +
>> +			assigned-clocks = <&clkc_periphs CLKID_SD_EMMC_B>;
>> +			assigned-clock-parents = <0>;
>
> In this case, assigned-clock-parents should be dropped.
>

Dunno why I thought that was always required. I'll fix it and the other
instances

> Neil
>
>> +			assigned-clock-rates = <24000000>;
>>   		};
>>     		emmc: mmc at fe08c000 {
>> 

-- 
Jerome