[PATCH 1/2] arm64: dts: imx8mm-beacon: Fix HS400 USDHC clock speed

From: Adam Ford
Date: Fri Jun 20 2025 - 17:35:06 EST


The reference manual for the i.MX8MM states the clock rate in
MMC mode is 1/2 of the input clock, therefore to properly run
at HS400 rates, the input clock must be 400MHz to operate at
200MHz. Currently the clock is set to 200MHz which is half the
rate it should be, so the throughput is half of what it should be
for HS400 operation.

Fixes: 593816fa2f35 ("arm64: dts: imx: Add Beacon i.MX8m-Mini development kit")
Signed-off-by: Adam Ford <aford173@xxxxxxxxx>

diff --git a/arch/arm64/boot/dts/freescale/imx8mm-beacon-som.dtsi b/arch/arm64/boot/dts/freescale/imx8mm-beacon-som.dtsi
index 21bcd82fd092..8287a7f66ed3 100644
--- a/arch/arm64/boot/dts/freescale/imx8mm-beacon-som.dtsi
+++ b/arch/arm64/boot/dts/freescale/imx8mm-beacon-som.dtsi
@@ -294,6 +294,8 @@ &usdhc3 {
pinctrl-0 = <&pinctrl_usdhc3>;
pinctrl-1 = <&pinctrl_usdhc3_100mhz>;
pinctrl-2 = <&pinctrl_usdhc3_200mhz>;
+ assigned-clocks = <&clk IMX8MM_CLK_USDHC3>;
+ assigned-clock-rates = <400000000>;
bus-width = <8>;
non-removable;
status = "okay";
--
2.48.1