[PATCH 2/2] arm64: dts: imx8mn-beacon: Fix HS400 USDHC clock speed

Adam Ford aford173 at gmail.com
Fri Jun 20 14:34:46 PDT 2025


The reference manual for the i.MX8MN 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: 36ca3c8ccb53 ("arm64: dts: imx: Add Beacon i.MX8M Nano development kit")
Signed-off-by: Adam Ford <aford173 at gmail.com>

diff --git a/arch/arm64/boot/dts/freescale/imx8mn-beacon-som.dtsi b/arch/arm64/boot/dts/freescale/imx8mn-beacon-som.dtsi
index 67a99383a632..917b7d0007a7 100644
--- a/arch/arm64/boot/dts/freescale/imx8mn-beacon-som.dtsi
+++ b/arch/arm64/boot/dts/freescale/imx8mn-beacon-som.dtsi
@@ -305,6 +305,8 @@ &usdhc3 {
 	pinctrl-0 = <&pinctrl_usdhc3>;
 	pinctrl-1 = <&pinctrl_usdhc3_100mhz>;
 	pinctrl-2 = <&pinctrl_usdhc3_200mhz>;
+	assigned-clocks = <&clk IMX8MN_CLK_USDHC3>;
+	assigned-clock-rates = <400000000>;
 	bus-width = <8>;
 	non-removable;
 	status = "okay";
-- 
2.48.1




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