lower imx8mm evk cpu speed

[lee19830115]

Hello, I wanted to reduce CPU frequency to be less than 1 GHz. There is a similar question that someone asked a few years ago. https://community.nxp.com/t5/i-MX-Processors/Lower-CPU-frequency-on-imx8mm/td-p/955456. But the patch doesn't work for me. I am on imx-5.10.9-1.0.0.xml. The supported frequencies are 1.2, 1.6 and 1.8 GHz on imx8mm evk. How can I lower the cpu frequencies? Thanks.

[josephzhou1]

detail steps please 

[Rita_Wang]

For the L5.10.9-1.0.0 version BSP structure is not the same with the 4.9.98_2.0.0, so you can not use the patch you mentioned above. Add the 1 GHz node in the dts.

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm64/boot/dts/freescale/imx8mm.dtsi?...

a53_opp_table: opp-table {
		compatible = "operating-points-v2";
		opp-shared;

		opp-1200000000 {
			opp-hz = /bits/ 64 <1200000000>;
			opp-microvolt = <850000>;
			opp-supported-hw = <0xe>, <0x7>;
			clock-latency-ns = <150000>;
			opp-suspend;
		};

		opp-1600000000 {
			opp-hz = /bits/ 64 <1600000000>;
			opp-microvolt = <950000>;
			opp-supported-hw = <0xc>, <0x7>;
			clock-latency-ns = <150000>;
			opp-suspend;
		};

		opp-1800000000 {
			opp-hz = /bits/ 64 <1800000000>;
			opp-microvolt = <1000000>;
			opp-supported-hw = <0x8>, <0x3>;
			clock-latency-ns = <150000>;
			opp-suspend;
		};
	};

[lee19830115]

Thanks for clarification. Is it possible to set the cpu frequency to 800M or 600 M or even lower speed? If possible, then how? Modify the app-table? Thanks.

[Rita_Wang]

Yes, the method is the same, you can try it.