i.MX 8M Nano: Linux Kernel: Operation points (CPUFreq)

[Svenifax]

Hi NXP,

I found in the 5.4.24_2.1.0 Linux release for the i.MX 8M Nano that there are only three operation points supported: 1.2/1.4/1.5GHz.

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm64/boot/dts/freescale/imx8mn.dtsi?...

Device tree:

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

		opp-1200000000 {
			opp-hz = /bits/ 64 <1200000000>;
			opp-microvolt = <850000>;
			opp-supported-hw = <0xb00>, <0x7>;
			clock-latency-ns = <150000>;
			opp-suspend;
		};

		opp-1400000000 {
			opp-hz = /bits/ 64 <1400000000>;
			opp-microvolt = <950000>;
			opp-supported-hw = <0x300>, <0x7>;
			clock-latency-ns = <150000>;
			opp-suspend;
		};

		opp-1500000000 {
			opp-hz = /bits/ 64 <1500000000>;
			opp-microvolt = <1000000>;
			opp-supported-hw = <0x100>, <0x3>;
			clock-latency-ns = <150000>;
			opp-suspend;
		};
	};

I want to have much lower frequencies, how can I archive that? Where can I found the regarding information in the data manuals? Like opp-microvolt and opp-supported-hw?

Best regards,
Sven

[Bio_TICFSL]

Hello Svenifax,

These are the cpufreq that are available for the MX8MN and are part of kernel of the bsp, NXP don't have the opp/microvolt, however you can add more frequencies and add he opp-microvilt to it.

Regards

[Svenifax]

Hello NXP,

is there no information available about the missing infos?

To add an operating point, the relationship between frequency, voltage and register settings must be known.

This information should be part of the documentation. Where can I found this?

Best regards,
Sven

[Bio_TICFSL]

Hell, 

For all related to MX8MN in linux, You can view the Linux reference manual on your yocto documentation. otherwise you can view the reference manual of the chip.

Regards

[Svenifax]

Hello,

I checked the the following documents:

• i.MX 8M Nano Applications Processor Datasheet for Industrial Products (IMX8MNIEC) - Rev. 1, 03/2021
  
• i.MX 8M Nano Applications ProcessorReference Manual (IMX8MNRM) - Rev. 1, 11/2020
  
• i.MX Linux Reference Manual (IMXLXR) - Rev. LF5.10.35_2.0.0, 30 June 2021
  

I could not found any information between the relationship of cpu frequency, voltage and register settings.

Where can I found such information?

Best regards,
Sven