AM5716: MPU A15 CPU running frequency change unexpeced

Hello Semon,

This question is related to this one-> https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1527316/am5716-cinfigure-cpu-frequenc, correct?

Since they are very similar we can merge them.

1.

Semon Zhang said:

 1. currently hardware A15 default setting is on-demand low power mode, all other configurations are default setting, but through  cpuinfo_cur_freq to query CPU A15 frequency, some HW board is fixed 1.5G Hz, some are fixed 1.2G Hz, while some are 1.0G Hz, even some HW boards frequency jump between 1.2G hz and 1.5 Hz (query frequency every 1 minutes), it doesn't work as expeceted, please provide a document to describe the CPU work mode and its affection. what condition will trigger the CPU frequency change?

If I understand you correctly, the default set frequency varies per device, without any modification to the default EVM image, Is that the correct understanding?

I believe the system is expected to change its frequency on demand based on usage. See the following threads:
 * https://e2e.ti.com/support/processors-group/processors/f/processors-forum/581848/am5728-mpu-frequencies/2135780#2135780

 * https://e2e.ti.com/support/processors-group/processors/f/processors-forum/926010/am5749/3422056#3422056

The document that goes over Dynamic Voltage and Frequency Scaling (DVFS) is on the SDK Documentation: https://software-dl.ti.com/processor-sdk-linux/esd/docs/06_03_00_106/linux/Foundational_Components/Kernel/Kernel_Drivers/Power_Management.html

2.

Semon Zhang said:

provide a method to set CPU freqency fixed.

See documentation linked above.

3.

Semon Zhang said:

what's the relation between CPU powerr consumption and CPU frequency, is the a document?

In simple terms, the higher the frequency the more power the core uses.

Best,

Josue