How to change the CPU clock frequency on STM32MP157F-EV1 board from 650MHz to 800MHz?

[Subhajit.Ghosh]

I noticed that even if I create a new project using STM32CubeMX IDE for STM32MP157F-EV1 board, in the clock configuration, the MPUSS_CK is 650MHz. In Linux, I can see the CPU frequency is 650MHz only. How can I clock the CPU to 800MHz as supported by the SoC?

[Olivier GALLIEN · Accepted solution]

Hi @Subhajit.Ghosh​ ,

Which version of CubeMX and OpenSTLinux are you using ?

STM32MP157F-EV1 require at least OSTL Openstlinux-5.4-dunfell-mp1-20-06-24  and CubeMX V6.0

Did you test with the default Starter Package provided ?

If not already done you can refer to :

https://wiki.st.com/stm32mpu/wiki/How_to_change_the_CPU_frequency

Olivier

[Subhajit.Ghosh]

Hi Olivier,

Apologies for replying late. Thanks for the link.

Did a little bit of digging and found the same link which you have shared and managed to fix the issue.

Yes, we are using the Dunfell release.

The issue was:

We started initial development using the stm32mp157c variant which supports 650MHz.

We were using the device tree source file for tf-a spitted out CubeMX for the "c" variant

in which "stm32mp15xc.dtsi" was included, now the OPP table in this only contains definitions for 650MHz.

After inclusion of "stm32mp15xf.dtsi" for tf-a, there are two operating points now - 400MHz and 800MHz

as per the well written article in the link.

For testing did the following from userspace:

## This shows the current frequency in KHz, below output shows that the CPU is running in 400MHz ##

# cat /sys/devices/system/cpu/cpufreq/policy0/scaling_cur_freq

400000

## This shows the CPU frequency scaling policies available in the linux kernel

# cat /sys/devices/system/cpu/cpufreq/policy0/scaling_available_governors

conservative userspace powersave ondemand performance schedutil 

## This shows which policy is currently active.

# cat /sys/devices/system/cpu/cpufreq/policy0/scaling_governor

ondemand

## This changes the policy to "userspace", so that user can manually input the frequency.

# echo userspace > /sys/devices/system/cpu/cpufreq/policy0/scaling_governor

## Now we can manually change the frequency to 800MHz.

# echo 800000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_setspeed 

## This shows that the current CPU frequency is switched to 800MHz.

# cat /sys/devices/system/cpu/cpufreq/policy0/scaling_cur_freq

800000

Regards,

Subhajit Ghosh