How to fix the CPU frequency

stevenyu — Sat, 19 Jan 2019 09:06:43 GMT

Hi Support,

We found the CPU frequency is changing from time to time. We have checked Linux Reference Manual and realize it should be able to configure it, but we got following error. Do you know other way to fix the frequency setting ?

root@imx6ull14x14evk:~# echo interactive > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

root@imx6ull14x14evk:~# cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq
528000
root@imx6ull14x14evk:~# cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq
198000
root@imx6ull14x14evk:~# cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq
528000

root@imx6ull14x14evk:~# echo 528000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed
-sh: echo: write error: Invalid argument

===imx6ull-14x14-evk.dts===

&cpu0 {
/*
* on i.MX6ULL, no seperated VDD_ARM_IN and VDD_SOC_IN,
* to align with other platform and use the same cpufreq
* driver, still use the seperated OPP define for arm
* and soc.
*/
operating-points = <
/* kHz uV */
528000 1175000
396000 1175000
198000 1175000
>;
fsl,soc-operating-points = <
/* KHz uV */
528000 1175000
396000 1175000
198000 1175000
>;
arm-supply = <&sw1c_reg>;
soc-supply = <&sw1c_reg>;
fsl,arm-soc-shared = <1>;
};

Regards,

Steven Yu

Re: How to fix the CPU frequency

igorpadykov — Sun, 20 Jan 2019 23:00:42 GMT

Hi Steven

usage is described in sect.2.5.3.2 Software Operation attached Linux Manual:

Interactive CPU frequency governor is used which cannot be changed manually. To change CPU frequency
manually, the userspace CPU frequency governor can be used.

Best regards
igor
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

topic How to fix the CPU frequency in i.MX Processors

How to fix the CPU frequency

Re: How to fix the CPU frequency