i.MX ProcessorsのトピックRe: How to reduce CPU operating frequency on iMX8MM?

How to reduce CPU operating frequency on iMX8MM?

trongthinh — Tue, 28 Nov 2023 05:03:52 GMT

I built an embedded linux for my board, the board uses iMX8MM CPU.
BSP information is as follows:
manifest: imx-6.1.36-2.1.0.xml
git: https://github.com/nxp-imx/imx-manifest
branch: imx-linux-mickledore
Information about CPU clock is as follows:
scaling_governor: ondemand
scaling_available_frequencies: 1200000 1600000
scaling_available_governors: conservative ondemand userspace powersave performance schedutil
scaling_max_freq: 1600000
scaling_min_freq: 1200000
scaling_cur_freq: 1200000
So the system is running at 1200000, which is also the lowest frequency. However, I want it to be even lower, but I can't set other frequencies (example 400 Mhz, 800 Mhz). Please guide me how to make CPU run from 800 Mhz to 1.6 Ghz.

Re: How to reduce CPU operating frequency on iMX8MM?

joanxie — Tue, 28 Nov 2023 09:28:41 GMT

current bsp only support 1.8G, 1.6G and 1.2G

https://github.com/nxp-imx/linux-imx/blob/lf-6.1.y/arch/arm64/boot/dts/freescale/imx8mm.dtsi

if you need support more frequency, you can add in the table opp-table , and don't forget add the clock in the imx8mm_intpll_tbl of clk-imx8mm.c

Re: How to reduce CPU operating frequency on iMX8MM?

trongthinh — Wed, 29 Nov 2023 04:12:50 GMT

Hi joanxie,
I cannot find imx8mm_intpll_tbl in clk-imx8mm.c. Please checkthe file and show me where to add the clock.
https://github.com/nxp-imx/linux-imx/blob/lf-6.1.y/drivers/clk/imx/clk-imx8mm.c

Re: How to reduce CPU operating frequency on iMX8MM?

joanxie — Wed, 29 Nov 2023 06:53:42 GMT

for bsp 6.1 pls find imx_pll1416x_tbl

https://github.com/nxp-imx/linux-imx/blob/lf-6.1.y/drivers/clk/imx/clk-pll14xx.c