SOC Thermal

SoC Thermal Temperature

Reading the SOC Temperature

The mx8mm SOC has an internal temperature sensor that can be read. The temperature is reported in millidegrees Celsius:

root@imx8mm-var-dart:~# cat /sys/class/thermal/thermal_zone0/temp                                                                          
43000

Thermal Setpoints

The Linux kernel will throttle the CPU and GPU based on setpoints configured in the Linux device tree.

The following demonstrates how to read the setpoints for the imx8mp-var-dart with the 5.15-2.0.x-imx_var01 kernel branch, but is similar for all platforms and kernel versions:

root@imx8mp-var-dart:~# cat /sys/class/thermal/thermal_zone0/trip_point_0_temp
85000
root@imx8mp-var-dart:~# cat /sys/class/thermal/thermal_zone0/trip_point_1_temp
95000

As shown above, there are two thermal setpoints, 85C and 95C. The setpoints are configured in the device tree: https://github.com/varigit/linux-imx/blob/5.15-2.0.x-imx_var01/arch/arm64/boot/dts/freescale/imx8mp.dtsi#L507-L567.