Linux/AM5726: Thermal monitoring and frequency measurements

Hi,

Finally I could investigate some more about the linux kernel configuration.

My setup:

I got the latest linux source code from http://software-dl.ti.com/processor-sdk-linux-rt/esd/AM57X/latest/exports/am57xx-evm-linux-rt-sdk-src-03.03.00.04.tar.xz

On my target when I do `uname –a`

Linux sitara 4.4.41-rt50-g968d071ce9 #3 SMP PREEMPT RT Fri May 19 10:12:37 CEST 2017 armv7l GNU/Linux

So we are working on the same git commit.

I agree we have to disabled CONFIG_CPU_FREQ and CONFIG_CPU_IDLE to run the RT patched kernel. But we also would like to log the junction temperature to track the dependency of load, frequency and temperature. Until now we only found the possibility to read the temperature with <cat /sys/class/thermal/thermal_zone0/temp>  but this interface is only provided when TI_THERMAL is enabled. But TI_THERMAL depends on CPU_THERMAL which depends on CPU_FREQ.

So is there another way to track the temperature without enabling any configuration of the CPU Power Management?

Best regards,

Joakim

Hi Pavel,

Yes we are working with the ti-processor-sdk-linux-rt-am57xx-evm-03.03.00.04 on the AM572x IDK.

Pavel Botev said:

Other approach can be to disable CPU_THERMAL and CPU_FREQ from linux kernel, then to enable only thrermal management in user space through sysfs entries

/sys/class/thermal/thermal_zone0 is present but if I enable the thermal_zone0 ( echo -n "enabled" > /sys/class/thermal/thermal_zone0/mode)  it is still not possible to get the temperature.

cat: /sys/class/thermal/thermal_zone0/temp: Invalid argument

So this sysfs interface is only provided when TI_THERMAL is enabled as described above.

Do we miss something to activate this interface?

Thank you for the answer & regards Guy

PS. Joakim and me are working together on this problem.

Guy,

Guy Bilgerig said:

/sys/class/thermal/thermal_zone0 is present but if I enable the thermal_zone0 ( echo -n "enabled" > /sys/class/thermal/thermal_zone0/mode)  it is still not possible to get the temperature.

Can you check if "enabled" is actually set (cat the "mode" entry before and after "enabled")?

Do you have also the below path available?

/sys/devices/virtual/thermal/thermal_zone0/mode

Regards,
Pavel

Hi Pavel,

Yes the mode is afterwards enabled and also the /sys/devices/virtual/thermal is present.

root@sitara:/# cat /sys/class/thermal/thermal_zone0/mode
disabled
root@sitara:/# echo -n "enabled" > /sys/class/thermal/thermal_zone0/mode
root@sitara:/# cat /sys/class/thermal/thermal_zone0/mode
enabled
root@sitara:/# cat /sys/class/thermal/thermal_zone0/temp
cat: /sys/class/thermal/thermal_zone0/temp: Invalid argument
root@sitara:/#

root@sitara:/# cat /sys/devices/virtual/thermal/thermal_zone0/mode
enabled
root@sitara:/# cat /sys/devices/virtual/thermal/thermal_zone0/temp
cat: /sys/devices/virtual/thermal/thermal_zone0/temp: Invalid argument

Hi Pavel,

In another thread you recommended to use omapconf from TI. I saw that you also can use it to read out the temperature like this:

user@sitara:~/omapconf$ sudo omapconf show temp mpu
OMAPCONF (rev 1.73-nogit built Thu Jun 8 09:59:20 UTC 2017)

HW Platform:
  Generic DRA74X (Flattened Device Tree)
  DRA75X ES2.0 GP Device (STANDARD performance (1.0GHz))
  TPS659038  ES2.2

SW Build Details:
  Build:
    Version: Debian GNU/Linux 8
  Kernel:
    Version: 4.4.41-rt50-g968d071ce9
    Author: devel@debian
    Toolchain: gcc version 4.9.4 (Linaro GCC 4.9-2017.01)
    Type: #12 SMP PREEMPT RT
    Date: Wed Jun 7 16:47:59 CEST 2017

51

So actually this is also a way to get the temperature without the sysfs.. Anyhow is it possible to surpress the HW Platform and SW Build Details? So I just get 51 as an answer without parsing the output with another command?

Regards Guy