thermal_zone4 reports 100 degree celcius ?

We are running TX1 under a room temperature and the fan is running at full speed with the original heat sink. However, I found out that zone4 is reporting a temperature near 100 deg Celsius, whereas all other zones are reporting temperature about 36 ~ 38c.

So I’m trying to find out, for each thermal zone 0-7, which cpu core does it associate to (checked the menu but could not find it), and why there is a huge difference on temperature between zone4 and other zones.

Thank you

Hi sjlin,

Sysfs node /sys/class/thermal/thermal_zone*/type can show the information.
Zone4 is for PMIC, that’s why its value is much different to other zones.

Hi Trumany:

Thank you for the reply.
So do you know why PMIC may reach 100c ? Because even on a new TX1, when no program is running, this zone still reports 100c.

If no program is running, after a while, TX1 will enter low power status and the current consumption should be very low, 100c is too high then. If so, there might be component shorted to GND.

Can you measure the system current to estimate the power through PMIC?

Sorry, I forgot to mention that, even running the TX1 with its original development board and power supply, I still see zone4 reports 100c. In fact, all 5 TX1s I have report the same thing when there are no program running.

Hi sjlin,

According to internal check info, thermal_zone4 is not the value read from PMIC but a value used by driver, it is fixed to 100C to illustrate the temp of PMIC is normal.

Haha, thank you so much, that makes a lot of sense.

Does this hold true for the TX2 as well?

Yes, but thermal zones ordering is a bit different on TX2, PMIC is zone7.