Recent snapshots of OpenWrt seem to break the MT7623 CPU temperature monitoring in at least the BPI-R2 (my U7623 is in bits and not usable to test ATM).
I noticed first in LUCI that the CPU thermal page was locked at zero. This seems right from the sensor.
From 22.02.03:
Thanks, yes, I did look for other temps. It's the only one in the /sys tree.
In SNAPSHOT:
root@OpenWrt:/sys# ls -1 /sys/class/thermal/thermal_zone*/type | xargs -I % sh -c "echo % ; cat %"
/sys/class/thermal/thermal_zone0/type
cpu-thermal
root@OpenWrt:/sys# ls -1 /sys/class/thermal/thermal_zone*/temp | xargs -I % sh -c "echo % ; cat %"
/sys/class/thermal/thermal_zone0/temp
0
I did wonder if there were kernel mods that weren't being installed in snapshot, but I compared the kmods in release to snapshot and I don't see anything that jumps out at me.
Yes, I was involved in the early days of that (others ran with it when I had eye surgery). It's not to do with sensors, just the thermal CPU throttling. I looked at it, it's benign with respect to sensors (changes the trip point where CPU throttling occurs because MediaTek's original trip points were insane).
Well, the only guess I have left is that a kernel bump removed some patches which are now upstream included. Maybe for the bcm27xx target something got removed also and causing an error now? So other devices like Belkin RT3200 with mt based cpus are not affected.
EDIT: I got a bit confused and mixed up things. The Pro is Rockchip. While non-pro isn't.