Bogus value sometimes returned by /sys/class/thermal/thermal_zone0/temp

[MilhouseVH]

When reading /sys/class/thermal/thermal_zone0/temp, very occasionally a bogus value (large, negative value such as -650788984, or alternatively 85000 when the real temp is much less) will be returned. Re-reading the temperature will usually return a sane value.

See issue #132 for additional background and discussion.

[popcornmix]

BTW are you still seeing this?
I've just had a look and after 120k reads, all are in 50000->60000 range.

[MilhouseVH]

I'm pretty sure I haven't seen any large negative value in quite some time, so that's probably no longer an issue, however I've been ignoring values of 85000 and above so I can't be so sure about that.

I'll run some checks to see if 85000 (or large negative) still pops up from time to time, give me a few days and I'll let you know.

[popcornmix]

I've not knowingly fixed it, so it's probably still there, but
while : ; do cat /sys/class/thermal/thermal_zone0/temp >> templog ; done &
has been running about an hour - now 165k entries, but
grep -v ^5 templog
is showing nothing.

[MilhouseVH]

I left 5 processes running overnight (~12 hours), each on a Raspbian-based Pi (3.10.36+ #664) and an OpenELEC-based Pi (3.14.0), 10 processes total, each process reading continuously from /sys/class/thermal/thermal_zone0/temp.

Each Pi clocked up over 6 million reads, and after over 12 million combined reads I've seen no out-of-range values (no big negative or >= 85000) so I think this can now be closed - if it ever crops up again I guess it can be reopened.