Issue with upstream BCM2835 thermal and hwmon.

[Stefan Wahren]

Hi Michael,

> Michael Tatarinov <kukabu at gmail.com> hat am 7. Juli 2017 um 13:59 geschrieben:
> 
> 
> 2017-07-07 15:32 GMT+04:00, Stefan Wahren <stefan.wahren at i2se.com>:
> > Hi Michael,
> >
> > Am 07.07.2017 um 13:02 schrieb Michael Tatarinov:
> >> Hello
> >>
> >> I uses custom kernel based on downstream code (branch rpi-4.12.y now).
> >> My kernel builds with
> >> CONFIG_HWMON=y
> >> CONFIG_THERMAL=y
> >> CONFIG_THERMAL_HWMON=y
> >> The downstream thermal driver is registered in hwmon subsystem as
> >> virtual device but the upstream isn't.
> >> I'm not sure that the problem is in the upstream driver, maybe this is
> >> my issue.
> >> Does anybody can check it with upstream kernel?
> >
> > i didn't know about the relation between hwmon and thermal.
> 
> The thermal subsystem have helper for hwmon.
> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/thermal/Kconfig#n35
> 
> > Could you please do me a favor and do the following steps:
> > 1. Check with your upstream kernel that the thermal_zone is successfully
> > registered under /sys/class/thermal.
> 
> Yes, /sys/class/thermal is exists and I see the current data.
> 
> > 2. Please show me the (missing) hwmon sysfs entries on your downstream
> > kernel, because i won't trust some userspace program like sensors.
> 
> mike at rpi ~ $ head /sys/class/hwmon/hwmon0/{name,temp1_input}
> ==> /sys/class/hwmon/hwmon0/name <==
> bcm2835_thermal
> 
> ==> /sys/class/hwmon/hwmon0/temp1_input <==
> 59451
> mike at rpi ~ $

thanks. I can reproduce it with my Raspberry Pi Zero W. But this behavior is desired and not an issue (since the driver has thermal_zone_params):

https://github.com/torvalds/linux/commit/ccba4ffd9eff6120a20cc7656458ac554aec4b0c

Please ask the thermal guys for a better explanation. Sorry

> 
> > Best regards
> > Stefan