id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc
2356,"it87 in 2.6.27: no fan divisors, fan speeds are wrong",ticket,khali,"Just updated my system to 2.6.27, and the first thing I noticed is that sensors now shows wrong fan speeds, as it was the (fixed) case before.

It's an Asus M3A78-EM motherboard (AMD 780G/SB700 chipset), with ""IT8712F chip at 0x290, revision 8"" sensor (from dmesg).
On 2.6.26 and before, I used to set fan*_div to higher value (not the default of 2), or else fan speeds were way off.  My only fan in the PSU is usually rotating at 400..800RPM, and it is connected to the CPU Fan connector, with which it was possible to set fan1_div to 16 or even 32, not to 8 max as with PSU Fan connector (which were not sufficient to get correct speeds).  Now, as there's no fan_div anymore, it again shows incorrect fan speed.  Right now:

{{{
it8712-isa-0290
Adapter: ISA adapter
VCore 1:     +0.99 V  (min =  +4.02 V, max =  +4.08 V)   ALARM
VCore 2:     +3.68 V  (min =  +4.05 V, max =  +4.08 V)   ALARM
+3.3V:       +3.33 V  (min =  +4.02 V, max =  +4.05 V)   ALARM
+5V:         +5.13 V  (min =  +5.99 V, max =  +6.85 V)   ALARM
+12V:       +12.74 V  (min =  +0.00 V, max = +16.32 V)   
-12V:       -15.46 V  (min =  +3.81 V, max =  +3.93 V)   ALARM
-5V:         +4.03 V  (min =  +3.96 V, max =  +4.03 V)   ALARM
Stdby:       +6.42 V  (min =  +0.00 V, max =  +6.83 V)   
VBat:        +3.28 V
PSU Fan:    4753 RPM  (min =  399 RPM)
CPU Temp:    +38.0°C  (low  = +65.0°C, high = +70.0°C)  sensor = transistor
M/B Temp:    +41.0°C  (low  = +60.0°C, high = +65.0°C)  sensor = transistor
cpu0_vid:   +1.550 V
}}}

(don't ask about voltages - did not get there yet, all I need are the fans and the temps).

I don't remember if the value reported was the same as with 2.6.26 without fan_div tweaks.  The thing is that it obviously changes since fan speed follows temperature, and is controlled by the circuit in the PSU.  What I remember for sure is that *after* upping fan_div on 2.6.26, the value more-or-less matched the same value as reported by bios (esp. when a fan is attached to non-regulated connector or when q-fan feature is turned off).

I've seen the diff between 2.6.26 and 2.6.27, and understand my sensor *should* work out of the box.  But it doesn't.  It looks like the divisor should be somewhere in the driver instead, or the driver is reading the wrong value.

By the way, very similar effects were observed on many other Asus motherboards with it8712 chips.

Thanks!",defect,closed,major,,kernel,kernel,fixed,it87 fan_speed,mjt+lmsensors@…