[lm-sensors] RFC: nct6776f support in the w83627ehf and fan RPMsignal de-bounce

[Guenter Roeck]

Hi Robert,

On Thu, Mar 10, 2011 at 03:05:04PM -0500, Robert Kaiser wrote:
> Guenter Roeck schrieb:
> > On Thu, Mar 10, 2011 at 06:53:28AM -0500, Guenter Roeck wrote:
> > [ ... ]
> >>>
> >>> So first question is what chip he has.
> >>>
> >> ... answer is NCT6775F, from Robert's log. It uses the "old" registers for the min
> >> speed settings, so presumably that should be correct. Yet, there must be a reason
> >> for the alarm. Maybe it is the "maximum RPM" register after all - the NCT6775F
> >> has that set of registers as well.
> >>
> > Doesn't look like the "maximum RPM" register is the culprit. I have a system with NCT6775F
> > (not using its fan controls, though). Looks like one can not write into that register, so it
> > must be a status register. Maybe it reports the maximum RPM the chip has seen.
> 
> OK, so here's a bit of shortened output of my tests:
> 
> 
> # echo 5000 > /sys/devices/platform/w83627ehf.656/fan2_min
> # sensors
> [...]
> fan2:                    0 RPM  (min = 5037 RPM, div = 4)
> [...]
> 
> # sensors
> [...]
> fan2:                 1102 RPM  (min = 5113 RPM, div = 8)  ALARM
> [...]
> 
> # sensors
> [...]
> fan2:                 1095 RPM  (min = 5113 RPM, div = 8)  ALARM
> [...]
> 
> # sensors
> [...]
> fan2:                 1061 RPM  (min = 5113 RPM, div = 8)  ALARM
> [...]
> 
> # echo 0 > /sys/devices/platform/w83627ehf.656/fan2_min
> # sensors
> [...]
> fan2:                 1054 RPM  (min =    0 RPM, div = 8)
> [...]
> 
> # sensors
> [...]
> fan2:                 1095 RPM  (min =    0 RPM, div = 8)
> [...]
> 
> # sensors
> [...]
> fan2:                 1061 RPM  (min =    0 RPM, div = 8)
> [...]
> 
> 
> So, in short, it looks like it's correct that this is a minimum, but it 
> might get triggered very early in the cycle or so and when re-setting 
> the alarm due to that re-writing of the minimum, everything is OK.
> 
Looks like it.

Thanks a lot for the testing!

Guenter