[ltp] possible fan firmware bug after WLAN was active on X61s

[Thomas Kahle]

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|> I experienced the same problem, it is described a bit at
|> http://pi-ist-genau-3.de/?page_id=344.
|> My conclusion was, that the sensor which measures the temperature at the
|> wlan-card is used to compute the fan speed, while the fan, located in
|> the top left of the mainboard, does not cool the wlan at all, so this is
|> just of stupid.
|
| The fan stayed on even after I disabled the WLAN. Furthermore, sensors
| shows low temperatures, and the fan goes off after the ThinkPads was
| suspended, even if it was suspended for just 1 second. So I suppose
| that it is just weired firmware.

You should check the version history of the BIOS, at some point they
also made changes at the fan-control. Maybe a Bios upgrade helps.
I heard some rumors that the list of changes for new Bios versions is
not complete, so maybe they also changed something with the fan in newer
versions.

|> - -) Use fan control scripts to change the threshshold of the temperature
|> at the wlan-card. You find them on the thinkwiki.
|
| This has the potential to damage the hardware, therefore I don't use
| such things with a > 1000 EUR laptop.

What convinced me was the availability of the "watchdog", as soon as the
script does not set the fan-levels for 5 seconds, say, the BIOS retakes
control.

Furthermore I extensively monitored the temperatures and the
miniPCI(wlan)-temperature is THE SAME with the script on or BIOS
control. (Since the fan does not cool the miniPCI). For all other
sensors I left the threshholds at conservative values that are easily
reached with BIOS control too.

For this two reasons I decided it is safe enough for me.


best
Thomas
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