[ltp] Re: tpfand configuration for an X200s

[Henrique de Moraes Holschuh]

On Wed, 03 Dec 2008, John Li wrote:
> Can you say how likely would this be? Since under Linux, the system
> does seem to consistently draw /at least/ ~2.5W more, maybe the fan
> "issue" is really just a heat generation/dissipation issue.

Well, if something is not perfect in the assembly of your thinkpad, it is
quite likely.  ThinkPads have an history of half-assed jobs done both in the
factory and on repair shops when attaching the cooling systems to the GPU,
CPU, etc.

> How should we go about contacting Lenovo about these issues?

If Linux is drawing 2.5W more?  There is nothing that can be done about it
through Lenovo, we will have to figure it out ourselves.

> Aside from threshholds and heat generation, though, I think there's
> still a bug somewhere: after the fan speeds up, even when temperatures
> become lower (lower than when the fan was at ~1900), the fan still
> spins at ~3500. Kernel issue? thinkpad-acpi issue? The problem doesn't
> happen in Vista, so I wouldn't think it'd be a hardware/EC/BIOS issue.

Well, the EC controls the fan speed.  ACPI doesn't, and Vista is extremely
unlikely to be doing it (Lenovo would just adjust the EC control program
accordingly, instead).

thinkpad-acpi really is not part of the problem if you leave the fan in AUTO
mode.

BTW: You can ask Lenovo to reduce the ammount of hysteresis in the fan
control loop.  That would make the fan slow down sooner.

> Or is the fan speed determined by something other than the numbers we
> can see with thinkpad-acpi's thermal readings?

Yes, the EC might be taking into account extra factors than the thermal
sensors we know about.

If you could test the vista behaviour with the thermal sensors at the same
level as in Linux, and you find out that the EC behaves differently for the
same set of temperatures in the sensors, than that would prove there is
something else affecting the EC decision about the fan speed.

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh