initial value of tz_active

[Nate Lawson]

Andriy Gapon wrote:
> It seems that tz_active (in acpi_thermal) is initialized to NONE/-1.
> I don't have a patch, but I have an idea - acpi_thermal should query
> current power state of fans and set tz_active based on that.
> For example, some systems start up with all fans turned on (at full
> speed) for safety reasons, acpi_thermal sees that temperature is low
> enough, it thinks/assumes that no fan is active, so it doesn't change AC
> level, so in reality AC0 is always in effect.

Good point.  I think there should be a "first_time" static that is set 
on boot.  Once acpi_thermal decides to turn some fans on or off, 
first_time is set.  Until it has been set, all fan control is actually 
performed, regardless of tz_active.  After it is set, we can depend on 
tz_active as before.

The reason we can't just read the fan status and initialize tz_active 
accordingly is that some ASL doesn't return the real value of the fans. 
  It just returns a hard-coded value.  On many systems, it does return 
the real value but if even one system is wrong, we can't trust any of them.

-- 
Nate