initial value of tz_active

[Andriy Gapon]

on 23/04/2008 22:46 Nate Lawson said the following:
> 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.
> 

I agree - this is a better approach.
On a technical level  - maybe use TZ_ACTIVE_UNKNOWN=-2 instead of a new
variable.
I'll try to work on this somewhere in the middle of May.

-- 
Andriy Gapon