term_adt746x: Invert bit required on this Powerbook G4

[Max Vozeler]

On Wed, Nov 04, 2009 at 01:23:55PM +0100, Max Vozeler wrote:
> After some poking around, in which everything seemed to be
> according to plan including write of 0 to both FAN_SPD_SET regs,
> I noticed that explicitly *setting* the invert bit as in 
> 
>  -		write_reg(th, MANUAL_MODE[fan],
>  -			(manual|MANUAL_MASK) & (~INVERT_MASK));
>  +		write_reg(th, MANUAL_MODE[fan],
>  +			(manual|MANUAL_MASK|INVERT_MASK));
> 
> seems to cure it. The fan appears to behave normally now, it
> turns on slowly when the temp limits are reached, otherwise it
> stays off. The temperature is reasonable (ie, no too hot).
> 
> So, puzzeled, I checked the spec, and it appears very clear on
> the question of invert: It should be off by default.

Another datapoint: 

The PRAM battery in this Powerbook is old, so it forgets e.g.
clock state completely when not connected to the power supply.

These are the PWM1/PWM2 registers during probe_thermostat() 
after such a complete poweroff:

[   28.332700] adt746x: ADT7460 initializing
[   28.385266] ZZZ MANUAL_MODE[0] 0xd2
[   28.385832] ZZZ MANUAL_MODE[1] 0x82

So if I'm reading this correctly, PWM1 starts off with the 
invert bit (0x10) set, for some reason.

	Max