[PATCH] powermac: thermal control turns system off in normal temperature conditions

[Linux User #330250]

Hello!

First: I'm just a user. And I hope I don't cause disturbance.

I've read about this when I was setting up Linux on my Power Mac G4 MDD about 
two years ago and I remember reading that the temperature might be reported 
falsely. The original author reduced the limits to be on the safe side.

While Mac OS X seems to push the allowed temperature more to the limits, it 
could still be fatal to trust the reported temperatures.


My machine had the same shut-downs due to temperature at first. Since my MDD 
was quite a few years old when I got it I cleaned the CPUs and used new 
thermal compound with the original heatsink. This fixed the "overheat" issue 
for me.


Sorry to interrupt,
Andreas  aka  Linux User #330250



----------  Original message  ----------
Subject: [PATCH] powermac: thermal control turns system off in normal 
temperature conditions
Date:    Sonntag, 30. August 2009N
From:    Bartlomiej Zolnierkiewicz <bzolnier at gmail.com>
To:      Benjamin Herrenschmidt <benh at kernel.crashing.org>

> From: Lyonel Vincent <lyonel at ezix.org>
> Subject: [PATCH] powermac: thermal control turns system off in normal
> temperature conditions
>
> On certain PowerMacs, a module (therm_windtunnel) controls various
> thermal settings (it can report CPU/case temperature, change speed
> of internal fans, etc.)
>
> By default, the hardware thermal control has a temperature limit to
> protect the computer from damages (the default limit seems to be 80°C)
> but therm_windtunnel.c reduces it to an anormaly low value (65°C),
> which means that he computer will shut down randomly when hit by direct
> sun light or during summer (summer in France can be quite hot), actually
> possibly losing data instead of protecting it.
>
> The overheat limit in therm_windtunnel.c:253-254 should be set to 75°C
> and 70°C instead of 65°C and 60°C respectively.
>
> From: Lyonel Vincent <lyonel at ezix.org>
> Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier at gmail.com>
> ---
> Resurrected from Fedora's bugzilla (aka The Big Black Hole):
> https://bugzilla.redhat.com/show_bug.cgi?id=171937
>
> The patch itself seems perfectly valid to me
> (especially given comments in therm_windtunnel.c).
>
>  drivers/macintosh/therm_windtunnel.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> Index: b/drivers/macintosh/therm_windtunnel.c
> ===================================================================
> --- a/drivers/macintosh/therm_windtunnel.c
> +++ b/drivers/macintosh/therm_windtunnel.c
> @@ -239,8 +239,8 @@ setup_hardware( void )
>  	 * to be on the safe side (OSX doesn't)...
>  	 */
>  	if( x.overheat_temp == (80 << 8) ) {
> -		x.overheat_temp = 65 << 8;
> -		x.overheat_hyst = 60 << 8;
> +		x.overheat_temp = 75 << 8;
> +		x.overheat_hyst = 70 << 8;
>  		write_reg( x.thermostat, 2, x.overheat_hyst, 2 );
>  		write_reg( x.thermostat, 3, x.overheat_temp, 2 );