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

From: Bartlomiej Zolnierkiewicz
Date: Sun Aug 30 2009 - 14:59:26 EST

From: Lyonel Vincent <lyonel@xxxxxxxx>
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@xxxxxxxx>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx>
Resurrected from Fedora's bugzilla (aka The Big Black Hole):

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 );

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