Hi!
At least on my post-Feb 2005 12" powerbook the therm_adt746x module sometimes
showed a fairly strange behaviour - my fan was steadily spinning up and down
every other second. AFAIK this happens, if either the GPU- or the CPU sensor
show an elevated temperature, but not both of them.
The attached patch
- IMHO fixes this issue
- tries to do smoother speed-changes by considering the previous speed and
temperature too
- shows the correct sensor-location in case of a single fan too
- does not use the fan_speed-parameter anymore - it tries to keep the speed
appropriate for temperature relative to the limit, thus one can change the
fan-speed/noise by changing the limit. Still, it could easily be changed back
to the former use of this parameter.
Comments are appreciated,
Michael
PS.: I only modified the update_fans_speed-function, thus the patch, although
made for 2.6.13, should work for 2.6.12.x as well!
--- linux-2.6.13/drivers/macintosh/therm_adt746x.c 2005-08-29
01:41:01.000000000 +0200
+++ linux-2.6.12-rc6/drivers/macintosh/therm_adt746x.c 2005-08-31
22:47:20.000000000 +0200
@@ -282,28 +282,40 @@
int var = th->temps[i] - th->limits[i];
if (var > -1) {
- int step = (255 - fan_speed) / 7;
- int new_speed = 0;
-
- /* hysteresis : change fan speed only if variation is
- * more than two degrees */
- if (abs(var - th->last_var[fan_number]) < 2)
+ int step = 255 / 14;
+ int new_speed = var + th->last_var[i-1] + 2;
+
+
+ /* hysteresis : update last_var only if variation is
+ * more than one */
+ if (var > 0 && abs(var - th->last_var[fan_number]) < 2)
{
+ lastvar = var;
continue;
+ }
+
+
+ th->last_var[i-1] = (var + th->last_var[i-1])/2 + 1;
- started = 1;
- new_speed = fan_speed + ((var-1)*step);
-
- if (new_speed < fan_speed)
- new_speed = fan_speed;
+ if (i == 2 && fan_number == 0 && lastvar >= var)
+ continue;
+ lastvar = var;
+
+ new_speed = ( ( new_speed * step ) +
th->last_speed[fan_number] ) / 2;
+
+ if (new_speed < 0)
+ new_speed = 0;
if (new_speed > 255)
new_speed = 255;
+
+ if (new_speed == th->last_speed[fan_number])
+ continue;
+ started = 1;
printk(KERN_DEBUG "adt746x: setting fans speed to %d "
"(limit exceeded by %d on %s) \n",
new_speed, var,
- sensor_location[fan_number+1]);
+ sensor_location[i]);
write_both_fan_speed(th, new_speed);
- th->last_var[fan_number] = var;
} else if (var < -2) {
/* don't stop fan if sensor2 is cold and sensor1 is not
* so cold (lastvar >= -1) */
