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HP nx6125: ACPI thermal events (or lack thereof)


I know that this is more of a laptop issue than a 64bit one per se. However, I 
posted the message below to debian-laptop and got no replies. I am hoping 
that there is someone on this list with a similar 64bit laptop (HP nx6125) 
who may be able to verify the strange behaviour described below, or at least 
point me in the right direction as to why my thermal events are only getting 
processed when I do a

cat /proc/acpi/thermal_zone/TZ?/temperature

or an

acpi -t

(I thought that this might be a latency issue and have since re-compiled with 
option 3 --preemptable kernel-- with no change in the behaviour mentioned 

Many thanks if someone can shed some light on this and sorry for the long 
post, but I thought it best to give all the facts.


----------  Forwarded Message  ----------

I've been working steadily over the past few weeks to get my new HP nx6125
working under Debian (amd64 port) and have made significant progress.
However, there is one considerable problem: thermal events don't seem to be
recognised or processed by the kernel (until I do a
cat /proc/acpi/thermal_zone/TZ?/temperature). As soon as I do anything CPU
intensive I really run the risk of frying my laptop :-(

To be more specific, I am running kernel
(www.kernel.org vanilla) with the double timer patch applied (see
http://bugzilla.kernel.org/attachment.cgi?id=6061&action=view). When I boot
up, my thermal trip points get set nicely. The first is at 58 *C, then 65*C,
then 75 *C, and 80*C (S5 = 95 *C). When I was testing things I was doing
frequent executions of

cat /proc/acpi/thermal_zone/TZ?/temperature

and I would observe the temp rise to 58 C, then the fan would kick in, the
first trip point would then (automatically) re-set to 50 C and the CPU would
cool through 8 C before the fan turned off (nice, I thought, and very clever
this re-setting of trip points--sorry I'm very new to ACPI). When the fan
turned off, the trip point would again re-set to 58 C. So, I thought all was
working well. However, subsequent tests done by running glxgears and not
executing the above cat command allowed the CPU temp to rise above several
trip points without the fans kicking in! Only when I ran the above cat
command did the fans start!?

So, I stopped acpid and did a

cat /proc/acpi/event

while running glxgears. I waited a while and then did a
cat  /proc/acpi/thermal_zone/TZ?/temperature to see that indeed the temp of
TZ1 had exceeded 58C---and immediately /proc/acpi/event received a thermal
event (note: the temp had already exceeded 58 C, my first thermal trip point;
the thermal event only occurred when I did the 'cat'). So, in order for
thermal events to "get through/processed" I need to keep doing
cat  /proc/acpi/thermal_zone/TZ?/temperature!!!!

Can anybody shed some light on this behaviour. I don't know much about ACPI,
but it seems (?) like the linux kernel is not processing the thermal events
properly. Incidentally, I am also seeing spurious syslog errors that read
APIC error on CPU0: 40(40) meaning that some interrupts presumably are not
being correctly identified by the interrupt controller (thermal ones? could
there be some correlation here?).

Other info: the HP nx6125 is a Turion 64 based laptop with ATI chipset (yes,
 I know). I am running acpid and have just installed powernowd (doesn't fix
 it). I have also observed the above behaviour running the standard Debian
 2.6.12-1-amd64 kernel (booting with no_timer_check to avoid double timer
 interrupts).  Any help, suggestions would be greatly appreciated.  If anyone
 has any ideas why catting  /proc/acpi/thermal_zone/TZ?/temperature gets
 things to work, I'd be very happy to hear an explanation, too.


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