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-   -   mdk 9.1, ACPI, fan speed problem (https://www.linuxquestions.org/questions/linux-laptop-and-netbook-25/mdk-9-1-acpi-fan-speed-problem-101667/)

tactor 10-08-2003 12:02 PM

mdk 9.1, ACPI, fan speed problem
 
Hi, I'm running Mandrake Linux 9.1 on a laptop (Comex, an italian brand). In order to let power management control work, I had to recompile the kernel (2.4.21-0.25mdk) and now everything is controlled by ACPI.
It works fine, because the system shuts down automatically, with no need to press the button and the battery indicator shows the right values.
I only have a little problem with the fan: looks like the systems starts to control the fan speed only if the CPU has reached a certain temperature, before that the fan goes at full speed. In fact, if I use 100% of the CPU for a while and it gets hot enough, the fan slows down, and then starts to work correctly, increasing and decreasing the speed at need, without going at full speed uselessy anymore.
Can anybody explain me why this happens and if there's a way to tell the system to manage the fan speed since boot?

These are the /var/log/messages lines that concern ACPI:

kernel: ACPI: RSDP (v000 PTLTD ) @ 0x000f6b30
kernel: ACPI: RSDT (v001 PTLTD RSDT 01540.00000) @ 0x0defa08c
kernel: ACPI: FADT (v001 SiS 645 01540.00000) @ 0x0defef64
kernel: ACPI: BOOT (v001 PTLTD $SBFTBL$ 01540.00000) @ 0x0defefd8
kernel: ACPI: DSDT (v001 PTLTD 635 01540.00000) @ 0x00000000
kernel: ACPI: BIOS passes blacklist
kernel: ACPI: Subsystem revision 20030122
kernel: ACPI: Interpreter enabled
kernel: ACPI: Using PIC for interrupt routing
kernel: ACPI: System [ACPI] (supports S0 S1 S4 S5)
kernel: ACPI: PCI Root Bridge [PCI0] (00:00)
kernel: ACPI: PCI Interrupt Link [LNKA] (IRQs *9 10)
kernel: ACPI: PCI Interrupt Link [LNKB] (IRQs *10)
kernel: ACPI: PCI Interrupt Link [LNKC] (IRQs *5)
kernel: ACPI: PCI Interrupt Link [LNKD] (IRQs *5)
kernel: ACPI: Power Resource [PFAN] (off)
kernel: ACPI: AC Adapter [ACAD] (on-line)
kernel: ACPI: Battery Slot [BAT0] (battery present)
kernel: ACPI: Power Button (FF) [PWRF]
kernel: ACPI: Lid Switch [LID]
kernel: ACPI: Fan [FAN] (on)
kernel: ACPI: Processor [CPU0] (supports C1, 4 throttling states)
kernel: ACPI: Thermal Zone [THRM] (26 C)

Thanks in anticipation.
Bye!
Enrico

lupin_the_3rd 10-08-2003 01:18 PM

do a cat /proc/acpi/fan ...use tab completion to see if there are any files that will give you some insight... example,

cat /proc/acpi/fan/state

tactor 10-09-2003 09:17 AM

cat /proc/acpi/fan/FAN/state
status: on

nothing else... it's the only file I found there.

tactor 10-09-2003 12:36 PM

I've discovered that the system starts to manage the fan speed when the CPU reaches the temperature of 45 C.
That temperature is set in the /proc/acpi/thermal_zone/THRM/trip_points file.
If I could set a lower temperature, probably the system would manage the fan speed since boot, but I can't edit that file, because I'm not allowed to save it, even if I'm root...

Thanks Lupin, because you told me where to look.

lupin_the_3rd 10-09-2003 12:50 PM

You should check out /etc/acpi b/c you can't edit the /proc filesystem.

You may be able to define your temperature there under "actions" or "events".... though, I think it's ok for the fan to not always be on if that's what you're saying... my acpi is set up to keep the cpu around 49C... fan speeds vary depending on amount of cpu usage. It doesn't come on until several minutes after boot... and the acpi events keep it from coming on high powered when on battery power.

See if this site helps any... it is for RH 9 but the acpi section is distro independent:

http://ltswww.epfl.ch/~dsanta/resour...ll-i8500-linux

the acpi events work well for me!


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