Manually setting fan speed apart from cpufreq governor?

TerranAce007 · Apprentice Joined: 13 Dec 2004 Posts: 281 Location: Texas

Since I have a high end laptop, it tends to get warm. The fans don't always want to spin at full speed because they are supposed to save power by only speeding up when the system needs more cooling, but when I am on A/C power, this doesn't matter. I usually run the ondemand governer on AC power to keep the system cool and the cpu running slow when its idle, but that slows the fans down too. Is there a way to set the fans to full speed when on A/C, or to modify the ondemand governer that comes with the kernel to do this?
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alkan · Posted: Tue Mar 15, 2005 3:43 am Post subject:

If your laptop has an I2C hardware sensors interface, You can modprobe i2c modules depending on your hardware sensors chip. Then an interface will appear under /sys/bus/i2c/.... You can manually set the fan speed form there. In my case for a full fan speed, I do

TerranAce007 · Apprentice Joined: 13 Dec 2004 Posts: 281 Location: Texas

Well I have run sensors-detect with lm_sensors, however it doesn't detect anything. I have an SiS 755 mainboard, and so far it looks like SiS sensor support is almost noexistant in lm_sensors, probably due to SiS not supporting linux. I am hoping I can set the fan speed some other way, if the chipset allows the OS to do that. It is probably going to be hard-wired though. I have emailed the manufacturer and am still waiting for a response...
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bollucks · l33t Joined: 27 Oct 2004 Posts: 606

Benson · Posted: Tue Mar 15, 2005 12:38 pm Post subject:

If you have lm_sensors installed and configured, and you can read with it the rpm of the fan and the cpu-temp, try fancontrol, it's part of lm_sensors. You first have to run pwmconfigto configure it. It may work or not, depending on which chip your mainboard uses to read the temperature / fan-spedd infos...

rdgs
Benson

alkan · Posted: Tue Mar 15, 2005 4:56 pm Post subject:

If nothing works for you, there is another way. You first need to find the IO chip model-number/manufacturer that controls the fan (Look at SIS MB specs). Then go to their web page and download the manual for that chip. In the manual, find the IO port numbers and how to use the IO ports to set the fan speed. Then, have a look at 'ioport --help'. For example, my computers has a Winbond 83627hf IO chip, I can set the fan speeds by using 0x295-6 IO ports.

Benson · Posted: Sat Mar 19, 2005 12:29 pm Post subject:

ikaro · Advocate Joined: 14 Jul 2003 Posts: 2527 Location: Denmark

Thanks for the tip.

I got a zalman cpu cooler with a button/switch that allows me to control the speed of the fans, however
I have to reach to the computer case everytime I wanted to do so.

this makes things more simple.

Ive added a little menu to my fvwm config to adjust the speeds from the menu:

alkan · Posted: Sat Mar 19, 2005 6:11 pm Post subject:

It may not be possible for some MBs and for some fans if the fan control is hard coded into hardware (or there is no fan control capability at all). I bet most of the new MBs have some way controlling the fan speeds by software.

The best you can do (if nothing else is working for you) is to get more info about your MB and the name/model-number of the chipset. The fans are usually connected to the IO chips with power managment capabilities. And those chips usually have i2c or smbus interface to communicate with. In their manual, it is explained how to control the hardware that is connected to the IO chip using IO port ranges. Using the direct IO writing and reading, I was able to adjust the fan speeds for all the computers I owned both in windows and linux eventhought other softwares and ACPI system failed to do so. Good luck.

rmh3093 · Posted: Sat Mar 19, 2005 8:00 pm Post subject:

if you cant change your fan speed you could at least change the critcal temp of the cpu to a low value which would turn the fan on high instead of low
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TerranAce007 · Apprentice Joined: 13 Dec 2004 Posts: 281 Location: Texas

Well I tried that already, and theres no kind of cpu temp alarm setting in the BIOS. I have found an updated BIOS, but the changelog just adds support for the high end amd processors like 3700+. I have talked to some other people with similar laptops and they said the new BIOS does't add anything worthwhile.
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It's all funny until someone gets hurt.

Then it's hilarious.

rmh3093 · Posted: Sun Mar 20, 2005 2:16 am Post subject:

im not talking about the bios, with the i2c bus even if you cant get a fan speed you should be able to get a mobo and cpu temp reading and should be able to set the critical temp
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Do not meddle in the affairs of wizards, for they are subtle and quick to anger.

Benson · Posted: Sun Mar 20, 2005 9:44 am Post subject:

Alkan, now i see what you mean. But to see which path you have to use to set the fan speed, you don't really have to check the mainboard manual. Symply have a look at /sys/bus/i2c/devices/ - there should be some other directories with the different chipsets, if any of these subdirs contains something like pwm1 or pwm2, you can echo them some values, just as ikaro has in his menu-script.

So in my case (Soltek SL-75FRNL-L Mainboard) it seems like i have a pwm1 and pwm2, but i can't controll the fans, i tried it with different fans so i think i'll get a front panel for my pc witch enables to control the fans too...

rgds
Benson

alkan · Posted: Sun Mar 20, 2005 6:57 pm Post subject:

Benson, yes that was my very first suggestion, look at my first post. But he doesn't get any interface under /sys/. If he did, /dev/i2c should have appeared.

TerranAce007, I assume you compiled all the available i2c sensor chipsets as a module in the kernel.

Edit: Benso, Sorry I didn't see your second part of the post. either your hardware sensor chip module is buggy or your fans are not connected to it. If your fans are connected to your chip, it is still possible to control your fans with direct IO eventhought lm_sensors can't. That's my point, lm_sensors modules doesn't work always because of the different hardware implementations. I've seen chips that doesn't work with lm_sensors but still can control the fan speeds.