Bug 200949

Summary:	dell_smm_hwmon fan constantly blows
Product:	Platform Specific/Hardware	Reporter:	Dominik (dklonowski87)
Component:	x86-64	Assignee:	platform_x86_64 (platform_x86_64)
Status:	NEW ---
Severity:	normal	CC:	gio, yvan
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	4.17.0-3	Subsystem:
Regression:	No	Bisected commit-id:

Description Dominik 2018-08-27 13:30:49 UTC

Machine: Dell Latitude x5530 vPro 01
Distro: regardless, but currently Debian buster (testing)

I find behavior of machine with loaded dell_smm_hwmon strange.
once fan turns on due to heat, it stops very late. 
according to sensors 
dell_smm-virtual-0
Adapter: Virtual device
Processor Fan: 3202 RPM
CPU:            +39.0°C
Ambient:        +42.0°C
SODIMM:         +41.0°C

while after circa 5mins of constant fan noise

dell_smm-virtual-0
Adapter: Virtual device
Processor Fan:    0 RPM
CPU:            +40.0°C
Ambient:        +42.0°C
SODIMM:         +40.0°C



Temperature can drop as low as 35 degs and fan will happily break nights' calm.
Moreover, dedicated program i8[mon|fan|ctl] ignores my forcing of turning cooler down

root@phoebe:~# i8kctl fan 0 0
-1 1

It looks for me like hardware is still controlled on lower lever (bios?). These manufacturer's rules are unacceptable for me; OpenIndiana does not have any helpers to interact with fan so while using this OS i am forced to suffer because of this near random behaviour.

I didn't checked cooler behaviour under Windows, as i replaced OS right after reaching home with new laptop :)

Comment 1 Giovanni Mascellani 2019-02-14 12:49:44 UTC

I have the same problem (on a Dell Precision 5530, with Debian unstable). It appears that the problem is related to the BIOS not actually giving up on directly controlling the fan speed. An undocumented call to disable the BIOS control of the fans was discovered and is available here:

 https://github.com/clopez/dellfan

It would probably be nice to integrate this call in the dell-smm-hwmon module.