On Monday 30 May 2016 17:26:36 Gabriele Mazzotta wrote: > On 30/05/2016 11:32, Pali Rohár wrote: > > On Friday 27 May 2016 14:11:11 Gabriele Mazzotta wrote: > >> On 22/05/2016 13:50, Pali Rohár wrote: > >>> This patch exports standard hwmon pwmX_enable sysfs attribute for enabling > >>> or disabling automatic fan control by BIOS. Standard value "1" is for > >>> disabling automatic BIOS fan control and value "2" for enabling. > >>> > >>> Currently there is no way to check if BIOS auto mode is enabled (at least > >>> it is not know how to do it), so hwmon sysfs attribute is write-only. > >>> > >>> By default BIOS auto mode is enabled by laptop firmware. > >>> > >>> When BIOS auto mode is enabled, custom fan speed value (set via hwmon pwmX > >>> sysfs attribute) is overwritten by SMM in few seconds and therefore any > >>> custom settings are without effect. So this is reason why implementing > >>> option for disabling BIOS auto mode is needed. > >>> > >>> So finally this patch allows kernel to set and control fan speed on > >>> laptops, but it can be dangerous (like setting speed of other fans). > >>> > >>> This new feature is highly experimental, uses Dell SMM calls, so does not > >>> have to be supported by all laptops BIOSes. It was tested on Dell Latitude > >>> E6440 with BIOS A5. > >> > >> Tested on a Dell XPS13 9333. Changing the value of pwm1_enable appears > >> to have no effect here. > > > > Can you check what i8k_enable_fan_auto_mode() returns? Error code or not? > > No error. However, independently on the value I set, the BIOS always > overrides the speed of the fan. Ok, looks like this is model or platform specific call... If you want, you can try to play with dellfan source code [1]. There is e.g. in comment specified two methods for disabling that BIOS thermal automode [2]. Looks like second method is that which I implemented in patch... [1] - https://github.com/clopez/dellfan [2] - https://github.com/clopez/dellfan/blob/master/dellfan.c#L64 -- Pali Rohár pali.rohar@xxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-hwmon" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
