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. -- 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
