> > >> 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, I played around with your patch a bit on my Vostro V131 (BIOS A04) and the results are similar to Gabriele's: * I can write values 1 and 2 to pwm{1,2}_enable, which causes i8k_enable_fan_auto_mode() to return 0, but the desired speed set using pwm{1,2} is quickly overridden by the BIOS, no matter which thermal control mode is set, * trying to set the BIOS thermal control mode to the same value it was already set to causes i8k_enable_fan_auto_mode() to return -22: # echo 1 > /sys/class/hwmon/hwmon1/pwm1_enable # echo 1 > /sys/class/hwmon/hwmon1/pwm1_enable bash: echo: write error: Input/output error # echo 2 > /sys/class/hwmon/hwmon1/pwm2_enable # echo 2 > /sys/class/hwmon/hwmon1/pwm2_enable bash: echo: write error: Input/output error # echo 1 > /sys/class/hwmon/hwmon1/pwm1_enable # echo 2 > /sys/class/hwmon/hwmon1/pwm2_enable # * I tried changing I8K_SMM_MANUAL_FAN and I8K_SMM_AUTO_FAN to 0x30a3 and 0x31a3, respectively (according to [2]), but it hasn't changed anything, i.e. BIOS is taking over shortly after any value is written to pwm{1,2}. -- Best regards, Michał Kępień -- 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