Hi Jean, > It is expected due to the hardware implementation. The lowest speed that > can be monitored (and thus the lowest limit you can set) depends on an > internal clock speed and a clock divider. For a divider of 8, this is > (32768*60)/(2*8*192) = 640. For lower dividers, the value is even > greater. Thanks for good explaining. > > smsc47m1-isa-0800 > > Adapter: ISA adapter > > fan1: 0 RPM (min = 640 RPM, div = 8) ALARM > > fan2: 1050 RPM (min = 1280 RPM, div = 4) ALARM > > This is more surprising, as the driver should try to preserve the low > limit on divider increment. Unless you actually did it the other way > around (4 then 1)? I took a look at the code and it looks correct to me. > > Anyway, you can set the value again by writing it to fan2_min. Other experiment: ----- [root at home 1-0800]# echo 4 >fan2_div fan2: 1041 RPM (min = 1280 RPM, div = 4) ALARM [root at home 1-0800]# echo 1 >fan2_div fan2: 0 RPM (min = 5120 RPM, div = 1) ALARM [root at home 1-0800]# echo 4 >fan2_div fan2: 0 RPM (min = 5120 RPM, div = 4) ALARM [root at home 1-0800]# echo 8 >fan2_div fan2: 0 RPM (min = 5120 RPM, div = 8) ALARM [root at home 1-0800]# echo 640 >fan2_min fan2: 1059 RPM (min = 640 RPM, div = 8) ALARM ----- > > That's expected, as libsensors doesn't know about fan speed control > except for a few chips. Typically, PWM operations are done directly > through sysfs. Check in /sys/bus/i2c/devices, you should find a > directory for your chip and pwm files here. Use with caution, of course. Yes, it works perfectly! I can set values 1 to 252 for pwm. With echo 0 >pwm2_enable my secondary fan totally stops. There is some experiments: ------------- [root at home 1-0800]# pwd /sys/bus/i2c/devices/1-0800 [root at home 1-0800]# cat pwm2 144 [root at home 1-0800]# echo 10 >pwm2 fan2: 3072 RPM (min = 640 RPM, div = 8) [root at home 1-0800]# cat pwm2 8 [root at home 1-0800]# echo 128 >pwm2 fan2: 1307 RPM (min = 640 RPM, div = 8) [root at home 1-0800]# cat pwm2_enable 1 [root at home 1-0800]# echo 0 >pwm2_enable fan2: 0 RPM (min = 640 RPM, div = 8) ALARM [root at home 1-0800]# echo 1 >pwm2_enable fan2: 1307 RPM (min = 640 RPM, div = 8) -------------- > Anyway, the tests above are sufficient to convince me that your chip is > compatible with the LPC47M192 as fan as fan control and monitoring is > concerned. We will have to update our documentation accordingly. Thank you very much. Best regards, Pavel Ruzicka
