Can't give fan control back to the firmware

[Atemu]

After setting fan speed manually, there is no obvious way to give fan control back to the motherboard firmware; applying the firmware fan curves again. It'd be great if you could i.e. write -1 into the pwm device to do that.

[SergeyMy]

There is NO way to return, it seems like it should return when unloading the module, but alas, there is no way. in other drivers there is

pwm0_mode pwm0_enable

this needs to be completed here

[Fred78290]

Hi all, the main problem is to collect original settings, save it and restore it as needed.

In bios you can set different level for speed fan according temperature. Via the NCT6667 register you just say run the fan as this speed, so with fancontrol when you ask to save the state, it will be the instant state not the settings from bios.

I think that the temperature/fan speed according the temperature that you set in the bios is not handled by NCT itself but with another helper controller.

Having reading NCT 6683 technical book, I haven't see the feature fan speed/temperature control.

In the official kernel the feature to change fan speed is not available.

Help welcome.

[SergeyMy]

I just started looking yesterday... in kernel 6.5.8 :) for such (nct6775) drivers, the control mode is specified manually or automatically.... I'll continue searching :)

[SergeyMy]

Help welcome.

static void nct6687_restore_fan_control
{
.....
nct6687_write(data, NCT6687_REG_FAN_CTRL_MODE(0), 0);
} //end static void nct6687_restore_fan_control :):):)

but it’s better to create pwmX_enable as well :):)

FAN_CTRL_MODE 1 -man 0 -auto

[Fred78290]

Create another template group command allowing switch mode auto/manual for pwm

SENSOR_TEMPLATE(pwmode, "pwmmode%d", S_IRUGO, show_pw, switch_pwm, 0); Why not

[SergeyMy]

better by analogy with // adhere to the standard ;) Documentation/hwmon/nct6775.rst

sysfs attributes
----------------

pwm[1-7]
    - this file stores PWM duty cycle or DC value (fan speed) in range:

           0 (lowest speed) to 255 (full)

pwm[1-7]_enable
    - this file controls mode of fan/temperature control:

        * 0 Fan control disabled (fans set to maximum speed)
        * 1 Manual mode, write to pwm[0-5] any value 0-255
        * 2 "Thermal Cruise" mode
        * 3 "Fan Speed Cruise" mode
        * 4 "Smart Fan III" mode (NCT6775F only)
        * 5 "Smart Fan IV" mode

pwm[1-7]_mode
    - controls if output is PWM or DC level

        * 0 DC output
        * 1 PWM output

PS pwm[1-7]_mode DC/PWM is also in nct6687, all that remains is to find it.... PSPS where did you find out about NCT6687_REG_FAN_CTRL_MODE 0xA00 can you share the source/datasheet? but on NCT6683?

[SergeyMy]

@Fred78290 do you have a register map nct6687 because it takes a long time to search through reverse engineering :(

PS my MAG-B550M-MORTAR running an AMD 5700G is a home/family unit and is on more often than not. search requires constant system reboots with entering the BIOS :(:(

[Fred78290]

I have the same and my 5700G die, waiting for RAM. .

[SergeyMy]

NCT6687_REG_PWM_SOURCE_TEMP_VALUE(x) (0xca0 + (x)) :)

[SergeyMy]

I have the same and my 5700G die, waiting for RAM. .

I took an unnamed 2 to 16 from a Chinese supplier, happy as an elephant