From the diagram the CPU fan is connected to gpio 79
I looked at the dmesg but it does not appear in the dmesg:
dmesg | grep -i pwm
[ 2.797773] pwm-backlight soc:lcd_backlight: supply power not found, using dummy regulator
and grepping for it in the dts shows it missing.
the bianbu kernel dts has the entry,
pinctrl_rpwm2_0: rpwm2_0_grp {
pinctrl-single,pins = <
K1X_PADCONF(GPIO_79, MUX_MODE2, (EDGE_NONE | PULL_DOWN | PAD_3V_DS4)) /* rcpu_pwm2 */
>;
};
So if you want to use the fan it is advised to compile bianbu’s uboot+opensbi and that kernel branch while the support for the board is getting upstreamed. (You may use my fork with a couple of additional patches).