VIM1/2/3/Edge1

Edit /boot/env.txt to add the pwm node to overlays node if it doesn't exist.

Take VIM3 as an example to enable PWM_F, you need to add pwm_f node to overlays node if it doesn't exist.

overlays=uart3 pwm_f i2c3 i2s os08a10 watchdog

After reboot, you will see the pwm device node.

$ ls /sys/class/pwm/pwmchip4
device  export  npwm  power  subsystem  uevent  unexport

VIM3L

Edit /boot/env.txt to add the pwm node to overlays node if it doesn't exist.

Take VIM3L as an example to enable PWM_F, you need to add pwm_f node to overlays node if it doesn't exist.

overlays=uart3 pwm_f i2c3 i2s watchdog

After reboot, you will see the pwm device node.

$ ls /sys/class/pwm/pwmchip0
device  export  npwm  power  subsystem  uevent  unexport

VIM3 with 5.15 kernel

Edit /boot/dtb/amlogic/kvim3.dtb.overlay.env to add pwm node to fdt_overlays node if it doesn't exist.

You need to add pwm_f to node fdt_overlays if it doesn't exist to enable PWM_F.

fdt_overlays=pwm_f

After reboot, you will see the pwm device node.

VIM3L with 5.15 kernel

Edit /boot/dtb/amlogic/kvim3l.dtb.overlay.env to add pwm node to fdt_overlays node if it doesn't exist.

You need to add pwm_f to node fdt_overlays if it doesn't exist to enable PWM_F.

fdt_overlays=pwm_f

After reboot, you will see the pwm device node.

VIM4

Edit /boot/dtb/amlogic/kvim4.dtb.overlay.env to add pwm node to fdt_overlays node if it doesn't exist.

You need to add pwm_f to node fdt_overlays if it doesn't exist to enable PWM_F.

fdt_overlays=pwm_f

After reboot, you will see the pwm device node.

$ ls /sys/class/pwm/pwmchip4
device  export  npwm  power  subsystem  uevent  unexport

VIM1S

Edit /boot/dtb/amlogic/kvim1s.dtb.overlay.env to add pwm node to fdt_overlays node if it doesn't exist.

You need to add pwm_f to node fdt_overlays if it doesn't exist to enable PWM_F.

fdt_overlays=pwm_f

After reboot, you will see the pwm device node.

$ ls /sys/class/pwm/pwmchip0
device  export  npwm  power  subsystem  uevent  unexport

VIM4

The PWM function is disabled by default, you need to modify the dts to enable it.

diff --git a/arch/arm64/boot/dts/amlogic/kvim4.dts b/arch/arm64/boot/dts/amlogic/kvim4.dts
--- a/arch/arm64/boot/dts/amlogic/kvim4.dts
+++ b/arch/arm64/boot/dts/amlogic/kvim4.dts
 &pwm_ef {
+    pinctrl-names = "default";
+    pinctrl-0 = <&pwm_f_pins>;
        status = "okay";
 };
 
diff --git a/arch/arm64/boot/dts/amlogic/kvim4n.dts b/arch/arm64/boot/dts/amlogic/kvim4n.dts
--- a/arch/arm64/boot/dts/amlogic/kvim4n.dts
+++ b/arch/arm64/boot/dts/amlogic/kvim4n.dts
 &pwm_ef {
+    pinctrl-names = "default";
+    pinctrl-0 = <&pwm_f_pins>;
        status = "okay";
 };
 
diff --git a/arch/arm64/boot/dts/amlogic/mesont7_an400-panel.dtsi b/arch/arm64/boot/dts/amlogic/mesont7_an400-panel.dtsi
--- a/arch/arm64/boot/dts/amlogic/mesont7_an400-panel.dtsi
+++ b/arch/arm64/boot/dts/amlogic/mesont7_an400-panel.dtsi
@@ -1442,13 +1442,13 @@
 
        backlight1{
                compatible = "amlogic, backlight-t7";
-               status = "okay";
+               status = "disabled";
                index = <1>;
                key_valid = <0>;
                pinctrl-names = "pwm_on",
                                "pwm_off";
-               pinctrl-0 = <&pwm_f_pins>;
-               pinctrl-1 = <&bl1_pwm_off_pins>;
                pinctrl_version = <2>; /* for uboot */
                interrupts = <0 197 1

VIM1S

The PWM function is disabled by default, you need to modify the dts to enable it.

--- a/arch/arm64/boot/dts/amlogic/kvim1s.dts
+++ b/arch/arm64/boot/dts/amlogic/kvim1s.dts
@@ -1411,8 +1411,8 @@
 };
 
 &pwm_ef {
-       /*pinctrl-0 = <&pwm_f_pins2>;*/
-       /*pinctrl-names = "default";*/
+       pinctrl-0 = <&pwm_f_pins2>;
+       pinctrl-names = "default";
        status = "okay";
 };

VIM1/3/4

echo 1 | sudo tee /sys/class/pwm/pwmchip4/export
echo 1000000 | sudo tee /sys/class/pwm/pwmchip4/pwm1/period
echo 500000 | sudo tee /sys/class/pwm/pwmchip4/pwm1/duty_cycle
echo 1 | sudo tee /sys/class/pwm/pwmchip4/pwm1/enable

VIM2

echo 1 | sudo tee /sys/class/pwm/pwmchip1/export
echo 1000000 | sudo tee /sys/class/pwm/pwmchip1/pwm1/period
echo 500000 | sudo tee /sys/class/pwm/pwmchip1/pwm1/duty_cycle
echo 1 | sudo tee /sys/class/pwm/pwmchip1/pwm1/enable

VIM3L/1S

echo 1 | sudo tee /sys/class/pwm/pwmchip0/export
echo 1000000 | sudo tee /sys/class/pwm/pwmchip0/pwm1/period
echo 500000 | sudo tee /sys/class/pwm/pwmchip0/pwm1/duty_cycle
echo 1 | sudo tee /sys/class/pwm/pwmchip0/pwm1/enable

VIM1/3/4

echo 0 | sudo tee /sys/class/pwm/pwmchip4/pwm1/enable

VIM2

echo 0 | sudo tee /sys/class/pwm/pwmchip1/pwm1/enable

VIM3L/1S

echo 0 | sudo tee /sys/class/pwm/pwmchip0/pwm1/enable