topic No PWM in i.MX Processors

No PWM

tlamarc — Fri, 19 Apr 2024 13:11:14 GMT

I am trying to get a pwm signal on gpio 1 1 for an i.MX7s processor. Here is my device tree configuration but I see nothing on the pin. Any help would be greatly appreciated.

/ {

pwm-leds {

compatible = "pwm-leds";

pwm_led1 {

label = "pwm_led1";

pwms = <&pwm1 0 100000 50000>;

max-brightness = <255>;

};

&pwm1 {

pinctrl-names = "default";

pinctrl-0 = <&pinctrl_pwm_led1>;

status = "okay";

};

&iomuxc {

pinctrl_pwm_led1: pwm_led1 {

fsl,pins = <

MX7D_PAD_LPSR_GPIO1_IO01__PWM1_OUT 0x14

};

Re: No PWM

JosephAtNXP — Mon, 22 Apr 2024 17:53:03 GMT

Hi,

Thank you for your interest in NXP Semiconductor products,

Please change the driver according to this document.

Also, this solution provided by a colleague may help debug this issue.

Regards

Re: No PWM

tlamarc — Tue, 23 Apr 2024 17:30:39 GMT

I updated the line from: compatible = "pwm-leds";

to: compatible = "fsl,imx7d-pwm";

but I still have no pwm signal on the pin,

Re: No PWM

JosephAtNXP — Fri, 26 Apr 2024 16:39:28 GMT

Hi,

You can base on 7d-sdb device tree,

pwm1: pwm@30660000 { compatible = "fsl,imx7d-pwm", "fsl,imx27-pwm"; reg = <0x30660000 0x10000>; interrupts = <GIC_SPI 81 IRQ_TYPE_LEVEL_HIGH>; clocks = <&clks IMX7D_PWM1_ROOT_CLK>, <&clks IMX7D_PWM1_ROOT_CLK>; clock-names = "ipg", "per"; #pwm-cells = <3>; status = "disabled"; }; ... &pwm1 { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_pwm1>; status = "okay"; }; ... - backlight: backlight { - compatible = "pwm-backlight"; - pwms = <&pwm1 0 5000000 0>; - brightness-levels = <0 4 8 16 32 64 128 255>; - default-brightness-level = <6>; - status = "okay"; - };

I reproduced in 8mp-evk with the device tree,

pwm1: pwm@30660000 { compatible = "fsl,imx8mp-pwm", "fsl,imx27-pwm"; reg = <0x30660000 0x10000>; interrupts = <GIC_SPI 81 IRQ_TYPE_LEVEL_HIGH>; clocks = <&clk IMX8MP_CLK_PWM1_ROOT>, <&clk IMX8MP_CLK_PWM1_ROOT>; clock-names = "ipg", "per"; #pwm-cells = <3>; status = "disabled"; }; ... &pwm1 { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_pwm1>; status = "okay"; };

And these steps from the post I mentioned,

root@imx8mpevk:~# cat /sys/class/pwm/pwmchip0/npwm 1 root@imx8mpevk:~# echo 0 > /sys/class/pwm/pwmchip0/export root@imx8mpevk:~# ls /sys/class/pwm/pwmchip0/pwm0/ capture duty_cycle enable period polarity power uevent root@imx8mpevk:~# echo 10000 > /sys/class/pwm/pwmchip0/pwm0/period root@imx8mpevk:~# echo 2000 > /sys/class/pwm/pwmchip0/pwm0/duty_cycle root@imx8mpevk:~# echo 1 > /sys/class/pwm/pwmchip0/pwm0/enable

Regards,