GPIO07 doesnt work as PWM

Robotics & Edge Computing Jetson & Embedded Systems Jetson Nano
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1

I find that I’m unable to use GPIO07 (LCD_BL_PWM) as a PWM. Symptoms are very similar to this prior post:

I’m on a newer version of L4T: 32.5.1. By default the PWM is taken by led_pwm, so I disabled that from the menuconfig. I have selected PM3_PWM0 in the pinmux spreadsheet. I am using other GPIO14 as PWM with similar selections in PinMux and it works correctly, I don’t understand why I’m unable to control GPIO07 as a PWM the same way. GPIO07 does show as PWM0 when I run the command:
root@nvidia-desktop:/sys/kernel/debug/pinctrl/700008d4.pinmux# cat pinmux-pins

I am able to use GPIO07 as a an ordinary GPIO.

Is it possible that disabling the LED_PWM feature in menuconfig I’ve somehow disabled the PWM entirely? If so, what is the correct procedure to use PWM0 as a GPIO PWM? Are there any steps that may help to diagnose the issue?

2

Hi, I found a solution in another post though it seems a bit hacky:

The only way I could find to get this PWM to work is with setting some registers using the busybox utility:

busybox devmem 0x700031fc 32 0x45
busybox devmem 0x6000d504 32 0x2

The post that helped was here:

5

Glad to know issue resolved.