Enabling PWM in the 6.19.6 kernel

General Discussion
1

Hi - I’ve just (few days ago) spun a new kernel for my beagle cluster. New kernel boots up fine, and the PWM overlay has been applied.

What’s strange is I can’t bring up pwm, specifically:

echo 0 > /sys/class/pwm/pwmchip0/export
echo 1 > /sys/class/pwm/pwmchip0/export
echo 0 > /sys/class/pwm/pwmchip1/export
echo 1 > /sys/class/pwm/pwmchip1/export

This works - and it creates the A and B channels in pwm 0 and 1.

But when I try and enable the pwm:

echo 1 > /sys/class/pwm/pwmchip0/pwm0/enable
echo 1 > /sys/class/pwm/pwmchip0/pwm1/enable
echo 1 > /sys/class/pwm/pwmchip1/pwm0/enable
echo 1 > /sys/class/pwm/pwmchip1/pwm1/enable
bash: echo: write error: Invalid argument
bash: echo: write error: Invalid argument
bash: echo: write error: Invalid argument
bash: echo: write error: Invalid argument

I have the various the ehrpwm modules in the kernel, current they are in by default - but just spinning a new kernel with the as modules - so I can see what parameters I can set.

So just posting here in case anyone has seen something similar? I must have miss set something in the kernel config, but what that is I’ve not been able to find despite extensive checking.

Anyone any ideas?

2

Have you looked at the kernel driver to see if you need to set something
like maybe the period, before it’ll accept your enable command?

1 Like
3

Bingo - yes that worked ….

4

Outstanding!