Hi,

I am having trouble with BBB and using PWM. I am using Arch Linux and the 
following kernel "4.7.0-1-ARCH #1 Wed Jul 27 19:22:21 MDT 2016 armv7l 
GNU/Linux".

When I try to enable PWM (echo "am33xx_pwm" > 
/sys/devices/platform/bone_capemgr/slots) I get the following error in 
kernel log:

[ 72.786264] ehrpwm 48300200.pwm: Failed to get tbclk
[ 72.791291] ehrpwm: probe of 48300200.pwm failed with error -2

Any idea what is wrong?

Also, configuration of the PWM is very confusing. Can someone please 
explain how to configure PWM? For example I would like to use P9_16 as a 
PWM pin. What are the steps necessary to configure and use this pin as PWM?
I assume I have to also use this overlay [1] but it seems to binds it to a 
"pwm_test" driver which does not exist in my kernel tree. However, even 
without this driver it seems like just inserting the "am33xx_pwm" overlay 
gives me option to "export"
the pwm0 device: "echo 0 > /sys/class/pwm/pwmchip0/export". This gives me a 
folder "/sys/class/pwm/pwmchip0/pwm0/" that has nodes for duty_cycle, 
period, polarity, and enable.....

[1] "
https://github.com/beagleboard/devicetree-source/blob/master/arch/arm/boot/dts/bone_pwm_P9_16-00A0.dts
"

Thanks!

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