Max PWM frequency BBB Motor Cape?

The title says it all. I am testing a GHI motor cape and above 10kHz it says: sysfs file problems. I do not know what such a file is. Going back to 2kHz and it works. I may need to increase the PWM frequency. Hence my question.
Thanks in advance,

The cape itself does not generate or handle frequencies. All is generated by BBB itself. I would check the BB docs on PWM limits and how to handle it.

Not sire if this would help - analogWrite