[beagleboard] Beaglebone Black Rev C PWM Questions

Hi all,

I'm running RCN's 3.8.13-bone56 from the eMMC on my BBB Rev C. I'm wanting
to used the PWM on P9_14 and P9_16 (EHRPWM1A and B). I've added
am33xx_pwm,bone_pwm_P9_14,bone_pwm_P9_16 to my uEnv.txt
capemgr.enable_partno line to enable the PWM pins and drivers.

My question is, short of modifying the bone_pwm_P9_xx dts files/rebuild
kernel, how does one change the period? I know both P9_14 and P9_16 have
to have the same period and I'm curious if it is possible to change the
period for both to a new (same) value? I'm also a bit confused as to what
sysfs folders to I use. I've read conflicting instructions as to where to
change period and duty values:

(after echo 0 > /sys/class/pwm/export)

So, is it possible to change period without modifying the defaults in the
dts files and which of the period / period_ns files should I be using to
change period?