Issues with PWM control via sysfs

[jerivas]

Hi, I've added PWM support via sysfs to my pcDuino 3 following these instructions: http://learn.linksprite.com/pcduino/arduino-ish-program/pwm/add-pwm-sysfs-support-for-pcduino-pcduino3/

Everything works fine... kind of. These are a few bugs I've found:

1. It seems that whenever I enable pins, their max_levels change. Before enabling pins 5, 6, they report a max level of 255, after enabling them, they report 39. Before enabling pins 3, 9, 10, 11; they report a max level of 32. After enabling, they report a max level of 640.
2. Pins 3, 9, 10, 11 are unable to maintain their assigned frequency if the CPU is busy with anything. I assigned a frequency of 50 Hz to them to drive some servos, but if I do pretty much anything with the pcDuino (like opening the web browser), the servos begin to stutter because of the jitter in the PWM signal. I guess these pins use software produce the PWM signal.
3. To work around the stutter problem, I decided to drive the servos with pins 5 and 6, because in my tests they are jitter-free. The problem is they have a very limited range (because their max level is only 32), which translates in a servo resolution of 30º per step.

I would like to know if there is a way to solve any of these issues:

1. Prevent the jitter in pins 3, 9, 10, 11
2. Or, increase the max_level in pins 5 and 6 (because they are suppossed to be 8-bit PWM)

Thanks.