PWM issues on using timer (RTL8195)

Hi ,
I am using standard SDK for PWM and timer.
I found that there is conflict by using PWM and timer at the same time.
But it is not always conflict at all, it seems having some patterns on which timer conflict on which PWM port. for example,

gtimer_init(&mytimer1, TIMER2);
will cause failure on GPIOC_1 PMW1,
and TIMER3 failed on GPIO_2 PWM2.

I guess the under layer library is using timers to generate timer.
Just wondering if there is a relationship table of PWM and TIMER on the document?