linux-wireless: realtek rtl8192cu user-space driver for Monitor Mode: about debug mechanism

Hi Larry, Chaoming and community,

I am trying to do user-space driver for Monitor Mode only for rtl8192cu.

My approach is:
1) Remove unnecessary functions from kernel driver, then verify kernel 
driver works with Monitor Mode.
    -- Purpose is to keep the code minimum.
2) Re-do the code at user-space by modelling kernel driver, e.g. 
rtl92cu_hw_init()

My current status is that I can download rtl8192cu firmware 
(rtl8192cufw_TMSC.bin). But, I can not read any WiFi frames from Bulk In 
Endpoint (ep0). I guess there could be 2 possible issues:
a) I do not init rtl8192cu correctly.
b) Monitor Mode frames are ready in rtl8192cu adapter to be read out, 
but I incorrectly read Bulk In Endpoint (at user-space).

As I am lack of a debug mechanism, is there a register in rtl8192cu 
which shows there is data ready to be read out via Bulk In Endpoint and 
I can read this register back?

I noticed rtl8192cu has an Interrupt Endpoint, what is this for?

Thanks.

xuebing