I believe the logic for creating the signal phy_SuspendM_pad_o
is incorrect. The UTMI spec states that this signal is driven LOW
to put the transceiver into suspend mode.

The original code is:
assign SuspendM = (usb_suspend & !resume_req_s) | (LineState == 2'b10);

In looking at simulations, I see SuspendM changing state unexpectedly.

I believe the correct code should be:
assign SuspendM = ~(usb_suspend & !resume_req_s) | (LineState == 2'b10);

John Providenza