Details:

Performing receive sensitivity tests (EL_16 and EL_17) as defined in the USB-IF USB 2.0 Electrical Compliance Test Specification may invoke the problem described in Advisory i2091.

The issue was originally found while performing these tests using automation software, which increased USB signal amplitude while sending packets. The software was sweeping the amplitude from a value less than 100 mV to a value greater than 150 mV while verifying the device under test (DUT) NAK’d all packets below 100 mV and NAK’d no packets above 150 mV. However, increasing the amplitude through the squelch threshold while sending valid packets may lock the PHY as described in Advisory i2091.

Workaround(s):