Details:

The USB 2.0 PHY may hang in response to a USB wake-up event that occurs within 3 microseconds of the USB controller entering suspend. This PHY hang can only be recovered via a power cycle as warm reset is ineffectual.

Workaround(s):

Note: this workaround is only applicable if USB is not the primary boot mode. If USB is the primary boot mode, no workaround is available.

In order to prevent this issue from occurring, a specific order of operations must be observed during the USB controller initialization process:

1. Remove USB controller reset via the LPSC.
2. Set PLL_REG12.pll_ldo_ref_en field (bit 5) in PHY2 region to '1'.
3. Set PLL_REG12.pll_ldo_ref_en_en field (bit 4) in PHY2 region to '1'.
4. Proceed with normal USB controller initialization.