On Wed, May 10, 2017 at 03:39:27AM +0000, Wei Zhang wrote: > Hi Keith and Wes, > > I wonder if getting an All 1’s read on the DPC status register is a > valid scenario. The DPC register is on the switch, why would the > status register returns All 1’s even if the device is removed? Ah, this isn't about the downstream device precense. This is about the DPC switch device itself, like if you pull the cable out of the enclosure. Reading anything off the DSPs in it will see all 1's.