Hi,
The Xavier TRM 1.4p says this about USB 3.1 Ports:
TRM
9.2.2.1.2 USB 3.1 Ports
USB 3.1 ports support both Generation 1 SuperSpeed USB and Generation 2 SuperSpeedPlus
USB 10 Gbps transfer rates.
Note that due to throughput limitations in the xHCI controller, USB 3.1 port 0 and port 3 are
connected to the same SuperSpeedPlus hub to share 10 Gbps total bandwidth, while
USB 3.1 port 1 and port 2 share another 10 Gbps total bandwidth. Note also that in the case of
two SuperSpeed devices connected to the same SuperSpeedPlus hub, due to scheduling policy
reasons each SuperSpeed device may not be able sustain the full SuperSpeed unit bandwidth
if the other is device is active.
TRM Photo
Figure 9.3
This photo makes it look like P0 and P1 are attached to the same SuperSpeedPlus hub, and then
P2 and P3 are attached to a different SuperSpeedPlus hub, which conflicts with TRM documentation.
The area in the “XUSBA” box is what convinced us that P0+P1 shared a USB hub and P2+P3 shared the other USB hub.
This is a problem because we have our own carrier board and wired USB ports P0 and P1 together
to a series of high bandwidth devices instead of wiring P0+P3 together… and we are seeing
bandwidth issues.
Xavier Data Sheet
1.9.4.3 USB 3.1 (Host) Operation
USB 3.1 ports support both Generation 1 - SuperSpeed USB and Generation 2 - SuperSpeed USB
10Gbps transfer rates. USB 3.1 port 0 and port 3 share one 10Gbps unit bandwidth, while USB
3.1 is allocated a separate 10Gbps unit bandwidth. All USB 3.1 ports support hardware initiated
U1 and U2 link power management as well as software initiate U3 (suspend) link power
management.
Which Xavier USB wiring information is correct? The TRM text and datasheet text or the TRM diagram?
Thank you,
andy