We have the following setup:
Mainboard: HP EliteDesk 800 G4 TWR
CPU: Core i7-8700 3.20GHz
OS: Windows 10 Pro 1803 x64
BIOS: C3 states enabled
USB device tree:
Q370 xHC root hub --> USB 2.0 hub --> 4 full speed devices with one interrupt IN endpoint each
Q370 xHC root hub --> USB 3 Gen1 camera
We observed that the timing of the IN tokens sent to the full speed interrupt IN endpoints is not correct. The CSPLIT command is deferred by one microframe which violates the USB specification (USB 2.0 spec 11.18.4). The USB analyzer screen shot below illustrates the issue.
The issue disappears if we disable C3 states via BIOS.
We can provide more details such as USB bus traces, if desired.
Is this a known issue in the Q370 chipset?
Thanks in advance for your feedback.