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USB 3.1 xHC in Q370 chipset misbehaves if C3 state is enabled


We have the following setup:


Mainboard: HP EliteDesk 800 G4 TWR

CPU: Core i7-8700 3.20GHz

Chipset: Q370

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


Problem description:

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.







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Hello UEber, Thank you for posting on the Intel ® communities. I would like to mention that the problem you seem to be experiencing appears to be an integration problem, the integration was done by the manufacturer so it is important for you to report this issue to the system manufacturer and ask for their assistance directly, they should be able to provide you with a fix or driver to address the situation if applicable. Regards, David V Intel Customer Support Technician Under Contract to Intel Corporation
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