Thunderbolt issue with Windows10

Question

USB device when connected to a thunderbolt port, we can see a difference in the behaviour compared to a regular type-c or USB port.

USB IN transfers Host reads and sends ACK back to device is happening in bursts. Each burst is about 8 1024 bytes transfer. The last packet in the burst will have EoB set to 1 indicates the end of burst.

The difference here is, on a regular Type-C/USB3 port, the ACK response from the host happens very fast less than 2.5us. However, on a thunderbolt port, the ACK for the last packet with EoB set is acknowledged very late about 80us delay. This is, in fact, a violation of tHostAckResponse timer in the USB spec. Also, this is causing a performance issue as the device cannot start next transfer even when the next burst is ready as ACK for the previous packet is not received. Hence this causes huge latencies and makes high-resolution video frames to be dropped. This issue was not present in Windows 10 1709. Issue started appearing from version 1803.

Answer 1

Hi,

Have you checked the issue in the latest version of windows 10(version 20H2)?
Thank you for the information.
As far as I know, there is no related known issues has been offered.
Hope above information can help you.

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