Mathias Nyman wrote: > On 10.4.2021 3.47, Thinh Nguyen wrote: >> If an eSS device with active periodic transfers is disconnected from the >> DWC_usb31 (v1.90a and prior) host controller at root port, the host >> controller may not detect a disconnection. By active transfers, it >> means that the endpoint is not in flow control, and there are active >> Transfer Descriptors available for the host to initiate transfers to the >> endpoint. This issue can occur if the endpoint periodic interval is in >> 2ms, 4ms, or 8ms. >> >> In addition, the host controller will not be able to detect a new device >> connection while the disconnection is not processed. The controller will >> set the link state of the affected port to eSS_INACTIVE. >> >> To workaround this, have the xHCI driver polls for the eSS root port >> status every 2 seconds. If eSS_INACTIVE state is detected, initiate a >> fake connection change to stop all the active endpoints and start >> polling for new connection change. > > > If this only happens with active periodic transfers can we skip the polling > and check port link state in the transfer error event handling? > > Like in the previous case there the periodic device was behind a hub. > No, this occurs with an application with interrupt endpoint (but also affects isoc). We may not get a transfer completion event to notify to check for port link state. I hope this change is not too intrusive since we can reuse a timer polling for port status. Thanks, Thinh
