On Wed, 30 Jan 2013, [big5] �x�R��wrote: > Hi all, > > We try to reproduce the problem on general desktop with ubuntu 12.04.1 and 12.10, and got some information below: > > 1. If we use xHci with Ti TUSB7340 chip, do bus reset or plug/unplug 1000+ times, the host fail to configure the device. > If we use xHci with Fresco chip, it operats without error. > > 2. If the usb device contains only Control/Bulk type endpoints, it's all right. > If it contains interrupt/isoc (periodic) endpoint, it will fail with bandwidth error. > I check the source and find that the bandwidth_error is the TRB_completion_code of configure_endpoint command. > > In addition, I try to study the usb_reset_and_verify_device and want to consult the following question. > > When reseting a device, hcd will invoke usb_hcd_alloc_bandwidth, > this function will drop the endpoints and add the endpoints. > > When executing drop_endpoint, the function shows error message xHCI called with disabled ep. > And I confirm that ep_state of end point context is in disabled state this time. Why is the endpoint already disabled? It shouldn't be. > Then usb_hcd_alloc_bandwidth invokes add_endpoint. > Last, sending a configure endpoint command to complete the change. > > The xHCI spec says configure endpoint should ignore disabled endpoints drop flag and do nothing. > So the source is correct according to spec. > But the overall behavior is adding the endpoint without dropping the old endpoint. > > Is this what we want? Don't we need dropping endpoints to release the bandwidth and/or resource > before the endpoints goes to disabled state without freeing bandwidth? Yes. It would work okay if the endpoint wasn't already disabled. Can you figure out how the endpoint became disabled in the first place? Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
