On Wed, 11 Feb 2015, Bin Liu wrote: > > The problem probably isn't the number of endpoints, but rather the > > scheduling entries for interrupt and isochronous endpoints. > > -12 return code in the log is due to COMP_ENOMEM (7, in Table 135 in > xHCI Specs) returned by the completion of configure endpoint command. > All in xhci_configure_endpoint() in xhci.c. > > Then in xHCI Specs Section 4.6.6 Configure Endpoint, and Section > 4.14.1.1 System Bus Bandwidth Scheduling, I got a feeling it is indeed > due to periodic scheduling, after certain amount of interrupt > (applicable to ISO as while) endpoints have been scheduled, there does > not have enough bus bandwidth left for new interrupt scheduling any > more. > > I am new to xhci, any comments for my suspicion? It could be that there is not enough bus bandwidth. Or it could be some other resource that the xHCI controller uses internally for the periodic scheduling. Either way, that's the reason you reach the limit. 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
