On Sat, November 21, 2015 3:46 am, Peter Stuge wrote: > Patrick Shirkey wrote: >> I have read various forum posts and some of the archive from this list >> about the following error message: >> >> Not enough host controller resources for new device state >> >> Some people have had success with disabling XHCI at the BIOS level. >> >> That seems to be an unnecessary work around to me given we are >> progressing >> towards USB4 in the not too distant future. >> >> Is there a definitive explanation other than "no one had time/resources >> to >> work on this issue yet" why we cannot have more than 30 odd devices >> connected with XHCI enabled? > > Yes. > > The xHCI standard (not USB 3, but the standard that SuperSpeed > capable hardware on the PC side - host controllers - implement) > introduced an allowance for host controllers to support a significantly > smaller number of attached devices than described in the USB 2.0 spec. > > Some non-EHCI high speed capable host controllers in embedded systems > are known to have such aribtrary limitations too, but the Intel xHCI > implementation was the first I encountered in desktop/laptop hardware. > > Did hardware vendors decide in the standards bodies that users will > now have to choose between SuperSpeed and 127 possible devices? > Thanks for your detailed reply. I will have to take your lead on that. It would be nice if we were "able" to choose rather than "had" to choose. > >> I am available to assist with debugging this issue if there is a way to >> make it work. > > You essentially have to educate yourself on silicon level (ie. what > hardware IP is being used in which consumer products) to sustain a > dependency on 127 possible devices per bus. > > I guess you'll find that there are only very few xHCI IPs out there, > probably just three or four. I wouldn't be surprised if they all have > the same, or similar, limitations. > > Is there anything I can do at the system level to avoid disabling xHCI at the BIOS level? -- Patrick Shirkey Boost Hardware Ltd -- 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
