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? > 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. //Peter -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
