Bin Liu wrote: > I have a ARM SoC which has a dwc3 drd controller, to validate if there > is a limit of max device connections, I connected multiple hubs, then > keyboards and mice. > > When plugged in the 32th device, xHCI shows the following message and > the numeration failed. > > Not enough host controller resources for new device state. > can't set config #1, error -12 > > Then plugging in more keyboards or mice, this message always happened. > But then MSC devices were still enumerated correctly at this point. So > it seems the issue is only related to interrupt transfers? > > I am trying to understand if this is hardware or xHCI driver > limitation. Anyone has any pointers how to debug this issue? I don't know if it is the reason for what you experience above, but xHCI allows for host controller hardware to limit the number of devices that can successfully be attached - which IMO permits xHCI host controllers to be generally incompatible with the USB specification. http://marc.info/?l=linux-usb&m=139654353325844 //Peter -- 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
