Peter, On Tue, Feb 10, 2015 at 10:08 PM, Peter Stuge <peter@xxxxxxxx> wrote: > 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 Thanks for the pointer. I checked HCSPARAMS1 register on my platform, its value is 0x02000440, which means it has 64 device slots. So I think my issue is on elsewhere. Keep looking... Regards, -Bin. > > > //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
