On Wed, Feb 11, 2015 at 12:54:52PM -0600, Bin Liu wrote: > 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... no, you're hitting the limit alright :-) You said it dies after the 32nd device right ? I think each device is taking up 2 slots. Just a guess, probably worth counting how many slots are used by each device. -- balbi
Attachment:
signature.asc
Description: Digital signature
