On Thu, 20 Dec 2018, Marc MERLIN wrote: > On Mon, Dec 17, 2018 at 09:45:44PM -0800, Marc MERLIN wrote: > > On Mon, Dec 17, 2018 at 10:52:57AM -0500, Alan Stern wrote: > > > > Point taken. I think I was thinking about USB ports that were routed to > > > > either a xHCI or an EHCI chip depending on what's plugged into them, but > > > > seems that I didn't quite understand how that worked. > > > > > > It varies. For example, my office computer does exactly what you were > > > thinking: It routes SuperSpeed connections to the xHCI controller and > > > it routes high speed connections (even on the same port!) to one of the > > > EHCI controllers. > > > > Thanks, so I'm not crazy, I thought I had seen this before. > > I had a look at my work server today and thankfully it at least had a > > USB3 setting, which when I turned it off, xhci was replaced with ehci as > > expected. > > Again, thanks Alan. > I just wrote a web page that hopefully google will index and show in > addition or in front of the other page I mentioned and that wasn't clear > enough about the 32 device limit being due to the xhci controller being > active, not due to USB3 devices being on the bus, or not. > > http://marc.merlins.org/perso/linux/post_2018-12-20_Getting-Around-USB3-xhci-32-Device-Limit-_Max-number-of-devices-this-xHCI-host-supports-is-32_.html > > Further reading: > https://forums.intel.com/s/question/0D50P00004905stSAA/hardware-limitations-on-usb-endpoints-xhci?language=en_US > > Thanks again, You're welcome. If you have any further questions, you know where to go. :-) Alan Stern
