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, Marc -- "A mouse is a device used to point at the xterm you want to type in" - A.S.R. Microsoft is to operating systems .... .... what McDonalds is to gourmet cooking Home page: http://marc.merlins.org/ | PGP 7F55D5F27AAF9D08
