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.
I now have:
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
lspci:
00:1a.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB EHCI #2 (rev 05)
00:1d.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB EHCI #1 (rev 05)
05:00.0 USB controller: Fresco Logic FL1100 USB 3.0 Host Controller (rev 10)
Seems that my MB does have 2 EHCI controllers that get routed to
different slots and the good news is that I was able to plug at least 80
USB devices between them.
And with USB3 enabled, there was only a single xhci chipset:
00:14.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB xHCI (rev 05)
USB3 is the gift that keeps on giving on that motherboard: half the
controllers that each support 2 or 3x fewer devices.
Now, one weird problem left: when tuning off xhci, it also stopped the
M2 NVME from working. This makes no sense given that NVME is PCI, not
SATA which could be hosted on USB, right?
Either way, will look more into it tomorrow.
Thanks for your help
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
