On Sat, 6 Aug 2005, Erik Walthinsen wrote: > Rogier Wolff wrote: > > What happens if you plug the mice into the motherboard directly. (for > > now: No keyboards!) > > Tried various combinations of direct and hub (powered and not) > connections with no luck in removing the non-deterministic behavior. > > Then I noticed that both ehci_hcd and uhci_hcd were being loaded by the > Ubuntu scripts. Some messing around with them yields the answer: > > ehci_hcd is broken. > > uhci_hcd works just fine so far every single time, with the > configuration I'm after in the long run: one hub per workstation, each > hub connected to the root hub. I don't even need to power the hubs > directly, which is *great* for both cable and power management. Not > sure what the official power usage is on the mice, but I suspect each > keyboard/mouse pair isn't more than 25mA, and IIRC I have a budget of > 500mA total off the root hub. > > While I'd like to see ehci_hcd working before I leave (Sept. 4), I don't > need the 480Mbps capability currently, so I've just blacklisted ehci_hcd > and all is well.
This all sounds very familiar... ehci-hcd has a known problem with periodic IN transfers from low- and full-speed devices (like a mouse) attached through a high-speed hub. The computations involved in scheduling the transfers are pretty hairy, and the driver doesn't do an ideal job. As a result, if you try to attach too many mice to an EHCI controller, they won't work -- as you've seen. Just in the last week or two there has been some work to improve this, but it's going to take some time get everything working as it should. For now, you can work around your problem either by not loading ehci-hcd or by attaching the mice through a USB 1.1 hub instead of a USB 2.0 hub. Alan Stern ------------------------------------------------------- SF.Net email is Sponsored by the Better Software Conference & EXPO September 19-22, 2005 * San Francisco, CA * Development Lifecycle Practices Agile & Plan-Driven Development * Managing Projects & Teams * Testing & QA Security * Process Improvement & Measurement * http://www.sqe.com/bsce5sf _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-users
