On 12/19/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > On 12/19/06, Jon Smirl <[EMAIL PROTECTED]> wrote: > > > That's a pretty bad scheduler if it can't schedule a single 12Mb > > device on a 480Mb hub. > > It's only sharing the hub with a USB keyboard. The audio being sent to > > it is less than 1Mb. > > That's not the problem; it has trouble scheduling the bandwidth on the > FS side, and it's even worse when shared with LS devices (keyboard) > which are only 1mbps and incur substantial timing penalties switching > back and forth from one mode to the other. > > A USB 2.0 hub is not a fully autonomous unit, it has to be driven, in > software, by the host controller. It does not make > scheduling/budgeting decisions for itself. That's the portion of the > mainline ehci driver that's lacking.
I was giving the hub more credit than it deserved. I thought it was doing store and forward so that it was talking 480Mb to the PC and then 1Mb, 12Mb or 480Mb to the peripherals. If I understand correctly it is switching the 1Mb or 12Mb traffic onto the PC at 1Mb or 12Mb which would make scheduling harder. > In any case, this is fully fixed in the mm kernels, there are > unrelated integration issues to be finished before it makes it into > mainline. > > > I will look for this. Meanwhile I plugged my audio device into a USB > > port directly on the PC and it works fine. > > Yes, because that is skipping EHCI entirely and forcing the port to > use a 1.1 companion controller (UHCI or OHCI). yes, it is using UHCI > > Your problems were occurring because of an FS device on a 2.0 hub on > an EHCI controller. That is what I have. > > Monty > -- Jon Smirl [EMAIL PROTECTED] ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
