On Thu, 9 Apr 2009, Kung James wrote: > Actually, this bug really cause some problem. > > I plug an USB mouse and an USB sound card in to USB2.0 HUB. > When I play music with the 192 byte data in every frame, the mouse will be > port reset by kernel. Because the start split of QH of intr. IN > endpoint is scheduled > at the first micro frame, and the SITD of isoc. OUT endpoint is scheduled > at the first and the second micro frame. At the first micro frame, the > HUB need to execute 188 byte start split isoc. OUT transaction and a start split > intr. IN transaction. Some HUBs can successfully execute the two split > transaction > at the first micro frame, but some HUBs (e.g. NEC µPD720114) can not. Can you explain more fully? I'm just starting to go through the scheduling code in ehci-sched.c, so I don't understand it all yet. Why does this patch fix the problem? Every USB-2.0-compliant hub should be able to handle those two start-split transactions in the same uframe. How far should we go to accomodate buggy hubs? Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
