On Wed, 22 Jul 2009, Michael Conrad wrote: > Hi, I've filed a bug at http://bugzilla.kernel.org/show_bug.cgi?id=13779 > and was asked to bring it here for discussion. > > The short of it is that I have a board that ends up with ehci and uhci on > the same interrupt, and in kernel 2.6.27 something changed that causes > these two to conflict in some way that causes a firmware upload to take > ridiculously long to complete on a USB 2.0 device. > > Thanks for any/all help. > > > Here's the text of the bug, for convenience: > > The 950Q TV tuner from Hauppauge uploads its firmware 64 bytes at a time > over > USB, when you tune a channel. In linux stock kernel 2.6.26 this works > fine, > but in 2.6.27 and later (tested up to .30) the firmware transfer takes 15 > minutes, rendering the device unusable. This bug is motherboard > dependent, and > working with Mike Krufky at Hauppauge (a dvb/v4l contributor) we have > determined that it is a resource conflict between ehci and uhci drivers. > > Our main diagnosis is that (using 2.6.30) by disabling the UHCI driver, the > firmware upload no longer exhibits the problem. Our main clue was that on > our > hardware, ehci and one instance of uhci were sharing an interrupt. They > were > also sharing an interrupt in 2.6.26, but did not have the slow transfer > problem > in that version of the kernel. The problem showed up in 2.6.27 and later. > > Our platform is an embedded Intel Atom board. Other systems with 2.6.30 > and > uchi enabled do not have this problem, however we have no other systems > where > ehci and uhci share an interrupt. > > We are willing to help debug and test. Let's concentrate on 2.6.30. First, build the kernel with CONFIG_USB_DEBUG enabled, just for the sake of thoroughness. Next, acquire a couple of usbmon traces showing what happens during the firmware upload both with and without uhci-hcd loaded. (See Documentation/usb/usbmon.txt for instructions.) Attach those traces to the bug report and let us know when they are ready. Also attach the dmesg log; it might contain some useful debugging information. 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
