On Fri, 8 Jun 2007, Jiri Kosina wrote: > linux-usb-devel list added > > On Fri, 8 Jun 2007, Robert de Rooy wrote: > > > Jiri Kosina wrote: > > > On Thu, 7 Jun 2007, Robert de Rooy wrote: > > > > > > > > > > Yes I figured it was a hardware problem, but that was not really the > > > > point > > > > I was trying to raise ;). I would like, if possible for Linux to > > > > automatically fallback to USB 1.1 like Windows does (preferably with a > > > > suitable warning). > > > > > > > > > > What do you propose as a trigger for the kernel to fallback? > > > > > > You can work it around manually, just don't use ehci-hcd, can't you? > > > > > > > > Yes I can unload ehci-hcd, but I have one USB 2.0 device that strangely > > enough > > DOES work as such, and unloading ehci-hcd will cause that also to run at 1.1 > > speed. > > > > Clearly something is failing when plugging a device with ehci-hcd loaded, > > the > > driver seems to keep retrying indefinitely. Instead it would be nice if > > after > > a few tries it hands the device over to uhci-hcd. This seems to be the > > behaviour under Windows, so I was wondering if Linux could be made to do > > something similar.
Robert, it would help somewhat if you could build a kernel with CONFIG_USB_DEBUG turned on and post the dmesg log showing what happens when you plug in one of those non-working devices. Yes, in principle Linux can be made to switch over to full speed when high speed fails. But there are limitations: The switchover would work only for devices plugged directly into the computer, not for devices plugged into a high-speed hub. And some Linux systems (not regular PCs) have EHCI implementations that don't allow such a switch -- or if they do, I'm not aware of how to accomplish it. BTW, depending on the kind of failure the system does not keep retrying indefinitely. It gives up after four attempts. Alan Stern ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
