On Wed, 6 Jun 2007, Dwayne Fontenot <[EMAIL PROTECTED]> wrote: > > Hi, > > I'm seeing behavior I don't understand relating to USB 2.0 interrupt > transfers. > > > I have 40 USB 2.0 peripherals plus eight USB 2.0 hubs on a single USB bus. > > Each of the 40 peripherals is posting a single 8-byte interrupt transfer > within > a window of approximately 2ms. > > The unexpected behavior is that I only get 29 interrupt transfers at my USB > device driver. > > So far it's always 29, no more and no less. > > > The host is running kernel 2.6.19 with the ECHI driver and no UHCI/OHCI. > > The peripherals are all USB 2.0 High Speed devices. > > > I've been reading the USB and EHCI specs and the linux USB subsystem code and > have been > unable to find the cause of the 29 message limit. > > I would appreciate any thoughts, hints on where to look in the code, or > explanations as to why the above behavior is a feature. ;-)
What you really need is a USB bus analyzer. Unfortunately they aren't cheap. Can you really be certain that all 40 devices are ready with an interrupt transfer? Do you know that your driver has submitted 40 interrupt URBs? Have you tried using usbmon (see Documentation/usb/usbmon.txt)? Have you tried turning on CONFIG_USB_DEBUG and then looking at the debugging files under /sys/class/usb_host/usb_host1? 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
