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. ;-) Thanks, Dwayne Fontenot System specs: Host is a custom 32-bit PowerPC MPC8245 based board with a NEC D720101 host controller. Linux kernel version is 2.6.19. Hubs are based on a Philips ISP1521 7-port controller. Peripherals have a Cypress EZ-USB FX2LP peripheral controller. USB bus topology is four hubs attached to host, one hub daisy-chained from each of those four, and additionally five peripherals per hub. ------------------------------------------------------------------------- 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
