On Sat, 11 Sep 2004, Manoj Bhatta wrote: > Hi , > > My USB 1.1 Full Speed (12mbps) device , which is > having one isoc endpoint of 840 bytes when tries to > read data through the isoc endpoint by making 20 URBs > , each URB having 840*10 (10 frames) bytes and it > takes more time to read data from device almost > 600millisec . > How can i overcome this problem . Do i need any > configuration for bandwidth ? > > > I got kernel messages like the following . i am > using 2.6.4 kernel , with USB Controller INTEL UHCI . > > Sep 9 20:07:30 linux kernel: usb 1-1.4: > usb_check_bandwidth would have FAILED: > 869 + 66 = 935 usec > Sep 9 20:07:30 linux kernel: usb 1-1.4: > usb_check_bandwidth would have FAILED: > 935 + 66 = 1001 usec > Sep 9 20:07:30 linux kernel: usb 1-1.4: > usb_check_bandwidth would have FAILED: > 1001 + 66 = 1067 usec > Sep 9 20:07:30 linux kernel: usb 1-1.4: > usb_check_bandwidth would have FAILED: > 1067 + 66 = 1133 usec > Sep 9 20:07:30 linux kernel: usb 1-1.4: > usb_check_bandwidth would have FAILED: > 1133 + 66 = 1199 usec > Sep 9 20:07:30 linux kernel: usb 1-1.4: > usb_check_bandwidth would have FAILED: > 1199 + 66 = 1265 usec > Sep 9 20:07:30 linux kernel: usb 1-1.4: > usb_check_bandwidth would have FAILED: > 1265 + 66 = 1331 usec > Sep 9 20:07:30 linux kernel: usb 1-1.4: > usb_check_bandwidth would have FAILED: > 1331 + 66 = 1397 usec > Sep 9 20:07:30 linux kernel: usb 1-1.4: > usb_check_bandwidth would have FAILED: > 1397 + 66 = 1463 usec > Sep 9 20:07:30 linux kernel: usb 1-1.4: > usb_check_bandwidth would have FAILED: > 1463 + 66 = 1529 usec
The bandwidth management for isochronous transfers in the UHCI driver is messed up. So don't worry about those error messages. As for why the transfers take 600 ms instead of 200 ms... I don't know. The development and debugging of the iso. code in the UHCI driver has lagged behind the other transfer types. You can learn more by printing out the urb->start_frame values for each URB you submit, and compare those values to the result of calling urb->dev->bus->op->get_frame_number(). Also, it would be a good idea for you to upgrade to 2.6.8.1 or 2.6.9-current. Alan Stern ------------------------------------------------------- This SF.Net email is sponsored by: YOU BE THE JUDGE. Be one of 170 Project Admins to receive an Apple iPod Mini FREE for your judgement on who ports your project to Linux PPC the best. Sponsored by IBM. Deadline: Sept. 13. Go here: http://sf.net/ppc_contest.php _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
