On Fri, 11 Feb 2005, Steve Hosgood wrote: > OK, so I compiled a kernel with CONFIG_USB_DEBUG on, installed ehci_hcd > with debug=2, and ran my camera driver modified to attempt 40 fps reads > from the camera in 800x600 pixel mode, 8 bits per pixel. > > I get wedged as usual and I have to "kill -9" my viewer program from > elsewhere in order to rescue the situation.
Why do things get wedged instead of failing gracefully? > However, I also get no messages in /var/log/messages and nothing from > the output of 'dmesg' either. What did I miss? Nothing at all? Not even the normal kernel boot-up messages? > Meanwhile, I ran my driver with detailed debugging of its own and what I > see is like this: > > .... > Receive 32768 bytes from camera: add it to the image-buffer > Resubmit URB > Receive 32768 bytes from camera: add it to the image-buffer > Resubmit URB > Receive 20667 bytes from camera: add it to the image-buffer (that marks > the end of frame). This URB has been composed from 41 full 512 byte > bulk-packets plus one half-filled 512 byte bulk-packet. > Resubmit URB > > [no more IRQs hit my callback function over the next tenth of a second] > > The timebomb goes off. > Tell the camera to stop streaming. > Release all URBs. > > This is as close as I can get to diagnostics, since I don't have useful > access to the next layer down. Is it possible that the camera stopped transmitting data on its own, and that's why your completion routine doesn't get called? You said before that your bus analyzer showed the computer had stopped polling for bulk data. Are you sure that's what happens? There are files you can read, containing debugging data for the ehci-hcd driver. I don't remember where those files are located and I don't know what the data means, but maybe the driver's maintainer can tell you and interpret the contents. If an URB has been submitted but isn't on the schedule, perhaps it will show up there. Is it possible for you to test the camera with a different computer? Does the hardware permit you to run at at USB full speed instead of high speed? If it does, what happens if you rmmod ehci-hcd? Alan Stern ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
