On Tue, Jun 05, 2007 at 03:26:07PM -0500, James Graves wrote: > > Hello all, > > We're seeing a strange problem when writing commands to a Sierra > Wireless USB modem. It is a USB 1.1 device. > > We're sending some commands over the control channel for the modem. > Almost everything works fine.
How are you sending these commands? The current in-kernel driver doesn't support this from what I can see, right? > However, when sending commands larger than 64 bytes, the rest of the > data (which was a part of that write) is corrupted, which we've seen > using a USB sniffer. Corrupted where, coming from the host to the device? Are you sure you aren't just forgetting to "encode" your data properly as the device specs show that you need to do so? I can dig up the relevant reference if you need it. > We have modified the userspace application so that it writes only up to > 64 bytes at a time, sleeps a little, and then writes more. This works > fine. This sounds odd, what endpoint pair are you sending to? > The strange part is that we've seen no issues with using the PPPD > application to connect to the Internet using the Sierra Wireless modem. > And it has got to be writing more than 64 bytes at a time, though that > is to a different device file (and therefore a different bulk endpoint). Which device is this? > The even stranger part is that the sierra.c driver doesn't make any > significant distinctions between the different USB bulk endpoints. They > are mapped to their individual /dev/ttyUSBx device files, and that's it. > They all have the same number of URBs, and the code paths for all the > bulk endpoints are the same. Yeah, that's why I'm confused :) > So it isn't at all clear to me why everything would be fine with one > endpoint, and not with another. > > Unless the system is negotiating different transfer parameters for the > different endpoints (which aren't _exactly_ identical in hardware)... The system doesn't do anything different, you have the code to prove that. thanks, greg k-h ------------------------------------------------------------------------- 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
