Hello, I have some problems with data transfers to an INT out endpoint. Maybe someone can help me....
I am running Linux 2.4.17 and usb-uhci. The target device wants to get an INT out transfer every 2 ms, with a maximum paket size of 64 Bytes, and the actual paket size taylored to the amount of free bytes in the devices' input buffer. So I have set up a periodic INT transfer, but was not able to modify the transfer size from inside the completion handler. IMO this asymmetric behavior of the INT transfer is a design weakness. Maybe it should be addressed in 2.5.x ? So I have tried to use one-shot-INT transfers. The first thing I have noticed is that is is not possible to submit the next transfer from the completion handler of the previous one. So, inside the completion handler, I have set a flag and submit the next transfer later. IMO this is also a design weakness. For a one-shot-transfer, the completion handler says: "I'm done with it", and why should I don't do the next transfer? Maybe this is also an issue for 2.5.x? I remember there was a thread for this topic at linux-usb-devel... I wonder if the design with setting a flag in the completion handler and submitting the next paket later is race-free on SMP systems, but this is not my problem today... The submitting of the next urb is done inside the completion handler of another endpoint. Note that I don't unlink the INT urbs. I think that one-shot-INTs are doing the unlink automatic. Right? My problem with this approach is: only the *first* INT urb is actually transfering data to the device. All the following urbs are executing fine (no errors, no urb->status != 0), but the usb device one the other side don't get any data! (I know that the same device is running fine on MS Windows). I have no USB analyser here at home, and I am on holiday now... It is clear that I have to have a closer look at the problem... but in the meantime: does someone has an insight of what is going on? Which is the best solution to serve the device? Did I do something wrong? best regards Wolfgang -- "We're back to the times when men were men and wrote their own device drivers." -Linus Torvalds- _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
