Hi Alex, Am Samstag, 16. Oktober 2010, 15:58:40 schrieb Alex Lee: > On Sat, 2010-10-16 at 12:25 +0200, Julian Scheel wrote: > > Thanks, I implemented them the way same you did. So for get_min/max/cur I > > always return 48kHz and set_cur simply does nothing. > > Now playback in general works again. But still the rate feedback seems to > > have no impact on the data-rate. Also the frequency value shown in > > proc-interface is unchanged. When rate feedback works, it would probably > > be slightly different than 48.000kHz?! > > OK, you are getting close :-) I hope so (c: > One debug technique we have been using is to do a USB wire dump, using > something like wireshark. This way you can see exactly what goes on > between the PC host and the device. Yes, using wireshark is a good idea indeed. And it immediately turns out what the problem is. The device sends ISOCHRONOUS out packets on the feedback endpoint (5, respectively 0x85) - but when I try to send 4 byte, the URB length is always 0. If I only send 3 or less bytes the packets look fine. I thought it might be a bug regarding max packet size in the at91lib and raised it to 5, but still only 3 bytes can be send. Any clues what might cause such an error? > The other technique is to build a special debug kernel to have copious > debug messages. > > You might want to double check on the EP limitations. Is the feedback > EP capable of ISO transfer? Are you able to use 4 bytes as the max EP > size? Is the EP double buffered (required for ISO transfers)? With the > wireshark dump you will be able to see exactly what is transferred as > the feedback rate. Yep, using endpoint 5, which is able to do ISO and has dual bank. It allows up to 512byte packet size. > Also, the Max EP size of the ISO OUT data EP should only be one sample > frame (ie 4 bytes in your case - 16 bits x stereo) bigger than the > "correct" frame size, ie 192 bytes ====> 196 bytes. Ok, changed that. > I looked through your updated USB descriptors and they appear to be > correct. Fine, thanks (c: Regards, Julian _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
