Fernando Pablo Lopez-Lezcano wrote: > > snd-usb-midi should be loaded when you try to access the sequencer device. > > "aconnect -o" or trying to play/record something usually does the job. > > "aconnect -o" does it, starting Muse (which uses alsa native > midi) does it but starting Pd (which uses the OSS emulation > midi raw devices) does not load the snd-usb-midi modules. Is > there a reason why the load is delayed?
ALSA loads sequencer drivers lazily because most users only want to play .wav and MP3^H^H^HOgg files and thus do not have to suffer the overhead of the sequencer which is quite big. In most cases, the sequencer would have been loaded because of the existence of the OPL3 FM synthesize which nodody wants to use anyway. > Or maybe I need to put something in /etc/modules.conf to > accomplish this? I think add-above/below could do what you want. Please have a look at the manpage. > > Please compare /proc/bus/usb/devices before and after. It really should > > not be possible to replace a driver already connected to the device. > > This is what it shows (diffs from previous state): > > - first load all alsa drivers, including snd-usb-audio and snd-usb-midi > [baseline] > > - then unload all alsa drivers: > > -I: If#= 0 Alt= 0 #EPs= 0 Cls=01(audio) Sub=01 Prot=00 Driver=snd-usb-audio > -I: If#= 1 Alt= 0 #EPs= 2 Cls=01(audio) Sub=03 Prot=00 Driver=snd-usb-audio > +I: If#= 0 Alt= 0 #EPs= 0 Cls=01(audio) Sub=01 Prot=00 Driver=(none) > +I: If#= 1 Alt= 0 #EPs= 2 Cls=01(audio) Sub=03 Prot=00 Driver=(none) Interface 0 is the AudioControl interface. Its purpose is to list all AudioStreaming and MIDIStreaming interfaces of the device. In this case, if0 has a pointer to MIDI if1 (see lsusb for the boring details), and snd-usb-audio grabs both interfaces. > - just load the alsa audio drivers (alsasound startup script) > [no changes] > > - load the "audio" module > [no changes] audio looks at the control interface, doesn't find any AudioStreaming interfaces, and therefore doesn't do anything. > - load the "usb-midi" module > > I: If#= 0 Alt= 0 #EPs= 0 Cls=01(audio) Sub=01 Prot=00 Driver=(none) > -I: If#= 1 Alt= 0 #EPs= 2 Cls=01(audio) Sub=03 Prot=00 Driver=(none) > +I: If#= 1 Alt= 0 #EPs= 2 Cls=01(audio) Sub=03 Prot=00 Driver=midi usb-midi does _not_ look at the control interface, it simply grabs all MIDIStreaming interfaces. (The old snd-usb-midi driver from 0.9.0rc3 did the same.) > - load snd-usb-audio, snd-usb-midi > > -I: If#= 0 Alt= 0 #EPs= 0 Cls=01(audio) Sub=01 Prot=00 Driver=(none) > -I: If#= 1 Alt= 0 #EPs= 2 Cls=01(audio) Sub=03 Prot=00 Driver=midi > +I: If#= 0 Alt= 0 #EPs= 0 Cls=01(audio) Sub=01 Prot=00 Driver=snd-usb-audio > +I: If#= 1 Alt= 0 #EPs= 2 Cls=01(audio) Sub=03 Prot=00 Driver=snd-usb-audio > > So it appears things are being replaced when they should not be. Yes. Interface 0 doesn't have a driver, so the Linux kernel tries to load snd-usb-audio for it. snd-usb-audio then looks at the list of streaming interfaces (see above) and grabs interface 1 without checking if this interface is used by another driver. This is a bug in snd-usb-audio. Regards, Clemens ------------------------------------------------------- This SF.NET email is sponsored by: AMD - Your access to the experts on Hammer Technology! Open Source & Linux Developers, register now for the AMD Developer Symposium. Code: EX8664 http://www.developwithamd.com/developerlab _______________________________________________ Alsa-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-devel
