[alsa-devel] MTP-AV Bugs

[Takashi Iwai]

At Wed, 11 Feb 2009 14:44:13 +0100,
Holger Dehnhardt wrote:
> 
> 
> Am Mittwoch, 11. Februar 2009 14:26:23 schrieb Takashi Iwai:
> > At Wed, 11 Feb 2009 14:18:59 +0100,
> >
> > Holger Dehnhardt wrote:
> > > Dear Takashi,
> > >
> > > thank you for your quick response!
> > > See my inline comments.
> > >
> > > Am Mittwoch, 11. Februar 2009 13:08:22 schrieb Takashi Iwai:
> > > > At Tue, 10 Feb 2009 21:54:32 +0100,
> > > >
> > > > Holger Dehnhardt wrote:
> > > > > After some time I found the following bug:
> > > > >
> > > > > static void snd_mtpav_inmidi_h(struct mtpav *mcrd, u8 inbyte)
> > > > > {
> > > > >         if (inbyte >= 0xf8) {
> > > > >                 /* real-time midi code */
> > > > > -->                snd_mtpav_inmidi_process(mcrd, inbyte);
> > > > > 	//here the inmidiport is not translated to the prtnumber, so
> > > > > 	// snd_mtpav_inmidi_process the port with an index of some 80000
> > > > > 	// in the ports array of the mtpav struct was called
> > > >
> > > > Good catch.  I think the patch below should fix the problem
> >
> > Did you try my patch?
> 
> Sorry, Takashi, I'm still at work. I will try your path tonight when I'm home 
> and my children are in bed;-)

Heh, you can teach your children driver programming :)


> > > > > The following change made the driver work:
> > > > > static void snd_mtpav_inmidi_h(struct mtpav *mcrd, u8 inbyte)
> > > > > {
> > > > >         if (inbyte >= 0xf8) {
> > > > >                 /* real-time midi code */
> > > > > 		mcrd->inmidiport = translate_hwport_to_subdevice(mcrd, inbyte);
> > > >
> > > > This isn't correct since inbyte is supposed to be under 0x13.
> > >
> > > Sorry, I don't understand what you mean: inbyte should always be lower
> > > than 0x13 or is the real time midi code always lower then 0x13?
> >
> > I meant that the data passed to translate_hwport_to_subdevice() is
> > supposed to be <= 0x13.  In that code path, inbyte is >= 0xf8, thus
> > you pass an invalid data.
> >
> > > > > After that I realised, that with the recent driver - even without my
> > > > > change - playing midi files din not work anymore.
> > > > > Only the first midi event was sent to the interface, everything else
> > > > > was dropped somewhere.
> > > > >
> > > > > So a diff between the last workin version and the recent version
> > > > > showed only one change:
> > > >
> > > > What was the last working version exactly?
> > >
> > > 1.0.18 (from the debian experimental repository)
> >
> > Weird.  There is really no essential change since that.
> > Are you sure that you just copied 1.0.18 mtpav.c fixes the problem?
> 
> The only change I did was to change snd_card_create(...) back to 
> snd_card_new(..) in the recent driver (1.0.19) to get the MIDI OUT working 
> again.
> 
> After applying your patch I will go into this again.

Hm, then I'm really puzzled.  Anyway, it'd be helpful if you can
double-check it.


thanks,

Takashi