[alsa-devel] crash/reboot with rawmidi on ice1712 dual opteron

[Takashi Iwai]

At Tue, 24 Apr 2007 16:53:20 +0200,
Florian wrote:
> 
> > When the hang-up occurs at the first write, it must be in 
> > snd_mpu401_uart_cmd().  At the very beginning, it calls 
> > mpu->write(mpu, 0x00, MPU401D(mpu)); Try to comment out this and
> > see what happens.
> 
> I had tried that - I think that I just commented out the reset
> command.

The reset command contains a series of writes.  The write access (zero
to 0x304c) is the very first part, and this isn't always necessary.
For example, trident doesn't like this sequence.  So, just commenting
out this write should be fairly harmless to the later behavior.

So, commenting only the first zero write is worth to try (if you
didn't do yet).


> It would not crash or reboot, but it did not haver
> functionality either.
 
> > Do I understand correctly that this bug happens when you open a 
> > rawmidi device for read, e.g. % cat /dev/snd/midiC0D0 > /dev/null
> > 
> yes. I usually used
> amidi -p hw:0 -d
> 
> > Perhaps an easiest but foolishest way to trace this is to put
> > printk at each io-port access and any other important points, and
> > give some sleep at each point, then watch the kernel message.
> > You can get rid of spin_lock_*() around that, just for testing.
> 
> I've done this until I traced it to the first outb() call, i.e. the
> initialization mentioned above. The first outb() will cause the reboot.

And this causes an immediate reboot, not panic or oops, right?
You shouldn't do this kind of debug on X but on VGA console, BTW.


Takashi