On Mon, Jun 07, 2004 at 05:25:22PM +0800, Roc Wu wrote:
>  --- Clemens Ladisch <[EMAIL PROTECTED]> ģ>
> Roc Wu wrote:
> > > > # ./aplay -t wav -f U8 -r 22050 alarm.wav
> > > > Playing WAVE 'alarm.wav' : Unsigned 8 bit, Rate
> > 22050 Hz, Mono
> > > > ALSA lib
> > pcm_plug.c:727:(snd_pcm_plug_hw_refine_schange)
> > > > Unable to find an usable access for 'default'
> > > > aplay: set_params:832: Sample format non
> > available
> > > >
> > > > And the kernel driver will dump out the message
> > as below:
> > > > Badness in aaci_pcm_close at
> > sound/arm/aaci.c:404
> > 
> > This seems to be a bug in the sound driver.

Actually, I disagree.  It's an ALSA bug.  The warning is created if
the AACI close method is called while the DMA or IO is still running.
If DMA is still running here, we've already freed the DMA buffer, so
we're either reading from or writing to memory we don't own - which is
a major bug.

The question is therefore: why is ALSA trying to shut down and free a
device which still has DMA running?  To be more explicit, why didn't
ALSA call the trigger callback with SNDRV_PCM_TRIGGER_STOP prior to
calling the hw_free or close methods?

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
                 2.6 Serial core


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