linux-kernel - Re: hda-intel: azx_get_response timeout, switching to polling mode: last cmd=0x01db0000

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Message-ID: <20120123102327.GP30898@machine.or.cz>
Date:	Mon, 23 Jan 2012 11:23:28 +0100
From:	Petr Baudis <pasky@....cz>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	Jonathan Nieder <jrnieder@...il.com>, alsa-devel@...a-project.org,
	linux-kernel@...r.kernel.org
Subject: Re: hda-intel: azx_get_response timeout, switching to polling mode:
 last cmd=0x01db0000

On Mon, Jan 23, 2012 at 10:51:43AM +0100, Takashi Iwai wrote:
> At Mon, 23 Jan 2012 10:46:30 +0100,
> Petr Baudis wrote:
> > 
> > On Mon, Jan 23, 2012 at 10:18:24AM +0100, Takashi Iwai wrote:
> > > Thanks.  Switching to the polling mode is really harmless.
> > > So, basically you can ignore these messages.  I can change it only as a
> > > debug message.
> > > 
> > > OTOH, if the switching to single_cmd mode happens, this is a serious
> > > problem.  But, as far as I see in alsa-info.sh output, it didn't
> > > happen.
> > 
> > Ok, then the bug is in handling of polling mode in this particular chip.
> > After such switch to polling mode, applications will get stuck on
> > releasing the soundcard.
> 
> What do you mean "releasing the soundcard"?  Closing the PCM stream,
> or unloading the module, or at shutdown?

  Closing the PCM stream - see strace snippet in the original post.

> > Another symptom I forgot to describe is that
> > the last ~100ms of output will keep repeating when I pause/stop
> > playback, one has to mute the volume to get rid of this. Again, this
> > starts happenning only sometimes after the switch to polling mode,
> > but then keeps happenning fairly consistently.
> 
> Hm, this sounds like some interrupt issue, then.  After all, switching
> to the polling-mode happens because the expected interrupt didn't
> arrive in time.  If a similar problem happens in the PCM stream, too,
> it might be some other generic interrupt problem.

  The soundcard used to work on much older kernel versions. The only
issue I had with this chipset were general (sound, network, ...) DMA
problems from 4GiB+ memory areas after I upgraded my memory, but that
got fixed in newer kernel version. The soundcard uses unique IRQs:

	           CPU0       CPU1
	 43:         24       7290   PCI-MSI-edge      snd_hda_intel
	 44:          1         60   PCI-MSI-edge      snd_hda_intel

  Any clues on how I can debug this?

-- 
				Petr "Pasky" Baudis
	The goal of Computer Science is to build something that will
	last at least until we've finished building it.
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