[alsa-devel] VT1708 clicks & pops

[Takashi Iwai]

At Tue, 27 Sep 2011 17:45:32 -0400,
Forest Bond wrote:
> 
> Hi Takashi,
> 
> On Tue, Sep 27, 2011 at 02:57:16PM +0200, Takashi Iwai wrote:
> > At Wed, 21 Sep 2011 13:55:53 -0400, Forest Bond wrote:
> > > On Wed, Sep 21, 2011 at 04:43:15PM +0200, Takashi Iwai wrote:
> > > > At Wed, 21 Sep 2011 10:35:10 -0400, Forest Bond wrote:
> > > > > On Wed, Sep 21, 2011 at 10:39:44AM +0200, Takashi Iwai wrote:
> > > > > > At Tue, 20 Sep 2011 15:05:34 -0400, Forest Bond wrote:
> > > > > > > On Tue, Sep 20, 2011 at 09:22:23AM +0200, Takashi Iwai wrote:
> > > > > > > > At Mon, 19 Sep 2011 19:14:13 -0400, Forest Bond wrote:
> > > > > > > > > On Fri, Sep 16, 2011 at 04:36:01PM -0400, Forest Bond wrote:
> > > > > > > > > > I have two boards with a VT1708:
> > > > > > > > > > 
> > > > > > > > > > * VIA EPIA EX15000G
> > > > > > > > > > * VIA VB8002
> > > > > > > > > > 
> > > > > > > > > > I'm using VLC to play audio via PulseAudio to the analog outputs.  The VB8002
> > > > > > > > > > sounds great, but the EX15000G has random pops and clicks in the output.  Both
> > > > > > > > > > machines are running exactly the same configuration (they are using the same
> > > > > > > > > > pre-built OS image).
> > > > > > > The crackling with PCM volume set to 0 persists with tsched=0.
> > > 
> > > [...]
> > > 
> > > > > > Hrm, which PA version are you using?  I remember vaguely a buggy PA
> > > > > > SIMD operations in some old PA versions.
> > > > > 
> > > > > 1:0.9.22+stable-queue-24-g67d18-0ubuntu3 from Ubuntu Lucid.
> > > > > 
> > > > > > Also, when you mute the mixer (nor the PA's mixer), e.g. via
> > > > > > "alsamixer -c0", the noise goes away, right?
> > > > > 
> > > > > I do not use the PA mixer.  The noise is present with ALSA's PCM control set to
> > > > > zero (-51dB).  If I move the PCM control up one tick (to -50.8dB) the noise goes
> > > > > away.
> > > > 
> > > > OK, then it's an issue in the sound driver.
> > > > Could you give alsa-info.sh outputs both mute-with-noise and without
> > > > noise for comparison?
> > > 
> > > I guess we can ignore this one for now.  I do not have this problem using a
> > > recent alsa-driver snapshot.  The PCM control does not go below -40.25dB with
> > > this version.  It's possible the new driver simply doesn't allow the control to
> > > be set to a problematic value.
> > > 
> > > I will note, however, that the master control with the snapshot has a minimum
> > > value of 0dB and a maximum of 6.75dB,
> > 
> > That's odd.
> > 
> > > and that the audio is barely audible at
> > > 0dB.  I have to crank the master control all the way up to get the same volume
> > > as the old driver set to 0dB.  Maybe I can come up with a fix for this.
> > 
> > For debugging, I'd need anyway the alsa-info.sh output from the latest
> > alsa-driver snapshot.
> 
> Okay, here you go:
> 
>   http://www.alsa-project.org/db/?f=8f3da35bd1b615d199f8e71df8b012fbdf5ff690

This is the working device, right?

> > Also, I'm working now on non-snooping mode support, and this might
> > help for fixing some problems like yours.  Could you try the patch
> > below (with the snapshot version)?
> 
> Unfortunately, this doesn't seem to help.
> 
> Given the similarities between the working and non-working boards, I was
> wondering if the BIOS is setting up the chips differently and that is the
> immediate cause of the problems.  In particular:
> 
> * There is no set_widgets_power_state function for this chip.  If the BIOS
>   enables some power management function on one board but not the other and the
>   driver has no way to disable it, could that cause an issue like this one?

No, as default the driver powers up all widgets and power down all
again at power-saving.  The VIA codec driver has an advanced
implementation to turn off a few unused widgets even in power-up.
And this feature is missing in VT1708.  So, it doesn't mean that the
driver has no power control.  It has.

> * I see that the VB8002 has "N/A" listed for "Pin Default" for several
>   "Pin Complex" nodes where the EX15000G has "Jack".  Is it possible the
>   EX15000G has some nodes configured as AC_JACK_PORT_COMPLEX that should be
>   configured as AC_JACK_PORT_NONE?

I don't know.  You need to check whether the pins are really correctly
set up.  For example, most of jacks have the detection capability.
Then plug/unplug each jack and check the pin-detection e.g. with
hda-verb program.

> It should be clear that I do not have a very good understanding of the HDA spec.
> I'm assuming the BIOS is responsible for configuring the chip as I've described
> above.  Do any of those problems sound possible to you?  If so, are there ways
> to work around them in the driver?

Yes, pins can be easily overridden via sysfs or patch option.
See Documentation/sound/alsa/HD-Audio.txt.


Takashi