Loud POP from sound system during module init w/ 2.6.19

Loud POP from sound system during module init w/ 2.6.19

[Ian E. Morgan]

Since upgrading to 2.6.19, two of my boxes (one workstation, one
notebook) started making a very loud (and scary) POP from the sound
system when the alsa modules are loaded. Unloading and reloading the
modules will generate another pop.

I have removed any fiddling of mixer settings during module
load/unload; same results.

I have complied the kernel both with and without
CONFIG_SND_AC97_POWER_SAVE; same results.

The workstation uses snd_emu10k1, the notebook snd_intel8x0, so it's
affecting more than a single driver.

Anybody else seeing this behaviour and know how to stop it?

-- 
Ian E. Morgan
penguin.wrangler@gmail.com

Re: Loud POP from sound system during module init w/ 2.6.19

[Jan Engelhardt]

On Dec 8 2006 13:53, Ian E. Morgan wrote:
>Subject: Loud POP from sound system during module init w/ 2.6.19

What kernel did you have before?

What you see is the same I am experiencing on every boot - when the sound
module is loaded, udev loads the previous volume settings. The volume settings
are normal for me, but I guess the instant jump from 0-70% (for Master) and
0-61% (for PCM) is not taken too heartly by the soundcard.

> Since upgrading to 2.6.19, two of my boxes (one workstation, one
> notebook) started making a very loud (and scary) POP from the sound
> system when the alsa modules are loaded. Unloading and reloading the
> modules will generate another pop.
>
> Anybody else seeing this behaviour and know how to stop it?
>

	-`J'
-- 

Re: Loud POP from sound system during module init w/ 2.6.19

[Ian E. Morgan]

Previous kernel was 2.6.18.3, which did not exhibit the problem. I was
aware of udev setting the mixer at module load time, but I disabled
that and the problem still exists.

-- 
Ian E. Morgan
penguin.wrangler@gmail.com

On 09/12/06, Jan Engelhardt <jengelh@linux01.gwdg.de> wrote:
>
> On Dec 8 2006 13:53, Ian E. Morgan wrote:
> >Subject: Loud POP from sound system during module init w/ 2.6.19
>
> What kernel did you have before?
>
> What you see is the same I am experiencing on every boot - when the sound
> module is loaded, udev loads the previous volume settings. The volume settings
> are normal for me, but I guess the instant jump from 0-70% (for Master) and
> 0-61% (for PCM) is not taken too heartly by the soundcard.
>
> > Since upgrading to 2.6.19, two of my boxes (one workstation, one
> > notebook) started making a very loud (and scary) POP from the sound
> > system when the alsa modules are loaded. Unloading and reloading the
> > modules will generate another pop.
> >
> > Anybody else seeing this behaviour and know how to stop it?

Re: Loud POP from sound system during module init w/ 2.6.19

[Jan Engelhardt]

On Dec 9 2006 08:17, Ian E. Morgan wrote:
>
> Previous kernel was 2.6.18.3, which did not exhibit the problem. I was
> aware of udev setting the mixer at module load time, but I disabled
> that and the problem still exists.

Another reason might be that the sound driver sets the initial volume 
(even before udev can act) to 100%. That's probably Not So Good.
I'd suggest to take a diff between 2.6.18.3's sound tree and the 2.6.19 
one, and see if the driver for your card changed.


	-`J'
-- 

Re: [Alsa-devel] Loud POP from sound system during module init w/ 2.6.19

[Takashi Iwai]

At Fri, 8 Dec 2006 13:53:46 -0500,
Ian E. Morgan wrote:
> 
> Since upgrading to 2.6.19, two of my boxes (one workstation, one
> notebook) started making a very loud (and scary) POP from the sound
> system when the alsa modules are loaded. Unloading and reloading the
> modules will generate another pop.
> 
> I have removed any fiddling of mixer settings during module
> load/unload; same results.
> 
> I have complied the kernel both with and without
> CONFIG_SND_AC97_POWER_SAVE; same results.
> 
> The workstation uses snd_emu10k1, the notebook snd_intel8x0, so it's
> affecting more than a single driver.
> 
> Anybody else seeing this behaviour and know how to stop it?

Hm, interesting.  I thought this should be avoided by disabling
CONFIG_SND_AC97_POWER_SAVE Kconfig.

Do you get the noise at unloading or at loading time?
If it's at unloading time, it's likely in some part of
snd_ac97_powerdown(), handling of AC97_POWERDOWN bits, I guess.


Takashi