Recent pcm/ac97 commit breaks all the glass in my house

[John Baldwin]

On 23-Apr-2003 Daniel Eischen wrote:
> I get a terrible feedback from pcm immediately upon booting and
> probing my sound chip.  It doesn't go away and I have to reboot.
> My system is a Dell 4150 laptop with integrated sound that is
> probed as:
> 
> pcm0: <Intel 82801CA (ICH3)> port 0xdc80-0xdcbf,0xd800-0xd8ff irq 11 at device 31.5 on pci0
> pcm0: <Cirrus Logic CS4205 AC97 Codec>

I get the same exact problem on my Dell 5000e.  It is quite annoying.
The sound device even seems to be picking up sounds such as keypresses.
I thought my laptop was physically broken when it first happened. :(

> Reverting to revision 1.39 of dev/sound/pcm/ac97.c fixes the problem.

I'll try this in a bit.  I can verify that doing 'mixer vol 0' does
solve the problem for me.  I tried turning all the other mixers off
first but only muting the master volume fixed the problem.

Ok, it seems that the following change is sufficient:

+#if 0
        /* use igain for the mic 20dB boost */
        [SOUND_MIXER_IGAIN]     = { -AC97_MIX_MIC,      1, 6, 0, 0, 0, 1, 1 },
+#endif

I tried playing with mixer igain (which defaulted to 0), but turning
it up just made things a lot worse.

-- 

John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/