linux-kernel - Re: ALC883 recording troubles...

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Date:	Sat, 28 Jun 2008 13:29:32 +0100
From:	"Daniel J Blueman" <daniel.blueman@...il.com>
To:	"Vegard Nossum" <vegard.nossum@...il.com>
Cc:	"Takashi Iwai" <tiwai@...e.de>,
	"Romano Giannetti" <romano@....icai.upcomillas.es>,
	"Linux Kernel" <linux-kernel@...r.kernel.org>
Subject: Re: ALC883 recording troubles...

On Sat, Jun 28, 2008 at 11:29 AM, Daniel J Blueman
<daniel.blueman@...il.com> wrote:
> On Sat, Jun 28, 2008 at 11:11 AM, Vegard Nossum <vegard.nossum@...il.com> wrote:
>> (removed linux-kernel from Cc)
>>
>> On Sat, Jun 28, 2008 at 2:05 AM, Daniel J Blueman
>> <daniel.blueman@...il.com> wrote:
>>> As the mic is working fine, but with this variable DC offset, it felt
>>> like something needed tweaking in the mixer (summation) node. I
>>> understand more about the node connectivity now, and found muting the
>>> front mic mixer input and setting LR gain to 0 at mixer node 23h
>>> addresses the issue:
>>>
>>> (from page 42 at ftp://66.104.77.130/pc/audio/ALC883_DataSheet_1.3.pdf)
>>>
>>> # ./hda-verb /dev/snd/hwC0D0 0x23 SET_AMP_GAIN_MUTE 0x7180
>>
>> Are you saying that this fixes the problem completely for you?
>
> Yes, this addresses the problem squarely. The front mix mixer input is
> adding this offset, looks like they have a capacitor between a
> reference voltage and the pin or something, so it floats up.
>
>>> Vegard - your HD bus enumeration looks similar and I'd bet the vendor
>>> followed the same Realtek application note, so can you give this a
>>> shot too? If not, try mixer node 20h.
>>
>> I agree. Thanks for the link, I found ALC268 now as well, and I am
>> experimenting...
>>
>> I think 23h is [in]correct -- this is the one with caps f00040h for me too.
>>
>> But neither of them had any effect at all.
>
> OK, I'll take another look at the debug output you posted; I forgot
> you aren't using the ALC883.

Using your dumped config and
ftp://202.65.194.211/pc/audio/ALC268_DataSheet_1.3.pdf page 42, your
front mic pin complex is at node 19h; the mixers connecting to it are
at nodes 0Bh, 22h and 23h, all at the second input index, so one of
these should work:

# ./hda-verb /dev/snd/hwC0D0 0x0b SET_AMP_GAIN_MUTE 0x7280
# ./hda-verb /dev/snd/hwC0D0 0x22 SET_AMP_GAIN_MUTE 0x7280
# ./hda-verb /dev/snd/hwC0D0 0x23 SET_AMP_GAIN_MUTE 0x7280

On my ALC883, we need to mute the first input instead, thus 0x7180.
Can you see if the above helps you out?

Thanks,
  Daniel
-- 
Daniel J Blueman
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