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

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Message-ID: <6278d2220808141210p3c612feen6fe779bc84a4ae78@mail.gmail.com>
Date:	Thu, 14 Aug 2008 20:10:03 +0100
From:	"Daniel J Blueman" <daniel.blueman@...il.com>
To:	"Takashi Iwai" <tiwai@...e.de>
Cc:	"Vegard Nossum" <vegard.nossum@...il.com>,
	"Romano Giannetti" <romano@....icai.upcomillas.es>,
	"Linux Kernel" <linux-kernel@...r.kernel.org>
Subject: Re: ALC883 recording troubles...

Hi Takashi,

I am still finding this recording +ve saturation on my ALC883 Intel
HDA sound device with 2.6.27-rc3 (ie ALSA 1.0.17 drivers) and ALSA
1.0.16-1 libraries on Ubuntu Intrepid.

The previous workaround still 'gets us out of jail':

# ./hda-verb /dev/snd/hwC0D0 0x23 SET_AMP_GAIN_MUTE 0x7180
nid = 0x23, verb = 0x300, param = 0x7180
value = 0x0

Note, we see this message "hda_codec: Unknown model for ALC883, trying
auto-probe from BIOS..." as before on this Asus P5E-VM HDMI
motherboard with current BIOS.

How can we improve the situation, as out the box, the front/rear mic
inputs are (still) useless?

Many thanks,
  Daniel

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:
>> 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.
-- 
Daniel J Blueman
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