linux-kernel - Re: [PATCH] ALSA: hda/realtek - Keep analog bypass muted on ALC892

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Date:	Thu, 09 Aug 2012 09:02:10 +0200
From:	Takashi Iwai <tiwai@...e.de>
To:	Thierry Reding <thierry.reding@...onic-design.de>
Cc:	Jaroslav Kysela <perex@...ex.cz>,
	David Henningsson <david.henningsson@...onical.com>,
	alsa-devel@...a-project.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ALSA: hda/realtek - Keep analog bypass muted on ALC892

At Thu,  9 Aug 2012 08:47:19 +0200,
Thierry Reding wrote:
> 
> Unmuting the analog bypass causes any input to be directly bypassed to
> the outputs, which is usually not expected by the user.
> 
> Signed-off-by: Thierry Reding <thierry.reding@...onic-design.de>
> ---
> Note that this patch could be generalized to include all codec variants
> that have this second channel. As I don't have access to all the data
> sheets I'll leave that decision up to somebody with more hardware
> available.

Hmm, are you really sure that this is exclusive switch between two?
All Realtek codecs with this mixer widget mixes two sources up.
Otherwise it must not be a "mixer" widget at all but it must be a
"selector" widget.

And I haven't received a bug report regarding this although ALC892 is
no new chip and the auto-parser has been enabled for so long time.


thanks,

Takashi


> 
>  sound/pci/hda/patch_realtek.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/sound/pci/hda/patch_realtek.c b/sound/pci/hda/patch_realtek.c
> index 4f81dd4..54d0917 100644
> --- a/sound/pci/hda/patch_realtek.c
> +++ b/sound/pci/hda/patch_realtek.c
> @@ -3752,8 +3752,15 @@ static void alc_auto_set_output_and_unmute(struct hda_codec *codec,
>  	if (nid_has_mute(codec, mix, HDA_INPUT)) {
>  		snd_hda_codec_write(codec, mix, 0, AC_VERB_SET_AMP_GAIN_MUTE,
>  			    AMP_IN_UNMUTE(0));
> -		snd_hda_codec_write(codec, mix, 0, AC_VERB_SET_AMP_GAIN_MUTE,
> -			    AMP_IN_UNMUTE(1));
> +		/*
> +		 * On ALC892, the second entry in the connection list is the
> +		 * analog bypass. Unmuting it will cause any inputs to be
> +		 * directly forwarded to the corresponding outputs.
> +		 */
> +		if (codec->subsystem_id != 0x10ec0892)
> +			snd_hda_codec_write(codec, mix, 0,
> +					    AC_VERB_SET_AMP_GAIN_MUTE,
> +					    AMP_IN_UNMUTE(1));
>  	}
>  	/* initialize volume */
>  	nid = alc_look_for_out_vol_nid(codec, pin, dac);
> -- 
> 1.7.11.4
> 
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