[alsa-devel] [PATCH] ALSA: hda - Disable AA-loopback on ALC668

[Gabriele Mazzotta]

On Wednesday 14 May 2014 16:31:13, Gabriele Mazzotta <gabriele.mzt at gmail.com> wrote:
> Disable the AA-loopback path to get rid of the constant white noise
> that can be heard when headphones are used.
> 
> This patch was tested only on a Dell XPS13 9333.
> 
> Fix based on d2e92709e88d ("ALSA: hda - Disable AA-loopback on ALC283
> Chromebook").
> 
> Signed-off-by: Gabriele Mazzotta <gabriele.mzt at gmail.com>
> ---
>  sound/pci/hda/patch_realtek.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/sound/pci/hda/patch_realtek.c b/sound/pci/hda/patch_realtek.c
> index 5f7c765..21c94e4 100644
> --- a/sound/pci/hda/patch_realtek.c
> +++ b/sound/pci/hda/patch_realtek.c
> @@ -5690,6 +5690,13 @@ static int patch_alc662(struct hda_codec *codec)
>  	if (has_cdefine_beep(codec))
>  		spec->gen.beep_nid = 0x01;
>  
> +	switch (codec->vendor_id) {
> +	case 0x10ec0668:
> +		/* Disable AA-loopback as it causes white noise */
> +		spec->gen.mixer_nid = 0;
> +		break;
> +	}
> +
>  	if ((alc_get_coef0(codec) & (1 << 14)) &&
>  	    codec->bus->pci && codec->bus->pci->subsystem_vendor == 0x1025 &&
>  	    spec->cdefine.platform_type == 1) {
> 
I'm sorry, I was wrong. This patch does not help. I'm still trying to
understand what temporarily fixed the problem, I was quite sure this patch did
it, but all of the sudden the noise came back. I'm still trying to find the
real cause, but I doubt I'll succeed.

Regards,
Gabriele