[alsa-devel] [PATCH] ALSA: hda - Set TLV_DB_SCALE_MUTE bit for cx5051 vmaster

[Raymond Yau]

> Conexnat HD-audio driver has a workaround for cx5051 (aka CX20561)
> chip to add fake mute controls to each amp (commit 3868137e).  This
> implies the minimum-as-mute TLV bit in TLV for each corresponding
> control.  Meanwhile we build the virtual master from these, but the
> TLV bit is missing, even though the slaves have it.
>
> This patch simply adds the missing TLV_DB_SCALE_MUTE bit for vmaster,
> as already done in patch_sigmatel.c.
>
> Signed-off-by: Takashi Iwai <tiwai at suse.de>
> ---
>  sound/pci/hda/patch_conexant.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/sound/pci/hda/patch_conexant.c
b/sound/pci/hda/patch_conexant.c
> index 7627a69ca6d7..6f2fa838b635 100644
> --- a/sound/pci/hda/patch_conexant.c
> +++ b/sound/pci/hda/patch_conexant.c
> @@ -26,6 +26,7 @@
>  #include <linux/module.h>
>  #include <sound/core.h>
>  #include <sound/jack.h>
> +#include <sound/tlv.h>
>
>  #include "hda_codec.h"
>  #include "hda_local.h"
> @@ -859,6 +860,11 @@ static int patch_conexant_auto(struct hda_codec
*codec)
>         if (err < 0)
>                 goto error;
>
> +       if (codec->vendor_id == 0x14f15051) {
> +               /* minimum value is actually mute */
> +               spec->gen.vmaster_tlv[3] |= TLV_DB_SCALE_MUTE;
> +       }
> +
>         codec->patch_ops = cx_auto_patch_ops;
>
>         /* Some laptops with Conexant chips show stalls in S3 resume,
> --

Does this mean that when there is no hardware mute switch, the driver
create a fake one using mindB of volume as mute ?

But this mean that the volume control and mute are not independent anymore,
just like those pulseaudio volume controls,  volume always change to zero
after mute and unmute