[alsa-devel] [PATCH 6/6] ALSA: hda/ca0132: Fix DMic data rate for Alienware M17x R4

[Connor McAdams]

In my experience, the Dmic is always set to have the voice focus
effect enabled on the Chromebook. The reason it drops the sample rate
is to ease the load on the DSP. On the Recon3Di and the Sound Blaster
Z, if effects are enabled, it drops to 16khz when effects in general
are enabled. I don't work for Creative so I have no clue about the
actual details, but I do know if input effects are on on R3Di or SBZ,
the card becomes laggy and less responsive to commands.

So, it may depend upon the implementation. You could probably figure
out definitively by using my program QemuHDADump to dump the data if
you really wanted to find out for sure what sample rate the mic is set
to by default, and the other parameters. I would be willing to look
through the data dump to help you determine it. Let me know.

On Fri, Jun 15, 2018 at 9:56 PM, Alastair Bridgewater
<alastair.bridgewater at gmail.com> wrote:
> The commentary says to use various parameters, and lays out what
> the mapping is...  The code used a 32KHz rate when the comment
> says that it needs to use a 48KHz rate.  And this has been the
> case since day one.
>
> On the Alienware M17x R4, the DMic used to have exceptionally quiet
> pickup and a lot of noise.  Changing the data rate fixes both of
> these issues.
>
> Searching the kernel bug tracker for ca0132-related issues shows no
> mention of this being an issue for other hardware, and I have no
> other hardware to test with, so a quirk is used to limit the effect
> to just the M17x R4.
>
> Signed-off-by: Alastair Bridgewater <alastair.bridgewater at gmail.com>
>
> diff --git a/sound/pci/hda/patch_ca0132.c b/sound/pci/hda/patch_ca0132.c
> index cef22c60d7ee..614f69407c9f 100644
> --- a/sound/pci/hda/patch_ca0132.c
> +++ b/sound/pci/hda/patch_ca0132.c
> @@ -991,6 +991,7 @@ struct ca0132_spec {
>  enum {
>         QUIRK_NONE,
>         QUIRK_ALIENWARE,
> +       QUIRK_ALIENWARE_M17XR4,
>         QUIRK_SBZ,
>         QUIRK_R3DI,
>  };
> @@ -1040,6 +1041,7 @@ static const struct hda_pintbl r3di_pincfgs[] = {
>  };
>
>  static const struct snd_pci_quirk ca0132_quirks[] = {
> +       SND_PCI_QUIRK(0x1028, 0x057b, "Alienware M17x R4", QUIRK_ALIENWARE_M17XR4),
>         SND_PCI_QUIRK(0x1028, 0x0685, "Alienware 15 2015", QUIRK_ALIENWARE),
>         SND_PCI_QUIRK(0x1028, 0x0688, "Alienware 17 2015", QUIRK_ALIENWARE),
>         SND_PCI_QUIRK(0x1028, 0x0708, "Alienware 15 R2 2016", QUIRK_ALIENWARE),
> @@ -6130,7 +6132,10 @@ static void ca0132_init_dmic(struct hda_codec *codec)
>          * Bit   6: set to select Data2, clear for Data1
>          * Bit   7: set to enable DMic, clear for AMic
>          */
> -       val = 0x23;
> +       if (spec->quirk == QUIRK_ALIENWARE_M17XR4)
> +               val = 0x33;
> +       else
> +               val = 0x23;
>         /* keep a copy of dmic ctl val for enable/disable dmic purpuse */
>         spec->dmic_ctl = val;
>         snd_hda_codec_write(codec, spec->input_pins[0], 0,
> --
> 2.16.1
>
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