[alsa-devel] [PATCH 3/5] Sound: SOC: TAS571x: implemented digital mute

[Petr Kulhavy]

On 14 March 2016 at 20:39, Kevin Cernekee <cernekee at chromium.org> wrote:
> On Thu, Mar 10, 2016 at 3:22 AM, Petr Kulhavy <petr at barix.com> wrote:
>> The driver did not have a mute function. The amplifier was brought out of
>> shutdown mode (hard-mute) once for ever in probe(), which was causing
>> clicks and pops when altering the I2C register configuration later.
>>
>> This adds the digital_mute() function. The amplifier unmute in probe()
>> was removed.
>>
>> Signed-off-by: Petr Kulhavy <petr at barix.com>
>> Tested-by: Petr Kulhavy <petr at barix.com>
>> ---
>>  sound/soc/codecs/tas571x.c | 22 ++++++++++++++++++----
>>  1 file changed, 18 insertions(+), 4 deletions(-)
>>
>> diff --git a/sound/soc/codecs/tas571x.c b/sound/soc/codecs/tas571x.c
>> index 2a63069..431dffa 100644
>> --- a/sound/soc/codecs/tas571x.c
>> +++ b/sound/soc/codecs/tas571x.c
>> @@ -171,6 +171,23 @@ static int tas571x_hw_params(struct snd_pcm_substream *substream,
>>                                   TAS571X_SDI_FMT_MASK, val);
>>  }
>>
>> +static int tas571x_mute(struct snd_soc_dai *dai, int mute)
>> +{
>> +       struct snd_soc_codec *codec = dai->codec;
>> +       u8 sysctl2;
>> +       int ret;
>> +
>> +       sysctl2 = mute ? TAS571X_SYS_CTRL_2_SDN_MASK : 0;
>> +
>> +       ret = snd_soc_update_bits(codec,
>> +                           TAS571X_SYS_CTRL_2_REG,
>> +                    TAS571X_SYS_CTRL_2_SDN_MASK,
>> +                    sysctl2);
>> +       usleep_range(1000, 2000);
>> +
>> +       return ret;
>> +}
>> +
>>  static int tas571x_set_bias_level(struct snd_soc_codec *codec,
>>                                   enum snd_soc_bias_level level)
>>  {
>> @@ -218,6 +235,7 @@ static int tas571x_set_bias_level(struct snd_soc_codec *codec,
>>  static const struct snd_soc_dai_ops tas571x_dai_ops = {
>>         .set_fmt        = tas571x_set_dai_fmt,
>>         .hw_params      = tas571x_hw_params,
>> +       .digital_mute   = tas571x_mute,
>>  };
>
> Hi Petr,
>
> It is good to see that this driver is getting some use. :-)
>
> An earlier iteration of the code implemented digital_mute, although it
> used a different register:
>
> +        return regmap_update_bits(priv->regmap,
> +                                 TAS571X_SOFT_MUTE_REG,
> +                                 TAS571X_SOFT_MUTE_CH_MASK,
> +                                 mute ? TAS571X_SOFT_MUTE_CH_MASK : 0);
>
> This was removed here: https://chromium-review.googlesource.com/#/c/265878/
>
> Are you able to test the modified code on 5711 and 5717 (or 5719)?

Hi Kevin,

unfortunately I have only a board with TAS5721. But according to their
datasheets all three types of amplifiers (11, 17 and 21) use the same
bit 6 in register 0x05 for hard mute (all channels shut down). On
TAS5721 it works well and using oscilloscope one can even see that the
PWM is switched off.

The patch you are referring to is not correct since it mutes the input
but not the power stage.
Another issue is that the channel mute is exported as a widget and
therefore conflicting with what the user set.
The problem I was facing is that reconfiguration of the PWMs and/or
output mapping (in the "soundcard" driver) was causing nasty pops in
the speaker. Therefore the PWM shutdown (hard mute) is needed.

Regards
Petr