linux-kernel - Re: [PATCH v3 2/3] ASoC: codecs: add new pm4125 audio codec driver

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Message-Id: <DCNMJEP0XW33.1AUMCTJU5UPBY@linaro.org>
Date: Mon, 08 Sep 2025 19:18:35 +0100
From: "Alexey Klimov" <alexey.klimov@...aro.org>
To: "Srinivas Kandagatla" <srinivas.kandagatla@....qualcomm.com>, "Srinivas
 Kandagatla" <srini@...nel.org>
Cc: "Liam Girdwood" <lgirdwood@...il.com>, "Mark Brown"
 <broonie@...nel.org>, "Rob Herring" <robh@...nel.org>, "Krzysztof
 Kozlowski" <krzk+dt@...nel.org>, "Conor Dooley" <conor+dt@...nel.org>,
 "Stephen Boyd" <sboyd@...nel.org>, "Lee Jones" <lee@...nel.org>, "Jaroslav
 Kysela" <perex@...ex.cz>, "Takashi Iwai" <tiwai@...e.com>,
 <linux-arm-msm@...r.kernel.org>, <linux-sound@...r.kernel.org>,
 <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>, "Dmitry
 Baryshkov" <dmitry.baryshkov@....qualcomm.com>,
 <christophe.jaillet@...adoo.fr>
Subject: Re: [PATCH v3 2/3] ASoC: codecs: add new pm4125 audio codec driver

On Mon Sep 8, 2025 at 4:45 PM BST, Srinivas Kandagatla wrote:
> On 9/8/25 4:26 PM, Alexey Klimov wrote:
>> Hi Srini,
>> 
>> On Fri Aug 15, 2025 at 4:36 PM BST, Srinivas Kandagatla wrote:
>
>
>>>> +static int pm4125_codec_enable_rxclk(struct snd_soc_dapm_widget *w, struct snd_kcontrol *kcontrol,
>>>> +				     int event)
>>>> +{
>>>> +	struct snd_soc_component *component = snd_soc_dapm_to_component(w->dapm);
>>>> +
>>>> +	switch (event) {
>>>> +	case SND_SOC_DAPM_PRE_PMU:
>>>>
>>>> +static const struct snd_kcontrol_new pm4125_snd_controls[] = {
>>>> +	SOC_SINGLE_EXT("HPHL_COMP Switch", SND_SOC_NOPM, 0, 1, 0,
>>>
>>>     SOC_SINGLE_EXT("HPHL_COMP Switch", PM4125_COMP_L, 0, 1, 0, ?
>>>
>>>> +		       pm4125_get_compander, pm4125_set_compander),
>>>> +	SOC_SINGLE_EXT("HPHR_COMP Switch", SND_SOC_NOPM, 1, 1, 0,
>>>
>>>        SOC_SINGLE_EXT("HPHR_COMP Switch", PM4125_COMP_R, 1, 1, 0,?
>>>
>>>> +		       pm4125_get_compander, pm4125_set_compander),
>>>
>>> This is same issue in one of the WCD codec, which am going to send fixes
>>> along with my original wcd fixes series.
>> 
>> So this was in other codecs for years, right?
>
> only in wcd937x since it was added.
>
>> 
>>>> +
>>>> +	SOC_SINGLE_TLV("HPHL Volume", PM4125_ANA_HPHPA_L_GAIN, 0, 20, 1,
>>>> +		       line_gain),
>>>> +	SOC_SINGLE_TLV("HPHR Volume", PM4125_ANA_HPHPA_R_GAIN, 0, 20, 1,
>>>> +		       line_gain),
> ...
>                           PM4125_ANA_HPHPA_FSM_DIV_RATIO_MASK,
>>>                                       PM4125_ANA_HPHPA_FSM_DIV_RATIO_68);
>>> @@ -309,8 +307,6 @@ static int pm4125_rx_clk_disable(struct
>>> snd_soc_component *component)
>>>         snd_soc_component_write_field(component,
>>> PM4125_DIG_SWR_CDC_RX_CLK_CTL,
>>>                                       PM4125_DIG_SWR_ANA_RX_CLK_EN_MASK,
>>>                                       PM4125_DIG_SWR_RX_CLK_DISABLE);
>>> -       pm4125_global_mbias_disable(component);
>>> -
>>>         return 0;
>>>  }
>> 
>> This doesn't work. Playback has two issues: 1) volume is very low and probably
>> not adjustable and 2) sound during playback dies after a couple of seconds.
>> 
>> Returning these global_mbias() calls restores the good behaviour.
>
> What is global micbias to do with rx playback? Maybe something is missing.

No idea. Spec that I can see doesn't say a lot about PM4125_ANA_MBIAS_EN register.
Just that these are main biases.

> Which RX path are you testing?
>
> I am testing this with Headphone and Lineout, it works for me.
>
>> 
>> Maybe let's make a widget out of it? In such case I am not sure about
>> routing meaning that I not sure which paths do require mbias enable.
> Not sure why RX would need mic bias?

I am testing lineout that goes into wsa881x amplifier in analog mode (mono).
I use the following amixers:

amixer -c0 cset iface=MIXER,name='RX_CODEC_DMA_RX_0 Audio Mixer MultiMedia1' 1
amixer -c0 cset iface=MIXER,name='RX_MACRO RX0 MUX' 1
amixer -c0 cset iface=MIXER,name='RX INT0 DEM MUX' 1
amixer -c0 cset iface=MIXER,name='RX INT0_1 MIX1 INP0' 'RX0'
#merge two channels together (right channel goes into INT0_1 input1)
amixer -c0 cset iface=MIXER,name='RX INT0_1 MIX1 INP1' 'RX1'
amixer -c0 cset iface=MIXER,name='EAR_RDAC Switch' 0
amixer -c0 cset iface=MIXER,name='HPHL_RDAC Switch' 0
amixer -c0 cset iface=MIXER,name='HPHR_RDAC Switch' 0
amixer -c0 cset iface=MIXER,name='LO_RDAC Switch' 1
amixer -c0 cset iface=MIXER,name='HPHL Switch' 1
amixer -c0 cset iface=MIXER,name='RX_RX0 Digital Volume' 80
amixer -c0 cset iface=MIXER,name='SpkrMono WSA_RDAC' 1

and then aplay. With long .wav files the sound dies after few seconds of playback.
But volume issue is present with any .wav files.

After playing with pm4125_global_mbias_enable(), tt looks like
both PM4125_ANA_MBIAS_EN_GLOBAL and PM4125_ANA_MBIAS_EN_V2I should be enabled to avoid this problem.

Thanks,
Alexey