linux-kernel - Re: [PATCH 1/6] ASoC: codecs: wsa884x: remove mute_unmute_on

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Message-Id: <DEIUJWR51WIX.43GDTH9RA8UH@linaro.org>
Date: Wed, 26 Nov 2025 18:44:00 +0000
From: "Alexey Klimov" <alexey.klimov@...aro.org>
To: "Jonathan Marek" <jonathan@...ek.ca>, "Srinivas Kandagatla"
 <srinivas.kandagatla@....qualcomm.com>, "Srinivas Kandagatla"
 <srini@...nel.org>
Cc: <linux-arm-msm@...r.kernel.org>, "Liam Girdwood" <lgirdwood@...il.com>,
 "Mark Brown" <broonie@...nel.org>, "Jaroslav Kysela" <perex@...ex.cz>,
 "Takashi Iwai" <tiwai@...e.com>, "Krzysztof Kozlowski" <krzk@...nel.org>,
 "Neil Armstrong" <neil.armstrong@...aro.org>, "open list:QCOM AUDIO (ASoC)
 DRIVERS" <linux-sound@...r.kernel.org>, "open list"
 <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/6] ASoC: codecs: wsa884x: remove
 mute_unmute_on_trigger

On Mon Nov 24, 2025 at 2:55 PM GMT, Jonathan Marek wrote:
> On 11/24/25 9:08 AM, Srinivas Kandagatla wrote:
>> On 11/24/25 6:45 AM, Jonathan Marek wrote:
>>> trigger is atomic (non-schedulable), and soundwire register writes are not
>>> safe to run in an atomic context. (bus is locked with a mutex, and qcom
>>> driver's callback can also sleep if the FIFO is full).
>>>
>> Thanks Jonathan for the patch,
>> 
>> We have nonatomic=1 flag set for all the Qualcomm sound cards, Did you
>> hit any schedule while atomic bug?
>
> Right, I missed that. I'm using a different driver which does not set 
> nonatomic. But this driver to not need nonatomic - 
> mute_unmute_on_trigger is a hack, if there is a timing requirement - 
> then it needs to be explicit, the different timing with this flag is not 
> reliable).
>
>> In-fact this change has helped suppress most of the click and pop noises
>> on laptops, specially with wsa codecs as they accumulate static if the
>> ports are kept open without sending any data.
>> 
>
> 28b0b18d5346 is important to fix the click and pop noises. But the 
> useful part is the rest of the commit, not the mute_unmute_on_trigger 
> flag. As long as the mute_stream() happens while the soundwire stream is 
> enabled (between sdw_enable_stream and sdw_disable_stream), there should 
> be no pop click.
>
> AFAIK the pop/click is because of PDM: zeros (soundwire stream off) 
> represent the minimum (negative maximum) amplitude, and the soundwire 
> stream needs to be enabled to output a zero amplitude (alternating 
> ones/zeros). Turning on the amp while the soundwire stream is not 
> enabled will cause jumps between the minimum and zero amplitude.

>>> -	.mute_unmute_on_trigger = true,

FWIW for wsa881x in analog mode on RB1/RB2 boards I noticed that pop/clicks
sound behaviour is much better when mute_unmute_on_trigger is false.

Although, for wsa881x in soundwire mode the mute_unmute_on_trigger = true
gives decent result of supressing pop/clicks noise on the devices I have.

Maybe it varies from platform to platform and from board to board.

BR,
Alexey