Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <2a0aabf5-41a3-cc07-3203-9b0bca6b71aa@linaro.org>
Date:   Fri, 24 Mar 2023 06:44:40 +0000
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.8.0
Subject: Re: [PATCH 3/4] ASoC: codecs: wsa883x: mute/unmute PA in correct
 sequence
Content-Language: en-US
To:     Mark Brown <broonie@kernel.org>
Cc:     perex@perex.cz, tiwai@suse.com, lgirdwood@gmail.com,
        linux-kernel@vger.kernel.org, alsa-devel@alsa-project.org,
        johan+linaro@kernel.org, steev@kali.org,
        dmitry.baryshkov@linaro.org
References: <20230323164403.6654-1-srinivas.kandagatla@linaro.org>
 <20230323164403.6654-4-srinivas.kandagatla@linaro.org>
 <ff3eb88a-6941-4303-a4ba-17cad3842b88@sirena.org.uk>
From:   Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
In-Reply-To: <ff3eb88a-6941-4303-a4ba-17cad3842b88@sirena.org.uk>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk


On 23/03/2023 17:07, Mark Brown wrote:
> On Thu, Mar 23, 2023 at 04:44:02PM +0000, Srinivas Kandagatla wrote:
>> In the current setup the PA is left unmuted even when the
>> Soundwire ports are not started streaming. This can lead to click
>> and pop sounds during start.
>> There is a same issue in the reverse order where in the PA is
>> left unmute even after the data stream is stopped, the time
>> between data stream stopping and port closing is long enough
>> to accumulate DC on the line resulting in Click/Pop noise
>> during end of stream.
> 
> Wow, that hardware sounds *super* fragile.
> 
>> Moving the mute/unmute to trigger stop/start respectively seems to
>> help a lot with this Click/Pop issues reported on this Codec.
> 
>> +static int wsa883x_trigger(struct snd_pcm_substream *s, int cmd,
>> +			   struct snd_soc_dai *dai)
>> +{
>> +	switch (cmd) {
>> +	case SNDRV_PCM_TRIGGER_START:
>> +	case SNDRV_PCM_TRIGGER_RESUME:
>> +	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
>> +		wsa883x_digital_mute(dai, false, 0);
>> +		break;
> 
>>   static const struct snd_soc_dai_ops wsa883x_dai_ops = {
>> +	.startup = wsa883x_startup,
>>   	.hw_params = wsa883x_hw_params,
>>   	.hw_free = wsa883x_hw_free,
>> -	.mute_stream = wsa883x_digital_mute,
>> +	.trigger = wsa883x_trigger,
> 
> The trigger is run in atomic context, can you really write safely to a
> SoundWire device there?
> 
> This feels like we should be doing it at the framework level, either
> tightening up where the mute happens in general or having some option
> that devices can select if they really need it.
That makes more sense, I can give that a try.

--srini