linux-kernel - Re: [PATCH] ASoC: rk3399_gru_sound: fix recording pop at first attempt

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Date:   Thu, 22 Sep 2016 21:50:42 +0800
From:   Xing Zheng <zhengxing@...k-chips.com>
To:     Mark Rutland <mark.rutland@....com>
Cc:     linux-rockchip@...ts.infradead.org, woojoo.lee@...sung.com,
        dianders@...omium.org, heiko@...ech.de, smbarber@...gle.com,
        hychao@...gle.com, cychiang@...gle.com,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ASoC: rk3399_gru_sound: fix recording pop at first
 attempt

Hi Mark,

On 2016年09月19日 22:44, Mark Rutland wrote:
> On Mon, Sep 19, 2016 at 10:29:39PM +0800, Xing Zheng wrote:
>> From: Wonjoon Lee <woojoo.lee@...sung.com>
>>
>> Pop happens when mclk applied but dmic's own boot-time
>> Specify dmic delay times in dt to make sure
>> clocks are ready earlier than dmic working
>>
>> Signed-off-by: Wonjoon Lee <woojoo.lee@...sung.com>
>> Signed-off-by: Xing Zheng <zhengxing@...k-chips.com>
>> ---
>>
>>   .../bindings/sound/rockchip,rk3399-gru-sound.txt   |    6 ++++++
>>   sound/soc/rockchip/rk3399_gru_sound.c              |   14 ++++++++++++++
>>   2 files changed, 20 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/sound/rockchip,rk3399-gru-sound.txt b/Documentation/devicetree/bindings/sound/rockchip,rk3399-gru-sound.txt
>> index f19b6c8..b7dd3ab 100644
>> --- a/Documentation/devicetree/bindings/sound/rockchip,rk3399-gru-sound.txt
>> +++ b/Documentation/devicetree/bindings/sound/rockchip,rk3399-gru-sound.txt
>> @@ -6,6 +6,12 @@ Required properties:
>>     connected to the codecs
>>   - rockchip,codec: The phandle of the MAX98357A/RT5514/DA7219 codecs
>>   
>> +Optional properties:
>> +- dmic-delay : specify delay time for DMIC ready.
>> +  If this option is specified, which means it's required dmic need
>> +  delay for DMIC to ready so that rt5514 can avoid recording before
>> +  DMIC send valid data
> What units is this in? Per the code it looks like ms, so if we follow
> Documentation/devicetree/bindings/property-units.txt, thous should be
> named something like dmic-enable-delay-ms.
OK, the "dmic-wakeup-delay-ms" have been done.
> That said, do we even need a property for this? Does this vary much in
> practice?
>
> If it does, can we not derive this delay from other information (e.g.
> the rates of input clocks and so on)? What exactly determines the
> necessary delay?
Yeah, the DMIC spec indicates wake-up time as 15ms max, so we need to 
start recording 15ms after MCLK after testing.

@Woojoo, please correct me if I was wrong.

Thanks.
>
> Thanks,
> Mark.
>
>>   
>>   sound {
>> diff --git a/sound/soc/rockchip/rk3399_gru_sound.c b/sound/soc/rockchip/rk3399_gru_sound.c
>> index 164b6da..6ab838b 100644
>> --- a/sound/soc/rockchip/rk3399_gru_sound.c
>> +++ b/sound/soc/rockchip/rk3399_gru_sound.c
>> @@ -37,6 +37,8 @@
>>   
>>   #define SOUND_FS	256
>>   
>> +unsigned int rt5514_dmic_delay;
>> +
>>   static struct snd_soc_jack rockchip_sound_jack;
>>   
>>   static const struct snd_soc_dapm_widget rockchip_dapm_widgets[] = {
>> @@ -122,6 +124,9 @@ static int rockchip_sound_rt5514_hw_params(struct snd_pcm_substream *substream,
>>   		return ret;
>>   	}
>>   
>> +	/* Wait for DMIC stable */
>> +	msleep(rt5514_dmic_delay);
>> +
>>   	return 0;
>>   }
>>   
>> @@ -334,6 +339,15 @@ static int rockchip_sound_probe(struct platform_device *pdev)
>>   		return -ENODEV;
>>   	}
>>   
>> +	/* Set DMIC delay */
>> +	ret = device_property_read_u32(&pdev->dev, "dmic-delay",
>> +					&rt5514_dmic_delay);
>> +	if (ret) {
>> +		rt5514_dmic_delay = 0;
>> +		dev_dbg(&pdev->dev,
>> +			"no optional property 'dmic-delay' found, default: no delay\n");
>> +	}
>> +
>>   	rockchip_dailinks[DAILINK_RT5514_DSP].cpu_name = kstrdup_const(dev_name(dev), GFP_KERNEL);
>>   	rockchip_dailinks[DAILINK_RT5514_DSP].cpu_dai_name = kstrdup_const(dev_name(dev), GFP_KERNEL);
>>   	rockchip_dailinks[DAILINK_RT5514_DSP].platform_name = kstrdup_const(dev_name(dev), GFP_KERNEL);
>> -- 
>> 1.7.9.5
>>
>>
>
>

-- 
- Xing Zheng