linux-kernel - RE: Re: [PATCH 2/4] ASoC: dt-bindings: wlf,wm8524: Add a property to specify power up sequency time

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Date:   Mon, 27 Feb 2023 09:06:47 +0000
From:   Chancel Liu <chancel.liu@....com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        "lgirdwood@...il.com" <lgirdwood@...il.com>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "perex@...ex.cz" <perex@...ex.cz>,
        "tiwai@...e.com" <tiwai@...e.com>,
        "ckeepax@...nsource.cirrus.com" <ckeepax@...nsource.cirrus.com>,
        "patches@...nsource.cirrus.com" <patches@...nsource.cirrus.com>,
        "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: RE: Re: [PATCH 2/4] ASoC: dt-bindings: wlf,wm8524: Add a property to
 specify power up sequency time

> On 24/02/2023 11:54, Chancel Liu wrote:
> >> On 22/02/2023 12:39, Chancel Liu wrote:
> >>> This property specifies power up to audio out time. It's necessary
> >>> beacause this device has to wait some time before ready to output audio
> >>
> >> typo... run spellcheck, also on the subject
> >>
> >>> after MCLK, BCLK and MUTE=1 are enabled. For more details about the
> >>> timing constraints, please refer to WTN0302 on
> >>>
> >>>
> >>> Signed-off-by: Chancel Liu <chancel.liu@....com>
> >>> ---
> >>>  .../devicetree/bindings/sound/wlf,wm8524.yaml          | 10
> >> ++++++++++
> >>>  1 file changed, 10 insertions(+)
> >>>
> >>> diff --git a/Documentation/devicetree/bindings/sound/wlf,wm8524.yaml
> >> b/Documentation/devicetree/bindings/sound/wlf,wm8524.yaml
> >>> index 09c54cc7de95..54b4da5470e4 100644
> >>> --- a/Documentation/devicetree/bindings/sound/wlf,wm8524.yaml
> >>> +++ b/Documentation/devicetree/bindings/sound/wlf,wm8524.yaml
> >>> @@ -21,6 +21,15 @@ properties:
> >>>      description:
> >>>        a GPIO spec for the MUTE pin.
> >>>
> >>> +  wlf,power-up-delay-ms:
> >>> +    maximum: 1500
> >>
> >> maximum is 1003. Where do you see 1500?
> >>
> >> minimum: 82
> >>
> >
> > Yes, you are absolutely right. From the power up to audio out timing table in
> > WTN0302, the minimum number is 82 and the maximum is 1003.
> >
> > Consider the following possibilities:
> > 1. These timings may depend on the system design
> > 2. These timings may be simulated results
> > 3. These timings may be the minimum values
> >
> > I set a larger value trying to extend the time. The larger value of course
> > introduces unwanted time delay but it benefits on avoiding beginning audio
> > lost.
> >
> > I also did some tests on a board. If I want to work on 48KHZ sample rate and
> > 512FS, the recommended value is 143. But the test result showed 143ms is not
> > enough. I increased the value to 500ms and could hear the beginning sound.
> 
> Maybe you miss proper regulator ramp-up?
> 
> >
> > Maybe it's a better choice to let DT set the suitable value? Is there a similar
> > situation before?
> 
> That's not really good argument. DT should describe hardware and if this
> property does not match hardware, it means you mix this with something
> else. Something not for DT.
> 
> 
> Best regards,
> Krzysztof

OK. The patches for adding such property are not really good. I need to find a
better way to address the issue.

I think PATCH 1 and PATCH 3 can be kept. So I will modify them according
comments.

Thank you for your review. That benefits me a lot.

Regards, 
Chancel Liu