linux-kernel - Re: [PATCH 2/4] dt-bindings: input: touchscreen: fsl,imx6ul-tsc: add fsl,glitch-threshold

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Message-ID: <CABGWkvpWPXz8bFPC3OgqY+C6cgu6hHGh6muCQkoCOEVK048fSA@mail.gmail.com>
Date: Wed, 23 Jul 2025 08:25:43 +0200
From: Dario Binacchi <dario.binacchi@...rulasolutions.com>
To: Rob Herring <robh@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-amarula@...rulasolutions.com, 
	Conor Dooley <conor+dt@...nel.org>, Dmitry Torokhov <dmitry.torokhov@...il.com>, 
	Fabio Estevam <festevam@...il.com>, Haibo Chen <haibo.chen@....com>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Pengutronix Kernel Team <kernel@...gutronix.de>, 
	Sascha Hauer <s.hauer@...gutronix.de>, Shawn Guo <shawnguo@...nel.org>, devicetree@...r.kernel.org, 
	imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
	linux-input@...r.kernel.org
Subject: Re: [PATCH 2/4] dt-bindings: input: touchscreen: fsl,imx6ul-tsc: add fsl,glitch-threshold

On Wed, Jul 23, 2025 at 7:03 AM Rob Herring <robh@...nel.org> wrote:
>
> On Tue, Jul 22, 2025 at 12:36:16PM +0200, Dario Binacchi wrote:
> > Add support for glitch threshold configuration. A detected signal is valid
> > only if it lasts longer than the set threshold; otherwise, it is regarded
> > as a glitch.
> >
> > Signed-off-by: Dario Binacchi <dario.binacchi@...rulasolutions.com>
> > ---
> >
> >  .../input/touchscreen/fsl,imx6ul-tsc.yaml      | 18 ++++++++++++++++++
> >  1 file changed, 18 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/input/touchscreen/fsl,imx6ul-tsc.yaml b/Documentation/devicetree/bindings/input/touchscreen/fsl,imx6ul-tsc.yaml
> > index 678756ad0f92..2fee2940213f 100644
> > --- a/Documentation/devicetree/bindings/input/touchscreen/fsl,imx6ul-tsc.yaml
> > +++ b/Documentation/devicetree/bindings/input/touchscreen/fsl,imx6ul-tsc.yaml
> > @@ -62,6 +62,23 @@ properties:
> >      description: Number of data samples which are averaged for each read.
> >      enum: [ 1, 4, 8, 16, 32 ]
> >
> > +  fsl,glitch-threshold:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    default: 0
> > +    enum: [ 0, 1, 2, 3 ]
> > +    description: |
> > +      Indicates the glitch threshold. The threshold is defined by number
> > +      of clock cycles. A detect signal is only valid if it is exist longer
> > +      than threshold; otherwise, it is regarded as a glitch.
> > +      0: Normal function: 8191 clock cycles
> > +         Low power mode: 9 clock cycles
> > +      1: Normal function: 4095 clock cycles
> > +         Low power mode: 7 clock cycles
> > +      2: Normal function: 2047 clock cycles
> > +         Low power mode: 5 clock cycles
> > +      3: Normal function: 1023 clock cycles
> > +         Low power mode: 3 clock cycles
>
> Don't we have common properties for this expressed in time? Debounce
> time IIRC.

I tried checking in
Documentation/devicetree/bindings/input/touchscreen/touchscreen.yaml,
but I didn't find anything about it.

It exists in some specific touchscreen bindings:
- azoteq,iqs7211.yaml
- brcm,iproc-touchscreen.txt
- fsl-mx25-tcq.txt,
- ti,ads7843.yaml.

Only fsl-mx25-tcq.txt expresses it in terms of time (ns).

Thanks and regards,
Dario

>
> > +
> >  required:
> >    - compatible
> >    - reg
> > @@ -94,4 +111,5 @@ examples:
> >          measure-delay-time = <0xfff>;
> >          pre-charge-time = <0xffff>;
> >          touchscreen-average-samples = <32>;
> > +        fsl,glitch-threshold = <2>;
> >      };
> > --
> > 2.43.0
> >



-- 

Dario Binacchi

Senior Embedded Linux Developer

dario.binacchi@...rulasolutions.com

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