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

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@amarulasolutions.com>
---

 .../input/touchscreen/fsl,imx6ul-tsc.yaml      | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
  

> -----Original Message-----
> From: Dario Binacchi <dario.binacchi@amarulasolutions.com>
> Sent: 2025年7月22日 18:36
> To: linux-kernel@vger.kernel.org
> Cc: linux-amarula@amarulasolutions.com; Dario Binacchi
> <dario.binacchi@amarulasolutions.com>; Conor Dooley
> <conor+dt@kernel.org>; Dmitry Torokhov <dmitry.torokhov@gmail.com>;
> Fabio Estevam <festevam@gmail.com>; Bough Chen <haibo.chen@nxp.com>;
> Krzysztof Kozlowski <krzk+dt@kernel.org>; Pengutronix Kernel Team
> <kernel@pengutronix.de>; Rob Herring <robh@kernel.org>; Sascha Hauer
> <s.hauer@pengutronix.de>; Shawn Guo <shawnguo@kernel.org>;
> devicetree@vger.kernel.org; imx@lists.linux.dev;
> linux-arm-kernel@lists.infradead.org; linux-input@vger.kernel.org
> Subject: [PATCH 2/4] dt-bindings: input: touchscreen: fsl,imx6ul-tsc: add
> fsl,glitch-threshold
> 
> 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@amarulasolutions.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

Here the default should be 2 according to your third patch.

I'm okay for this patch set, let's waiting for comments about this yaml change.

By the way, any real case which need to use other glitch threshod?

Regards
Haibo Chen

> +    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
> +
>  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

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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@amarulasolutions.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.

> +
>  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
> 

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Hi Bough,

On Wed, Jul 23, 2025 at 4:45 AM Bough Chen <haibo.chen@nxp.com> wrote:
>
> > -----Original Message-----
> > From: Dario Binacchi <dario.binacchi@amarulasolutions.com>
> > Sent: 2025年7月22日 18:36
> > To: linux-kernel@vger.kernel.org
> > Cc: linux-amarula@amarulasolutions.com; Dario Binacchi
> > <dario.binacchi@amarulasolutions.com>; Conor Dooley
> > <conor+dt@kernel.org>; Dmitry Torokhov <dmitry.torokhov@gmail.com>;
> > Fabio Estevam <festevam@gmail.com>; Bough Chen <haibo.chen@nxp.com>;
> > Krzysztof Kozlowski <krzk+dt@kernel.org>; Pengutronix Kernel Team
> > <kernel@pengutronix.de>; Rob Herring <robh@kernel.org>; Sascha Hauer
> > <s.hauer@pengutronix.de>; Shawn Guo <shawnguo@kernel.org>;
> > devicetree@vger.kernel.org; imx@lists.linux.dev;
> > linux-arm-kernel@lists.infradead.org; linux-input@vger.kernel.org
> > Subject: [PATCH 2/4] dt-bindings: input: touchscreen: fsl,imx6ul-tsc: add
> > fsl,glitch-threshold
> >
> > 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@amarulasolutions.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
>
> Here the default should be 2 according to your third patch.

I considered the default value of the register, not the driver's.
If I'm not mistaken, the dt-bindings should be a description of the
hardware, not of the associated driver implementation.

>
> I'm okay for this patch set, let's waiting for comments about this yaml change.
>
> By the way, any real case which need to use other glitch threshod?

We recently submitted
https://lore.kernel.org/all/aGUDza5XRGDqfz5n@dragon/#t, and in this
initial contribution we removed all the custom parts that are not
supported upstream. This is
one such case. For our board, we need a de_glitch value of 1.

Thanks and regards,
Dario

>
> Regards
> Haibo Chen
>
> > +    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
> > +
> >  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
>
  

On Wed, Jul 23, 2025 at 7:03 AM Rob Herring <robh@kernel.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@amarulasolutions.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
> >
  

Hello Rob,

just a gentle ping — I’ve replied to your comments on this patch, but
I haven’t seen any further feedback.

Thanks and regards,
Dario

On Wed, Jul 23, 2025 at 8:25 AM Dario Binacchi
<dario.binacchi@amarulasolutions.com> wrote:
>
> On Wed, Jul 23, 2025 at 7:03 AM Rob Herring <robh@kernel.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@amarulasolutions.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@amarulasolutions.com
>
> __________________________________
>
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