linux-kernel - Re: [PATCH v4 2/9] dt-bindings: i2c: add bindings for i2c analog and digital filter

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Date:   Mon, 2 Sep 2019 10:49:08 +0000
From:   Peter Rosin <peda@...ntia.se>
To:     "Eugen.Hristev@...rochip.com" <Eugen.Hristev@...rochip.com>,
        "wsa@...-dreams.de" <wsa@...-dreams.de>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "Ludovic.Desroches@...rochip.com" <Ludovic.Desroches@...rochip.com>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "pierre-yves.mordret@...com" <pierre-yves.mordret@...com>,
        "alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>
CC:     "Nicolas.Ferre@...rochip.com" <Nicolas.Ferre@...rochip.com>
Subject: Re: [PATCH v4 2/9] dt-bindings: i2c: add bindings for i2c analog and
 digital filter

On 2019-09-02 12:12, Eugen.Hristev@...rochip.com wrote:
> From: Eugen Hristev <eugen.hristev@...rochip.com>
> 
> Some i2c controllers have a built-in digital or analog filter.
> This is specifically required depending on the hardware PCB/board.
> Some controllers also allow specifying the maximum width of the
> spikes that can be filtered. The width length can be specified in nanoseconds.
> 
> Signed-off-by: Eugen Hristev <eugen.hristev@...rochip.com>
> ---
>  Documentation/devicetree/bindings/i2c/i2c.txt | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/i2c/i2c.txt b/Documentation/devicetree/bindings/i2c/i2c.txt
> index 44efafd..8dbff67 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c.txt
> @@ -55,6 +55,17 @@ wants to support one of the below features, it should adapt the bindings below.
>  	Number of nanoseconds the SDA signal takes to fall; t(f) in the I2C
>  	specification.
>  
> +- i2c-analog-filter
> +	Enable analog filter for i2c lines.
> +
> +- i2c-digital-filter
> +	Enable digital filter for i2c lines.
> +
> +- i2c-filter-width-ns
> +	Width of spikes which can be filtered by either digital or analog
> +	filters (i2c-analog-filtr or i2c-digital-filtr). This width is specified

filtr -> filter (two instances)

What if you want/need to have different bandwidth for the digital and analog
filters? After all, this is a generic binding...

Cheers,
Peter

> +	in nanoseconds.
> +
>  - interrupts
>  	interrupts used by the device.
>  
>