From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Eugen.Hristev@microchip.com
Cc: peda@axentia.se, wsa@the-dreams.de, mark.rutland@arm.com,
Ludovic.Desroches@microchip.com, linux-i2c@vger.kernel.org,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, pierre-yves.mordret@st.com,
robh+dt@kernel.org
Subject: Re: [PATCH v4 2/9] dt-bindings: i2c: add bindings for i2c analog and digital filter
Date: Mon, 2 Sep 2019 16:22:51 +0200 [thread overview]
Message-ID: <20190902142251.GC21922@piout.net> (raw)
In-Reply-To: <b6528812-65d3-6561-38e7-c0545af900d8@microchip.com>
Eugen,
On 02/09/2019 14:15:14+0000, Eugen.Hristev@microchip.com wrote:
> On 02.09.2019 13:49, Peter Rosin wrote:
>
> > On 2019-09-02 12:12, Eugen.Hristev@microchip.com wrote:
> >> From: Eugen Hristev <eugen.hristev@microchip.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@microchip.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...
>
> For our needs, this is enough: the purpose of the filters is to avoid
> noise on the lines, the noise is as big as it is for the digital and for
> the analog filters, since we use an absolute measurement for them. So I
> do not know how useful it would be to make a difference.
>
You are adding generic properties so they have to be generic and not
tied to your particular use case.
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
next prev parent reply other threads:[~2019-09-02 14:22 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-02 10:11 [PATCH v4 0/9] i2c: add support for filters Eugen.Hristev
2019-09-02 10:11 ` [PATCH v4 1/9] dt-bindings: i2c: at91: add new compatible Eugen.Hristev
2019-09-02 10:44 ` Peter Rosin
2019-09-02 14:12 ` Eugen.Hristev
2019-09-02 10:12 ` [PATCH v4 2/9] dt-bindings: i2c: add bindings for i2c analog and digital filter Eugen.Hristev
2019-09-02 10:49 ` Peter Rosin
2019-09-02 14:15 ` Eugen.Hristev
2019-09-02 14:22 ` Alexandre Belloni [this message]
2019-09-02 14:40 ` Peter Rosin
2019-09-02 15:47 ` Wolfram Sang
2019-09-02 10:12 ` [PATCH v4 3/9] i2c: add support for filter-width-ns optional property Eugen.Hristev
2019-09-02 10:12 ` [PATCH v4 4/9] i2c: at91: add new platform support for sam9x60 Eugen.Hristev
2019-09-02 10:12 ` [PATCH v4 5/9] i2c: at91: add support for digital filtering Eugen.Hristev
2019-09-02 10:12 ` [PATCH v4 6/9] i2c: at91: add support for advanced " Eugen.Hristev
2019-09-02 10:12 ` [PATCH v4 7/9] i2c: at91: add support for analog filtering Eugen.Hristev
2019-09-02 10:12 ` [PATCH v4 8/9] ARM: dts: at91: sama5d2_xplained: add analog and digital filter for i2c Eugen.Hristev
2019-09-02 10:12 ` [PATCH v4 9/9] ARM: dts: at91: sama5d4_xplained: add " Eugen.Hristev
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