linux-kernel - Re: [PATCH 1/2] dt-bindings: i2c: Add MediaTek i2c AC timing binding

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Message-ID: <1563368121.16970.7.camel@mhfsdcap03>
Date:   Wed, 17 Jul 2019 20:55:21 +0800
From:   Qii Wang <qii.wang@...iatek.com>
To:     Wolfram Sang <wsa@...-dreams.de>
CC:     <linux-i2c@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>,
        <srv_heupstream@...iatek.com>, <leilk.liu@...iatek.com>,
        <matthias.bgg@...il.com>, <robh+dt@...nel.org>
Subject: Re: [PATCH 1/2] dt-bindings: i2c: Add MediaTek i2c AC timing binding

On Wed, 2019-06-26 at 15:39 +0200, Wolfram Sang wrote:
> Hi,
> 
> On Tue, Jun 11, 2019 at 04:11:54PM +0800, Qii Wang wrote:
> > Add i2c AC timing binding to binding file. It can give the AC
> > timing parameters to meet I2C specification at different speed.
> > 
> > Signed-off-by: Qii Wang <qii.wang@...iatek.com>
> 
> I think this is a too specific 1:1 mapping of your register set into DT
> world. We already have these generic parameters:
> 
> - clock-frequency
>         frequency of bus clock in Hz.
> 
> - i2c-scl-falling-time-ns
>         Number of nanoseconds the SCL signal takes to fall; t(f) in the I2C
>         specification.
> 
> - i2c-scl-internal-delay-ns
>         Number of nanoseconds the IP core additionally needs to setup SCL.
> 
> - i2c-scl-rising-time-ns
>         Number of nanoseconds the SCL signal takes to rise; t(r) in the I2C
>         specification.
> 
> - i2c-sda-falling-time-ns
>         Number of nanoseconds the SDA signal takes to fall; t(f) in the I2C
>         specification.
> 
> (check Documentation/devicetree/bindings/i2c/i2c.txt)
> 
> Can't you use those to derive your values from that? Which ones are you missing
> if not?
> 
> Regards,
> 
>    Wolfram

I have take a little time to develop a new patch which based on your
suggestions, and it tested OK. Thanks for your suggestions, I will
update the patch after I test it fully.