RE: [EXT] Re: [PATCH 1/3] dt-bindings: i2c: add optional mul-value property to binding

[Chuanhua Han]

> -----Original Message-----
> From: Rob Herring <robh@xxxxxxxxxx>
> Sent: 2019年5月3日 4:59
> To: Chuanhua Han <chuanhua.han@xxxxxxx>
> Cc: mark.rutland@xxxxxxx; shawnguo@xxxxxxxxxx; s.hauer@xxxxxxxxxxxxxx;
> Leo Li <leoyang.li@xxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> linux-i2c@xxxxxxxxxxxxxxx; kernel@xxxxxxxxxxxxxx; dl-linux-imx
> <linux-imx@xxxxxxx>; festevam@xxxxxxxxx;
> wsa+renesas@xxxxxxxxxxxxxxxxxxxx; u.kleine-koenig@xxxxxxxxxxxxxx;
> eha@xxxxxxxx; linux@xxxxxxxxxxxxxxxx; Sumit Batra <sumit.batra@xxxxxxx>;
> l.stach@xxxxxxxxxxxxxx; peda@xxxxxxxxxx
> Subject: [EXT] Re: [PATCH 1/3] dt-bindings: i2c: add optional mul-value
> property to binding
> 
> Caution: EXT Email
> 
> On Tue, Apr 30, 2019 at 12:32:40PM +0800, Chuanhua Han wrote:
> > NXP Layerscape SoC have up to three MUL options available for all
> > divider values, we choice of MUL determines the internal monitor rate
> > of the I2C bus (SCL and SDA signals):
> > A lower MUL value results in a higher sampling rate of the I2C signals.
> > A higher MUL value results in a lower sampling rate of the I2C signals.
> >
> > So in Optional properties we added our custom mul-value property in
> > the binding to select which mul option for the device tree i2c
> > controller node.
> >
> > Signed-off-by: Chuanhua Han <chuanhua.han@xxxxxxx>
> > ---
> >  Documentation/devicetree/bindings/i2c/i2c-imx.txt | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-imx.txt
> > b/Documentation/devicetree/bindings/i2c/i2c-imx.txt
> > index b967544590e8..ba8e7b7b3fa8 100644
> > --- a/Documentation/devicetree/bindings/i2c/i2c-imx.txt
> > +++ b/Documentation/devicetree/bindings/i2c/i2c-imx.txt
> > @@ -18,6 +18,9 @@ Optional properties:
> >  - sda-gpios: specify the gpio related to SDA pin
> >  - pinctrl: add extra pinctrl to configure i2c pins to gpio function for i2c
> >    bus recovery, call it "gpio" state
> > +- mul-value: NXP Layerscape SoC have up to three MUL options
> > +available for all I2C divider values, it describes which MUL we
> > +choose to use for the driver, the values should be 1,2,4.
> 
> Needs a vendor prefix. I don't find 'value' to add anything nor do I understand
> what MUL is.
Yes,you are right!
> 
> If it is determined by SoC rather than board, then it should perhaps be implied
> by compatible.
This is determined by the SOC, but it has three options to choose from, 
so I think it's better to use the optional option instead of compatible

> 
> Rob