Re: [PATCH 2/9] dt-bindings: i2c: qcom-cci: add description of a vbus-supply property

[Bjorn Andersson <bjorn.andersson@linaro.org>]

On Thu 03 Feb 08:46 PST 2022, Vladimir Zapolskiy wrote:

> Quite regularly I2C bus lines on QCOM CCI controller require an external
> pull-up to a regulator powered line, to be able to define all such
> cases an additional vbus-supply property of a bus subnode is wanted.
> 
> Signed-off-by: Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>
> ---
>  Documentation/devicetree/bindings/i2c/i2c-qcom-cci.txt | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-qcom-cci.txt b/Documentation/devicetree/bindings/i2c/i2c-qcom-cci.txt
> index 924ad8c03464..9f5b321748f1 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c-qcom-cci.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c-qcom-cci.txt
> @@ -60,6 +60,11 @@ PROPERTIES:
>  	Definition: Desired I2C bus clock frequency in Hz, defaults to 100
>  		    kHz if omitted.
>  
> +- vbus-supply:

I don't think "vbus" is an appropriate name for his. Perhaps "vddio" or
something like that would be better.

But there's a bigger question here, this is not a supply for the
i2c master, it's simply a supply for pulling up the bus. So it's not
entirely correct to specify it as a supply for the CCI node (which is
also the reason why the name isn't obvious).

Typically we don't don't mention the bus-supply because it happens to be
pulled up either by io-supply for the block, or by some always-on
regulator in the system.

Looping in Linus and Mark in hope they have seen this need elsewhere.

Regards,
Bjorn

> +	Usage: optional
> +	Value type: phandle
> +	Definition: Regulator that provides power to SCL/SDA lines
> +
>  Example:
>  
>  	cci@a0c000 {
> -- 
> 2.33.0
>