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

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On Tue, 8 Feb 2022 at 16:16, Mark Brown <broonie@kernel.org> wrote:
>
> On Mon, Feb 07, 2022 at 08:31:30PM +0200, Vladimir Zapolskiy wrote:
> > On 2/7/22 4:39 PM, Mark Brown wrote:
>
> > > The bindings are ABI, it doesn't seem like a good idea to add new ABI as
> > > a temporary bodge.

It's not a temporary bodge. The i2c-core piece was reverted, but not
the mediatek driver code/bindings.
Vladimir has provided a replacement for the i2c-core code handling the
vbus-regulator. When thee code will be back, the code from i2c-cci can
be removed. The bindings will be the same.

>
> > The bindings are supposed to describe hardware, thus it's natural to extend
> > them, I believe there is a trilemma in this particular case:
> > 1) add optional vbus-supply property to all I2C master controllers or I2C
> >    busses in case of multiple I2C busses managed by a single controller,
> > 2) add optional vbus-supply property to all I2C slave devices,
>
> If you add a named supply to all I2C controllers or devices then if any
> of them have an actual vbus supply there will be a namespace collision.
>
> > 3) ignore peculiarities of particular (multiple in fact) PCB designs and
> >    a necessity of adding a regulator finely described as a pull-up for I2C
> >    bus lines.
>
> There's also the option of representing this as a separate thing on or
> part of the bus.

4) (which you have implemented in your patch). Add support for  the
vbus-supplies property for the I2C CCI controllers.

This is the option I'd vote for.

-- 
With best wishes
Dmitry