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

[Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>]

Hi Bjorn, Mark,

On 2/4/22 9:32 PM, Mark Brown wrote:
> On Fri, Feb 04, 2022 at 11:02:04AM -0800, Bjorn Andersson wrote:
>> On Fri 04 Feb 10:42 PST 2022, Mark Brown wrote:
>>> On Fri, Feb 04, 2022 at 10:05:47AM -0800, Bjorn Andersson wrote:
> 
>>>> 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.
> 
>>> If the bus is being pulled up to some supply other than the supply that
>>> the bus is referenced to that doesn't sound like the greatest electrical
>>> engineering ever...  without any context it's hard to comment about this
>>> particular system.
> 
>> That's what the schematics says...
> 
> Oh, good.  I forsee no problems here.  Probably this is something that
> should be in the I2C core if it's going to be dynamically managed,
> though just setting the supply as always on is probably more expedient.
> 

vbus-supply property has been added recently to another I2C master controller,
see commit c021087c43c8 ("dt-binding: i2c: mt65xx: add vbus-supply property").
It serves right the same purpose, and its handling is going to be done in i2c
core, however since the latter is not yet completed, I would propose to add
the property to i2c-bus subnodes of QCOM CCI and its support in the driver,
later on both the property and its generic support would be better to see in
i2c core.

--
Best wishes,
Vladimir