AW: AW: [PATCH 1/2] dt-bindings: i2c: Add i2c-shared-gpio

[<markus.stockhausen@gmx.de>]

> Von: Rob Herring <robh@kernel.org> 
> Gesendet: Mittwoch, 13. Mai 2026 18:21
> An: Wolfram Sang <wsa+renesas@sang-engineering.com>
> Betreff: Re: AW: [PATCH 1/2] dt-bindings: i2c: Add i2c-shared-gpio
> > ...
> > I am not sure i2c-mux is the right approach here. Because every SDA is 
> > already wired, there is no need to select/deselect something. It is 
> > only that SCL is shared, right?
>
> There's no physical select, but it's still only 1 active at any time just like a mux.

While working around this challenge my POV is as follows:

- See each SDA/SCL combination as an always hardwired bus 
- There is no muxing of the bus as a whole.
- It is only a question at what time access is allowed
- Why not expose each bus as simple as possible?

Coming back to my offer about the new I2C bus that only 
switches from compatible "i2c-gpio" to "i2c-gpio-shared". 
This should be achievable in the driver as follows:

- add each SDA to the individual bus
- build up a shared SCL list for all buses
- link each bus to the required SCL

That will need no shared gpio features. Managing the list 
should add ~100 lines and the rest of the driver can be 
reused/adapted.

Ideas, hints, objections?

Markus