Re: [PATCH v2 0/2] i2c: Add i2c-shared-gpio driver

[Rob Herring <robh@kernel.org>]

On Tue, May 12, 2026 at 01:00:08PM +0200, Bartosz Golaszewski wrote:
> On Mon, May 11, 2026 at 6:25 PM Markus Stockhausen
> <markus.stockhausen@gmx.de> wrote:
> >
> > This series adds support for hardware designs where multiple I2C
> > gpio based busses are realized with dedicated SDA lines and a
> > shared SCL line. This way N busses can be realized with N+1 gpios.
> >
> > Currently there are several Realtek switches that make use of
> > this design. Samples are:
> >
> > HPE 1920-48G
> > Linksys LGS310C
> > Zyxel GS1920-24
> > Engenius EWS2910
> > D-Link DGS-1250
> >
> > While at first glance this might be a usecase for the new shared
> > gpio architecture, discussion and testing shows that this is not
> > trivial at all. A shared gpio is handled by a voting system. If
> > there at least one user that votes for the GPIO to be "high",
> > it stays high.
> >
> > So the implementation manages several classic bitbang buses with
> > locking/unlocking in the pre_xfer/post_xfer handlers.
> >
> > Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
> >
> 
> Hi!
> 
> A couple high-level issues. You'll soon hear from the DT maintainers
> and they'll ask if the i2c-shared-gpio compatible corresponds with an
> actual piece of hardware on the board. It does not, so the bindings
> will be rejected.

Perhaps you missed I've already commented on this. I'm actually fine 
with the binding at a high level.

But if we want to model it as N i2c-gpio nodes I'm fine with that as 
well.

Rob