Re: [PATCH 0/2] Adds designware i2c module and adds it to virt arm

[Philippe Mathieu-Daudé]

+Enrico Weigelt

On 26/1/22 19:03, Peter Maydell wrote:
> On Wed, 26 Jan 2022 at 17:12, Chris Rauer <crauer@google.com> wrote:
> > > I need to see a pretty strong justification for why we should be
> > > adding new kinds of devices to the virt machine,
> >
> > The designware i2c controller is a very common controller on many
> >   ARM SoCs.  It has device tree bindings and ACPI bindings which
> > makes it ideal for this platform.
>
> No, I mean, why do we need an i2c controller on the virt
> board at all ?
>
> > > Forgot to mention, but my prefered approach for providing
> > > an i2c controller on the virt board would be to have a
> > > PCI i2c controller: that way users who do need it can plug it
> > > in with a -device command line option, and users who don't
> > > need it never have to worry about it.
>
> > > (We seem to have an ICH9-SMB PCI device already; I have no idea if it's 
> > > suitable.)
> > I didn't find that device suitable because it is part of the Intel
> > Southbridge, which may have some Intel platform quirks, and
> > we don't need all the things in that IO hub.
>
> That's a pity. Is there a different PCI I2C controller we could model ?

What about using virtio-gpio & bitbang I2C?

- virtio-gpio
https://lore.kernel.org/qemu-devel/20201127182917.2387-5-info@metux.net/

- bitbang I2C already in: hw/i2c/bitbang_i2c.c

Regards,

Phil.