Configuring device with I2C mux

[Alex Qiu]

Hi James,

I'll take a look at them. Thanks for pointing the related code out!

- Alex Qiu


On Wed, Jan 8, 2020 at 10:02 AM James Feist <james.feist at linux.intel.com>
wrote:

> On 1/8/20 9:54 AM, Alex Qiu wrote:
> > Hi James,
> >
> > Yes, we have multiple devices sitting behind the mux, and they're
> > onboard devices instead of standalone FRUs. The parent bus is described
> > as the FRU for each PCIe card.
> >
> > After naming the mux channels, can these names be used somehow to config
> > I2C devices? For example, {"Bus": "$bus", "ChannelNames":
> > ["C0", "C1", "C2", "C3"]} for the mux, and {"Bus": "$bus.C1"} for
> > devices behind the mux on channel 1.
>
> This syntax doesn't exist today.. On all our systems things behind the
> mux are again detectable, so we haven't hit this problem. Right now the
> template replacement is purely based on the found device on d-bus. So
> $bus is the bus property from the xyz.openbmc_project.FruDevice
> interface, there's no way to trace that to a mux channel, as it's just a
> d-bus property.
>
> The code you're looking for is here:
>
> https://github.com/openbmc/entity-manager/blob/01542d2af1b1f45335cc8813fffcd3ed07f22989/src/Utils.cpp#L144
>
>
> Along with the channel identification logic here:
>
> https://github.com/openbmc/entity-manager/blob/01542d2af1b1f45335cc8813fffcd3ed07f22989/src/Overlay.cpp#L112
>
> You could probably add some special syntax to make this work. Luckily
> this is the one part of entity-manager that is unit-tested, so that
> should help you
>
> https://github.com/openbmc/entity-manager/blob/master/test/test_entity-manager.cpp
>
>
> -James
>
>
>
>
>
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