Ok, I see what you mean. I had a look at the place in question and
wonder what to return from i2c_add_mux_adapter() in the disabled
case so that i2c-mux-pinctrl is still happy with the returned value.

Ouch, you are right. The crux of interfaces returning NULL instead of an
ERR_PTR :( I'll have a look, I maybe started to fix this somewhen.

I guess what you want to have is that i2c_add_adapter() is not called
for the disabled case, right?

I think that makes sense.

Is the i2c_adapter struct prepared in i2c_mux_add_adapter() still valid
if i2c_add_adapter() is not called?

I will have a closer look to the issue this weekend.

Sorry, I am not too deep into i2c subsystem, I just reworked i2c-mux-
pinctrl to make it work on Dove. If you are fine with giving me some
guidance how you prefer to have it done, I can try to free some spare
time.

Cool, thanks. Learning by doing is a good way to get such knowledge :)

Unfortunately there is already little of it, so please don't
expect a quick tested patch.

I understand.

Thanks,

   Wolfram

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