Re: [PATCH v2 0/4] gpio: fix an incorrect lockdep warning

[Bartosz Golaszewski]

2016-09-18 10:52 GMT+02:00 Peter Rosin <peda@xxxxxxxxxx>:
> On 2016-09-16 19:58, Wolfram Sang wrote:
>>
>> Same here. And if it prevents us from false positive lockdep reports, I
>> am all for fixing it.
>
> Except it doesn't, when I think some more about it...
>
> If you have two gpio-expanders on the same depth but on different i2c
> branches you still end up with a splat if one is used to control a mux
> to reach the other.
>
> The only way to solve it for good, that I see, is to have every instance
> of the gpio-expander mutex in its own class. That might lead to many
> lockdep classes but then again, how many gpio expanders could there be
> in a system? A dozen or two seems extreme, so maybe that is the correct
> approach anyway?

Wouldn't it be enough to have a separate class for every base (as in:
not having any parent adapters) i2c adapter?

Best regards,
Bartosz Golaszewski