checkpatch is broken.
Heh, I'm not objecting it :)
OTOH, it's also true that ENOTSUPP is no good error code if returned to user-space. Unfortunately many codes (including what I wrote) use this code mistakenly, and they can't be changed any longer...
It's also used internally in various places without being returned to userspace, that's what's going on here - the regmap core has some specific checks for -ENOTSUPP.
Sure, for such an internal usage any code can be used. The question is a case like this -- where the return code might be carried to outside. Though, looking through the grep output, all callers simply return -EINVAL for any errors, so it doesn't matter much for now.
I assumed this change to -EOPNOTSUPP reflected a consensus in kernel-land, it's obviously not the case. This patch was supposed to be a trivial clean-up...
So to be clear, what is the direction for existing code a) keep -ENOTSUPP as is? b) move to -EOPNOTSUPP?
And what is the preference for new code?