On Mon, 2021-03-29 at 14:59 +0300, Andy Shevchenko wrote:

On Mon, Mar 29, 2021 at 2:43 PM Matti Vaittinen
[off-list ref] wrote:

quoted

The checkpacth instructs to switch from ENOSUPP to EOPNOTSUPP.

quoted

WARNING: ENOTSUPP is not a SUSV4 error code, prefer EOPNOTSUPP

Make the gpiolib allow drivers to return both so driver developers
can avoid one of the checkpatch complaints.

Internally we are fine to use the ENOTSUPP.
Checkpatch false positives there.

I agree. OTOH, the checkpatch check makes sense to user-visible stuff.
Yet, the checkpatch has hard time guessing what is user-visible - so it
probably is easiest to nag about all ENOTSUPP uses as it does now.

I doubt we need this change. Rather checkpatch should rephrase this
to
point out that this is only applicable to _user-visible_ error path.
Cc'ed Joe.

Yes, thanks for pulling Joe in.

Anyways, no matter what the warning says, all false positives are
annoying. I don't see why we should stay with ENOTSUPP in gpiolib?
(other than the burden of changing it).

But I have no strong opinion on this. All options I see have downsides.

Accepting both ENOTSUPP and EOPNOTSUPP is the easy way to avoid
allowing checkpatch warnings - but I admit it isn't stylish. 

Converting all ENOTSUPP cases inside gpiolib to EOPNOTSUPP is teodious
although end result might be nicer.

Leaving it as is gives annoying false-positives to driver developers.

My personal preference was this patch - others can have other view like
Andy does. I'll leave this to community/maintainers to evaluate :)

Best Regards
	Matti Vaittinen