Re: [PATCH 2/2] gpiolib: Allow drivers to return EOPNOTSUPP from config

[Matti Vaittinen <matti.vaittinen@xxxxxxxxxxxxxxxxx>]

On Mon, 2021-03-29 at 14:59 +0300, Andy Shevchenko wrote:
> On Mon, Mar 29, 2021 at 2:43 PM Matti Vaittinen
> <matti.vaittinen@xxxxxxxxxxxxxxxxx> wrote:
> > The checkpacth instructs to switch from ENOSUPP to EOPNOTSUPP.
> > > 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