Re: [PATCH v2 4/5] iio: magnetometer: ak8975: Drop deprecated enums from OF table

[Jonathan Cameron <jic23@kernel.org>]

On Fri, 6 Oct 2023 09:58:34 -0500
Rob Herring <robh@kernel.org> wrote:

> On Mon, Aug 28, 2023 at 9:22 AM Jonathan Cameron <jic23@kernel.org> wrote:
> >
> > On Fri, 18 Aug 2023 17:17:44 +0200
> > Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> >  
> > > Hi Andy,
> > >
> > > CC devicetree
> > >
> > > On Fri, Aug 18, 2023 at 5:03 PM Andy Shevchenko
> > > <andriy.shevchenko@linux.intel.com> wrote:  
> > > > On Fri, Aug 18, 2023 at 11:40:37AM +0000, Biju Das wrote:  
> > > > > > Subject: Re: [PATCH v2 4/5] iio: magnetometer: ak8975: Drop deprecated
> > > > > > enums from OF table
> > > > > >
> > > > > > On Fri, Aug 18, 2023 at 08:55:59AM +0100, Biju Das wrote:  
> > > > > > > Drop deprecated enums from OF table as corresponding entries are
> > > > > > > removed from bindings and it also saves memory.  
> > > > > >
> > > > > > You can't do this.
> > > > > >
> > > > > > Only sorting by "prefixed first" criteria is possible.  
> > > > >
> > > > > The rule applies only for fallback compatible. I checked bindings and I don't
> > > > > find any fallback compatibles. All compatibles are just enums. Am I missing
> > > > > anything here??  
> > > >
> > > > Yes. As per above patch. The _whole_ world is not under your / our control.
> > > > NAK to this change, sorry.  
> > >
> > > The single user ever in the upstream kernel was fixed in commit
> > > 9846210b1ec9bbaa ("ARM: tegra: seaboard: add missing DT vendor
> > > prefixes") in v3.8 back in 2012.
> > > And it had to be fixed again 9 years later in commit fa0fdb78cb5d4cde
> > > ("ARM: dts: am335x: Use correct vendor prefix for Asahi Kasei Corp.").
> > >
> > > There may be other out-of-tree users, which would be broken by this
> > > change.  Typically we wait a few years between deprecating a compatible
> > > value and removing support from the driver.
> > >
> > > As Biju is only deprecating these compatible values in PATCH 3/5 of
> > > his series, this may be a bit premature.  
> > Absolutely.  I'd go a bit further.
> > Unless there is a maintenance reason to remove these (after a few years from
> > removal in the binding doc) then we never remove them as it can only hurt users.  
> 
> I'm tracking undocumented compatibles (with 'make
> dt_compatible_check') in the kernel tree. Dropping the binding makes
> these undocumented (and now showing up in my diff between Linus and
> next). So please apply both or none.
> 
> Rob

Given I have some merges in the togreg tree and it's at least in theory
non rebasing, I'll revert patch 3 from this series rather than dropping it.

Thanks for letting me know.

Jonathan