Re: DT case sensitivity

[Rob Herring <robh@kernel.org>]

On Thu, Aug 23, 2018 at 4:02 AM Grant Likely <grant.likely@arm.com> wrote:
>
> On 23/08/2018 02:29, Benjamin Herrenschmidt wrote:
> > On Wed, 2018-08-22 at 20:26 -0500, Rob Herring wrote:
> >> On Wed, Aug 22, 2018 at 8:14 PM Benjamin Herrenschmidt
> >> <benh@kernel.crashing.org> wrote:
> >>>
> >>> On Wed, 2018-08-22 at 19:47 -0500, Rob Herring wrote:
> >>>> The default DT string handling in the kernel is node names and
> >>>> compatibles are case insensitive and property names are case sensitive
> >>>> (Sparc is the the only variation and is opposite). It seems only PPC
> >>>> (and perhaps only Power Macs?) needs to support case insensitive
> >>>> comparisons. It was probably a mistake to follow PPC for new arches
> >>>> and we should have made everything case sensitive from the start. So I
> >>>> have a few questions for the DT historians. :)
> >>>
> >>> Open Firmware itself is insensitive.
> >>
> >> Doesn't it depend on the implementation? Otherwise, how is Sparc different?
> >
> > Not sure ... Forth itself is insensitive for words but maybe not for
> > string comparisons.
>
> What problem are you trying to solve?

I'm looking at removing device_node.name and using full_name instead
(which now is only the local node name plus unit-address). This means
replacing of_node_cmp() (and still some strcmp) calls in a lot of
places. I need to use either strncmp or strncasecmp instead.

> I would think making everything
> case insensitive would be the direction to go if you do anything. Least
> possibility of breaking existing platforms in that scenario.

Really? Even if all the "new" arches are effectively case sensitive?
Anything using dtc and libfdt are (and json-schema certainly will be).
But I frequently say the kernel's job is not DT validation, so you
pass crap in, you get undefined results.

Rob