[PATCH] docs: dt: writing-schema: Document usage of CHECK_DTBS make flag

[Nícolas F. R. A. Prado]

On Thu, Nov 03, 2022 at 10:19:15AM +0100, AngeloGioacchino Del Regno wrote:
> Il 02/11/22 22:43, Nícolas F. R. A. Prado ha scritto:
> > It is possible to run checks on a Devicetree by passing the CHECK_DTBS
> > flag when building. This is a useful shortcut to the dtbs_check make
> > target since it avoids checking unrelated Devicetrees, which can take
> > some time and is unnecessary if no bindings were modified. Document it.
> > 
> > Signed-off-by: Nícolas F. R. A. Prado <nfraprado at collabora.com>
> >  > ---
> > 
> >   Documentation/devicetree/bindings/writing-schema.rst | 7 +++++++
> >   1 file changed, 7 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/writing-schema.rst b/Documentation/devicetree/bindings/writing-schema.rst
> > index 4a381d20f2b4..55ad556472b4 100644
> > --- a/Documentation/devicetree/bindings/writing-schema.rst
> > +++ b/Documentation/devicetree/bindings/writing-schema.rst
> > @@ -167,6 +167,13 @@ setting the ``DT_SCHEMA_FILES`` variable to a specific schema file or pattern.
> >       make dt_binding_check DT_SCHEMA_FILES=/gpio/
> >       make dtbs_check DT_SCHEMA_FILES=trivial-devices.yaml
> > +Note that ``make dtbs_check`` will validate every DT source file that is
> 
> "Note that xxxx" looks a bit repeated... read:
> 
> Note that ``dtbs_check`` will skip any binding schema files with errors.
> (etc etc)
> 
> Note that ``make dtbs_check`` will validate every DT source file ...
> (etc etc)
> 
> Perhaps we can change the first paragraph saying
> "In order to perform validation of DT source files, use..."
> to something like:
> 
> In order to perform validation of all DT source files, use the ``dtbs_check``
> target, or set the ``CHECK_DTBS`` variable to ``y`` when building specific DTs::
> 
> ::
> 
>     make dtbs_check
>     make CHECK_DTBS=y mediatek/mt8192-evb.dtb
> 
> Any opinion?

Something to keep in mind is that the purpose of this section is to describe how
to validate binding changes (both on the binding itself and in the DTs that use
them). For this, people really should be using dtbs_check since otherwise a new
warning might be missed. Using CHECK_DTBS is more suitable for a different use
case, which is to validate some dtbs without having changed the bindings, which
is why I added it at the end of the section more as a side note. For this
reason I think it's better to keep them separate.

About repeating the "Note that", that could just be changed for "It's worth
noting that" or something similar.

Thanks,
Nícolas