ref-manual: document devicetree class variables

Document the newly added DT_FILES variable and closely related
DT_FILES_PATH. Also add DT_PADDING_SIZE to the glossary.

Signed-off-by: Petr Kubizňák <kubiznak@2n.com>
---
 documentation/ref-manual/classes.rst   |  9 +++++++--
 documentation/ref-manual/variables.rst | 22 ++++++++++++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

Hello Petr,

Many thanks for the patch!

On 09.05.23 at 16:03, Petr Kubizňák wrote:
> Document the newly added DT_FILES variable and closely related
> DT_FILES_PATH. Also add DT_PADDING_SIZE to the glossary.
>
> Signed-off-by: Petr Kubizňák <kubiznak@2n.com>
> ---
>   documentation/ref-manual/classes.rst   |  9 +++++++--
>   documentation/ref-manual/variables.rst | 22 ++++++++++++++++++++++
>   2 files changed, 29 insertions(+), 2 deletions(-)
>
> diff --git a/documentation/ref-manual/classes.rst b/documentation/ref-manual/classes.rst
> index ab1628401..94b6a3ebd 100644
> --- a/documentation/ref-manual/classes.rst
> +++ b/documentation/ref-manual/classes.rst
> @@ -607,10 +607,15 @@ subdirectory. This avoids clashes with the :ref:`ref-classes-kernel-devicetree`
>   output. Additionally, the device trees are populated into the sysroot for
>   access via the sysroot from within other recipes.
>   
> +By default, all device tree sources located in :term:`DT_FILES_PATH` directory
> +are compiled. To select only particular sources, set :term:`DT_FILES` to
> +a space-separated list of files (relative to :term:`DT_FILES_PATH`). For
> +convenience, both ``.dts`` and ``.dtb`` extensions can be used.
> +
>   An extra padding is appended to non-overlay device trees binaries. This
>   can typically be used as extra space for adding extra properties at boot time.
> -The padding size can be modified by setting ``DT_PADDING_SIZE`` to the desired
> -size, in bytes.
> +The padding size can be modified by setting :term:`DT_PADDING_SIZE`
> +to the desired size, in bytes.
>   
>   See :oe_git:`devicetree.bbclass sources
>   </openembedded-core/tree/meta/classes-recipe/devicetree.bbclass>`
> diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
> index 6ee65e178..4b69843d4 100644
> --- a/documentation/ref-manual/variables.rst
> +++ b/documentation/ref-manual/variables.rst
> @@ -2247,6 +2247,28 @@ system and gives an overview of their function and contents.
>         For information on policies and on how to use this variable, see the
>         comments in the ``meta/classes-recipe/compress_doc.bbclass`` file.
>   
> +   :term:`DT_FILES`
> +      Space-separated list of device tree source files to compile using
> +      a recipe that inherits the :ref:`ref-classes-devicetree` class. These
> +      are relative to the :term:`DT_FILES_PATH`.
> +
> +      For convenience, both ``.dts`` and ``.dtb`` extensions can be used.
> +
> +      Use an empty string (default) to build all device tree sources within
> +      the :term:`DT_FILES_PATH` directory.
> +
> +   :term:`DT_FILES_PATH`
> +      When compiling out-of-tree device tree sources using a recipe that
> +      inherits the :ref:`ref-classes-devicetree` class, this variable specifies
> +      the path to the directory containing dts files to build.
> +
> +      Defaults to the :term:`S` directory.
> +
> +   :term:`DT_PADDING_SIZE`
> +      When inheriting the :ref:`ref-classes-devicetree` class, this variable
> +      specifies the size of padding appended to the device tree blob, used as
> +      extra space typically for additional properties during boot.
> +
>      :term:`EFI_PROVIDER`
>         When building bootable images (i.e. where ``hddimg``, ``iso``, or
>         ``wic.vmdk`` is in :term:`IMAGE_FSTYPES`), the


Everything looks good, thanks again!
Reviewed-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
... and merged into "master-next" (not too late to take further comments 
into account, though).

Cheers
Michael.