[v3 2/2] doc: process.rst: Document device tree resync rules

[Quentin Schulz]

Hi Tom,

On 5/17/24 7:49 PM, Tom Rini wrote:
> Document the logic of when we do a full resync of the device trees used
> by OF_UPSTREAM as well as that cherry-picking is allowed as needed.
> 
> Signed-off-by: Tom Rini <trini at konsulko.com>
> ---
> Changes in v3:
> - Actually commit the changes I intended for v2
> 
> Changes in v2:
> - Address Quentin's feedback
> 
> Cc: Heinrich Schuchardt <xypron.glpk at gmx.de>
> Cc: Quentin Schulz <quentin.schulz at cherry.de>
> ---
>   doc/develop/devicetree/control.rst |  9 ++++++---
>   doc/develop/process.rst            | 13 +++++++++++++
>   2 files changed, 19 insertions(+), 3 deletions(-)
> 
> diff --git a/doc/develop/devicetree/control.rst b/doc/develop/devicetree/control.rst
> index 4cc1457d4ea8..ca4fb0b5b10f 100644
> --- a/doc/develop/devicetree/control.rst
> +++ b/doc/develop/devicetree/control.rst
> @@ -113,9 +113,12 @@ SoC being used via Kconfig and set `DEFAULT_DEVICE_TREE=<vendor>/<name>` when
>   prompted by Kconfig.
>   
>   However, if `dts/upstream/` hasn't yet received devicetree source file for your
> -newly added board support then you can add corresponding devicetree source file
> -as `arch/<arch>/dts/<name>.dts`. To select that add `# CONFIG_OF_UPSTREAM is not
> -set` and set `DEFAULT_DEVICE_TREE=<name>` when prompted by Kconfig.
> +newly added board support then one option is that you can add the corresponding
> +devicetree source file as `arch/<arch>/dts/<name>.dts`. To select that add `#
> +CONFIG_OF_UPSTREAM is not set` and set `DEFAULT_DEVICE_TREE=<name>` when

I don't like the wording here because it implies we should modify the 
defconfig by hand, which nobody should ever do.

I could suggest:
"""
To do that, unselect `OF_UPSTREAM` and set `DEFAULT_DEVICE_TREE=<name>` 
through a Kconfig tool (e.g. `menuconfig`).
"""

In any case, this is wording is not added in this patch, so I guess we 
could fix it in another patch as well, making this remark not a "blocker".

> +prompted by Kconfig. Another option is that you can use use the "pick" option of
> +`dts/update-dts-subtree.sh` mentioned above to bring in the commits that you
> +need.
>   
>   This should include your CPU or SoC's devicetree file. On top of that any U-Boot
>   specific tweaks (see: :ref:`dttweaks`) can be made for your board.
> diff --git a/doc/develop/process.rst b/doc/develop/process.rst
> index a66540a698c1..0542b3fc1245 100644
> --- a/doc/develop/process.rst
> +++ b/doc/develop/process.rst
> @@ -108,6 +108,19 @@ Differences to the Linux Development Process
>     In U-Boot, ``"-rc1"`` will only be released after all (or at least most of
>     the) patches that were submitted during the merge window have been applied.
>   
> +Resyncing of the device tree subtree
> +------------------------------------
> +
> +As explained in :doc:`devicetree/control` some platforms make use of device tree
> +files which come from a git subtree that mirrors the Linux Kernel sources
> +itself. For our purposes, we only track releases and not release candidates for
> +merging in our tree. These merges follow the normal merge window rules.
> +
> +In the case of specific changes, such as bug fixes or new platform support,
> +these can be "cherry-picked" and are subject to the normal merge rules. For
> +example, a bug fix can come in later in the window but a full re-sync only
> +happens within the merge window itself.
> +

Reviewed-by: Quentin Schulz <quentin.schulz at cherry.de>

Thanks,
Quentin