Hi Michal,
On Wed, 20 Dec 2023 at 16:14, Michal Simek michal.simek@amd.com wrote:
Hi Sumit,
On 12/14/23 14:50, Sumit Garg wrote:
Prerquisite
This patch series requires devicetree-rebasing git repo to be added as a subtree to the main U-boot repo via:
$ git subtree add --prefix devicetree-rebasing \ git://git.kernel.org/pub/scm/linux/kernel/git/devicetree/devicetree-rebasing.git \ v6.6-dts --squash
Background
This effort started while I was reviewing patch series corresponding to Qcom platforms [1] which was about to import modified devicetree source files from Linux kernel. I suppose keeping devicetree files sync with Linux kernel without any DT bindings schema validation has been a pain for U-boot SoC/platform maintainers. There has been past discussions about a single DT repo but that hasn't come up and Linux kernel remained the place where DT source files as well as bindings are placed and maintained.
However, Linux kernel DT maintainers proposed [2] for U-boot to rather use devicetree-rebasing repo [3] which is a forked copy from Linux kernel for DT source files as well as bindings. It is tagged at every Linux kernel major release or intermideate release candidates. So here I have tried to reuse that to bring DT bingings compliance as well as a standard way to maintain a regular sync of DT source files with Linux kernel.
In order to maintain devicetree files sync, U-boot will maintains a Git subtree for devicetee-rebasing repo as `devicetee-rebasing/` sub-directory. It will be regularly updated with every new kernel major release via subtree pull as follows::
$ git subtree pull --prefix devicetree-rebasing \ git://git.kernel.org/pub/scm/linux/kernel/git/devicetree/devicetree-rebasing.git \ <release-tag> --squash
The RFC/prototype for this series has been discussed with Linux DT maintainers as well as U-boot maintainers here [4]. Now we would like to reach out to wider U-boot community to seek feedback.
[1] https://lore.kernel.org/all/CAFA6WYMLUD9cnkr=R0Uur+1UeTMkKjM2zDdMJtXb3nmrLk+... [2] https://lore.kernel.org/all/CAL_JsqKEjv2tSGmT+0ZiO7_qbBfhTycbGnhJhYpKDFzfO9j... [3] https://git.kernel.org/pub/scm/linux/kernel/git/devicetree/devicetree-rebasi... [4] https://github.com/u-boot/u-boot/pull/451
Changes
Traditionally, U-boot placed copies of devicetree source files from Linux kernel into `arch/<arch>/dts/<name>.dts`, which can be selected via:
CONFIG_DEFAULT_DEVICE_TREE "<name>"
SoC/board maintainers are encouraged to migrate to using mirrored copies from `devicetree-rebasing/` into `dts/arch/<arch>/<vendor>` via:
CONFIG_OF_UPSTREAM=y CONFIG_DEFAULT_DEVICE_TREE "<vendor>/<name>"
An example have been shown for Amlogic meson-gxbb SoC and corresponding derived boards via patch #7 and #8.
Devicetree bindings schema checks
With devicetee-rebasing Git subtree, the devicetree bindings are also regularly synced with Linux kernel as `devicetree-rebasing/Bindings/` sub-directory. This allows U-boot to run devicetree bindings schema checks which will bring compliance to U-boot core/drivers regarding usage of devicetree.
Dependencies
The DT schema project must be installed in order to validate the DT schema binding documents and validate DTS files using the DT schema. The DT schema project can be installed with pip:
$ pip3 install dtschema
Note that 'dtschema' installation requires 'swig' and Python development files installed first. On Debian/Ubuntu systems:
$ apt install swig python3-dev
Several executables (dt-doc-validate, dt-mk-schema, dt-validate) will be installed. Ensure they are in your PATH (~/.local/bin by default).
Recommended is also to install yamllint (used by dtschema when present).
Running checks
In order to perform validation of DTB files, use the ``dtbs_check`` target:
$ make dtbs_check
It is also possible to run checks with a subset of matching schema files by setting the ``DT_SCHEMA_FILES`` variable to 1 or more specific schema files or patterns (partial match of a fixed string). Each file or pattern should be separated by ':'.
$ make dtbs_check DT_SCHEMA_FILES=trivial-devices.yaml:rtc.yaml $ make dtbs_check DT_SCHEMA_FILES=/gpio/ $ make dtbs_check DT_SCHEMA_FILES=trivial-devices.yaml
Do you also plan to extend this to cover dt overlay + dt base generation and check it against DT schema.
I suppose here you are referring to DT schema checks for *.dtso -> *.dtbo generation. I don't see corresponding checks enabled in Linux kernel [1]. Probably Rob can share plans over there.
U-Boot tries to follow Linux kernel kbuild framework. However, if needed we can add checks for *.dtbo generation too as a follow up patch.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/scr...
-Sumit
Thanks, Michal