On Thu, Dec 28, 2023 at 4:59 AM Sumit Garg sumit.garg@linaro.org wrote:
Encourage SoC/board maintainers to migrate to using devicetree-rebasing subtree and maintain a regular sync with Linux kernel devicetree files and bindings.
Along with that add documentation regarding how to run DT bindings schema checks.
Signed-off-by: Sumit Garg sumit.garg@linaro.org
Changes in v3:
- Replace CONFIG_* with Kconfig options
Changes in v2:
- s/U-boot/U-Boot/
doc/develop/devicetree/control.rst | 131 +++++++++++++++++++++-------- 1 file changed, 96 insertions(+), 35 deletions(-)
diff --git a/doc/develop/devicetree/control.rst b/doc/develop/devicetree/control.rst index cbb65c9b177..65180d33e8d 100644 --- a/doc/develop/devicetree/control.rst +++ b/doc/develop/devicetree/control.rst @@ -1,5 +1,6 @@ .. SPDX-License-Identifier: GPL-2.0+ .. sectionauthor:: Copyright 2011 The Chromium OS Authors +.. Copyright 2023 Linaro Ltd.
Devicetree Control in U-Boot
@@ -22,14 +23,13 @@ for three reasons: hierarchical format
- It is fairly efficient to read incrementally
-The arch/<arch>/dts directories contains a Makefile for building the devicetree -blob and embedding it in the U-Boot image. This is useful since it allows -U-Boot to configure itself according to what it finds there. If you have -a number of similar boards with different peripherals, you can describe -the features of each board in the devicetree file, and have a single -generic source base. +The U-Boot Makefile infrastructure allows for building the devicetree blob +and embedding it in the U-Boot image. This is useful since it allows U-Boot +to configure itself according to what it finds there. If you have a number +of similar boards with different peripherals, you can describe the features +of each board in the devicetree file, and have a single generic source base.
-To enable this feature, add CONFIG_OF_CONTROL to your board config file. +To enable this feature, select `OF_CONTROL` via Kconfig.
What is a Flattened Devicetree? @@ -68,8 +68,21 @@ a binary file. U-Boot adds its own `fdtgrep` for creating subsets of the file. Where do I get a devicetree file for my board?
-You may find that the Linux kernel has a suitable file. Look in the -kernel source in arch/<arch>/boot/dts. +Linux kernel Git repository has been the place where devicetree files along +with devicetree bindings are stored and maintained. There is devicetee-rebasing +(dtrepo_) which maintains a forked copy of devicetree files along with bindings +at every Linux kernel major release or intermideate release candidates.
Typo.
+In order to maintain devicetree files sync, U-Boot maintains a Git subtree for +devicetee-rebasing repo as `devicetee-rebasing/` sub-directory. It is regularly +kept updated with every new kernel major release via subtree pull as follows::
I would suggest dropping "-rebasing" in the u-boot tree. (I wish we had in the original repo). I don't think it's relevant.
We're not likely to regenerate the tree, but any clue what 'git subtree pull' would do in this case? It could happen if we switched to git-filter-repo.
- git subtree pull --prefix devicetree-rebasing \
git://git.kernel.org/pub/scm/linux/kernel/git/devicetree/devicetree-rebasing.git \<release-tag> --squash
I'd put this in a script to run. Documentation tends to be not quite correct. A script could also be smarter and figure out <release-tag>.
+You may find that the `devicetee-rebasing/` sub-directory has a suitable +devicetree file for your board. Look in `devicetree-rebasing/src/<arch>/`.