| # Upstream DT Overlays and TI kernel config fragments |
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| This is a repository for DT overlays and TI kernel config fragments. |
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| ## Branches |
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| `master` branch is the development branch and works with Linus' upstream `master` branch. |
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| When Linus tags a new kernel version, a branch will be created for that kernel version, e.g. `linux-5.7.y`. If stable releases for that kernel version will cause breakage with DT or configs, which is unlikely but possible, the patches can be added to `linux-5.7.y` to make it work with latest stable of that version. |
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| `ti-linux-x.y.z` branch is the development branch that works with the TI productized `ti-linux-x.y.z` kernel branch. When the kernel ti-linux branch is tagged this repo and branch will be tagged with the corresponding tag. |
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| Patches to the overlays should always be submitted to the `master` branch and if applicable back ported to the `ti-linux-x.y.z` branch. Only patches that are applicable to the `ti-linux-x.y.z` features should be submitted to that branch. |
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| ## DT Overlays |
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| The makefile does two things: |
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| - Compiles a pre-defined set of dts files with symbols enabled, taken from the kernel source tree |
| - Compiles DT overlays in this repository |
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| Linux directory can be given with `LINUX=dir`. If LINUX is undefined, Makefile will look for Linux directory from the current dir or `<projectdir>/../linux/` |
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| dtc compiler will be taken from `$LINUX/scripts/dtc/dtc` but can be overridden with DTC variable. Note that if you use dtc from the kernel directory, you need to have built it first (e.g. `make dtbs` in kernel). |
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| Output path can be given the same way as when building the kernel, with `O=dir` |
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| ARCH variable can be used to build a single arch instead of all, e.g. `ARCH=arm64` |
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| ## Testing DT Overlays |
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| The Makefile has `test` target which applies overlays to base dtb using `fdtapply` and reports if the apply succeeded. The Makefile has a list of base-dts + overlay-dtbos to define how to apply the overlays. |
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| This provides an easy way to test if overlays apply correctly. When adding new overlays, also add new test targets to the Makefile. |
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| ## Config fragments |
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| config directory contains defconfig_builder.sh. The Linux directory can be given with -k option. If Linux directory is not given, the script will look for Linux directory from the current dir or `<projectdir>/../linux/` |
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| ## Example developer workflow |
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| Linux sources in ~/work/linux and this project in ~/work/linux-dt |
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| ``` |
| $ cd ~/work/linux |
| $ ../linux-dt/config/defconfig_builder.sh |
| (select a defconfig) |
| $ make ti_sdk_dra7x_debug_defconfig |
| $ make |
| $ make -C ../linux-dt |
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| The symbol-enabled dtbs and dtbos are now under ~/work/linux-dt/arch/... |
| ``` |
