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| author | Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> | 2025-08-18 15:25:35 +0200 |
|---|---|---|
| committer | Rob Herring (Arm) <robh@kernel.org> | 2025-09-03 09:01:25 -0500 |
| commit | 81bb4d07edd72a56180e2c8414ead0e63c379502 (patch) | |
| tree | f1446cc00ad01c20ff604b7b46d7f2d2f07826ef | |
| parent | 835bdddd028ff57afaee28eb5e4b260f714fd555 (diff) | |
| download | linux-81bb4d07edd72a56180e2c8414ead0e63c379502.tar.gz linux-81bb4d07edd72a56180e2c8414ead0e63c379502.zip | |
docs: dt: writing-bindings: Document node name ABI and simple-mfd
Document established Devicetree bindings maintainers review practice:
1. Device node names should not be treated as an ABI, unless for
children of a device when documented.
There were many patches posted using of_find_node_by_name() or
of_node_name_eq() for accessing siblings or completely different
nodes. These cases were introducing undocumented ABI, so they are
discouraged.
2. 'simple-mfd' means children do not depend on parent device resources.
'simple-bus' is so simple, that even 'reg' properties are not
applicable.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20250818132534.120217-2-krzysztof.kozlowski@linaro.org
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
| -rw-r--r-- | Documentation/devicetree/bindings/writing-bindings.rst | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/writing-bindings.rst b/Documentation/devicetree/bindings/writing-bindings.rst index f8e0293a7c06..667816dd7d50 100644 --- a/Documentation/devicetree/bindings/writing-bindings.rst +++ b/Documentation/devicetree/bindings/writing-bindings.rst @@ -31,10 +31,19 @@ Overall design devices only need child nodes when the child nodes have their own DT resources. A single node can be multiple providers (e.g. clocks and resets). +- DON'T treat device node names as a stable ABI, but instead use phandles or + compatibles to find sibling devices. Exception: sub-nodes of given device + could be treated as ABI, if explicitly documented in the bindings. + - DON'T use 'syscon' alone without a specific compatible string. A 'syscon' hardware block should have a compatible string unique enough to infer the register layout of the entire block (at a minimum). +- DON'T use 'simple-mfd' compatible for non-trivial devices, where children + depend on some resources from the parent. Similarly, 'simple-bus' should not + be used for complex buses and even 'regs' property means device is not + a simple bus. + Properties ========== |