Commit b0a5cde5 authored by Krzysztof Kozlowski's avatar Krzysztof Kozlowski Committed by Lee Jones
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dt-bindings: mfd: Explain lack of child dependency in simple-mfd 



Common mistake of usage of 'simple-mfd' compatible is a dependency of
children on resources acquired and managed by the parent, e.g. clocks.
Extend the simple-mfd documentation to cover this case.

Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarKrzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: default avatarConor Dooley <conor.dooley@microchip.com>
Reviewed-by: default avatarRob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20240623134600.115098-1-krzysztof.kozlowski@linaro.org


Signed-off-by: default avatarLee Jones <lee@kernel.org>
parent 1d845319

Documentation/devicetree/bindings/mfd/mfd.txt

+8 −7
Original line number Diff line number Diff line
@@ -17,13 +17,14 @@ A typical MFD can be: 


Optional properties:



- compatible : "simple-mfd" - this signifies that the operating system should

  consider all subnodes of the MFD device as separate devices akin to how

  "simple-bus" indicates when to see subnodes as children for a simple

  memory-mapped bus. For more complex devices, when the nexus driver has to

  probe registers to figure out what child devices exist etc, this should not

  be used. In the latter case the child devices will be determined by the

  operating system.

- compatible : "simple-mfd" - this signifies that the operating system

  should consider all subnodes of the MFD device as separate and independent

  devices, so not needing any resources to be provided by the parent device.

  Similarly to how "simple-bus" indicates when to see subnodes as children for

  a simple memory-mapped bus.

  For more complex devices, when the nexus driver has to probe registers to

  figure out what child devices exist etc, this should not be used. In the

  latter case the child devices will be determined by the operating system.



- ranges: Describes the address mapping relationship to the parent. Should set

  the child's base address to 0, the physical address within parent's address