Re: [PATCH v3 0/2] Add capability to append to property

[Ayush Singh <ayush@beagleboard.org>]

On 11/11/24 15:24, Ayush Singh wrote:
> Allow appending values to a property instead of overriding the previous
> values of property.
> 
> Currently, we have /delete-node/ and /delete-property/, but lack
> /append-property/. Hence we end up having to repeat all existing values
> when appending to a property (e.g. see [1] appending to clocks from
> [2]).
> 
> This functionality is also important for creating a device tree based
> implementation to support different types of addon-boards such as
> mikroBUS, Grove [3], etc.
> 
> In practice, it looks as follows:
> 
> ```
> dts-v1/;
> 
> / {
> 	str-prop = "0";
> };
> 
> / {
> 	/append-property/ str-prop = "1";
> };
> ```
> 
> Open items
> - Appending to non-existent property:
> 
>    I think it is better to create a new property if the property does not
>    exist instead of giving an error.
>    If the default is an error, then the condition, "create a property if
>    it does not exist, else append" cannot be expressed. I think this
>    behaviour is desirable with more complex overlays required for
>    supporting addon boards using devicetree.
> 
> [3] https://lore.kernel.org/linux-arm-kernel/20240702164403.29067-1-afd@ti.com/
> [2] https://elixir.bootlin.com/linux/latest/source/arch/arm64/boot/dts/renesas/r8a77951-salvator-xs.dts#L39
> [1] https://elixir.bootlin.com/linux/latest/source/arch/arm64/boot/dts/renesas/r8a77951.dtsi#L3334
> 
> Signed-off-by: Ayush Singh <ayush@beagleboard.org>
> 
> ---
> Changes in v3:
> - Add support for annotations. Works similar to nodes (since they
>    already append by default).
> - Link to v2: https://lore.kernel.org/r/20240830-append-v2-0-ec1e03f110ad@beagleboard.org
> 
> Changes in v2:
> - Add comment for append struct member.
> - Small code improvements
> - Improve test
> - Link to v1: https://lore.kernel.org/r/20240827-append-v1-0-d7a126ef1be3@beagleboard.org
> 
> ---
> Ayush Singh (2):
>        dtc: Add /append-property/
>        tests: Add test for append-property
> 
>   dtc-lexer.l           |  7 +++++++
>   dtc-parser.y          |  6 ++++++
>   dtc.h                 |  5 +++++
>   livetree.c            | 36 +++++++++++++++++++++++++++++-------
>   tests/append_prop.dts | 21 +++++++++++++++++++++
>   tests/run_tests.sh    |  7 +++++++
>   6 files changed, 75 insertions(+), 7 deletions(-)
> ---
> base-commit: 99031e3a4a6e479466ae795790b44727434ca27d
> change-id: 20240827-append-f614fe3261f9
> 
> Best regards,

cc David Gibson <david@gibson.dropbear.id.au>

Sorry, forgot to tag you in this patch as well.


Ayush Singh