Re: [PATCH v3 0/3] pmdomain: core: add support for domain hierarchies in DT

On Tue, 21 Apr 2026 at 01:51, Kevin Hilman (TI) <[email protected]> wrote:
>
> Currently, PM domains can only support hierarchy for simple
> providers (e.g. ones with #power-domain-cells = 0).
>
> Add support for oncell providers as well by adding a new property
> `power-domains-child-ids` to describe the parent/child relationship.
>
> Also adds the first user of the new API: the Arm SCMI PM domain driver.
>
> Signed-off-by: Kevin Hilman (TI) <[email protected]>
> ---
> Changes in v3:
> - cleanup return codes for add_child_ids()
>   - < 0: error
>   - zero means no child domains present
>   - > 0: number of child domains added
> - arm_scmi: adopt to new return codes (only <0 is an error)
> - Link to v2: https://patch.msgid.link/20260410-topic-lpm-pmdomain-child-ids-v2-0-83396e4b5f8b@baylibre.com

The v3 series applied for next, thanks!

Kind regards
Uffe

>
> Changes compared to initial RFC[2]
> - dropped RFC
> - rewrote the parse/add function to use iterators/helpers from of.h
> - add a remove function for cleanup
> - use child domain language instead of subdomain
>
> This idea was previously discussed on the arm-scmi mailing list[1]
> where this approach was proposed by Ulf, and then an initial RFC[2]
> implementation was made.  From there, it was suggested by Rob[3] to
> use a nexus node map instead, which led to several more versions
> attempting to implement that, culminating in v5[4], where Rob and
> Geert then had second thoughts about the power-domain-map approach.
>
> Therefore, I've gone back to the approach in the initial RFC[2] to use
> the child-ids approach.
>
> [1] https://lore.kernel.org/arm-scmi/CAPDyKFo_P129sVirHHYjOQT+QUmpymcRJme9obzKJeRgO7B-1A@mail.gmail.com/
> [2] https://lore.kernel.org/all/20250528-pmdomain-hierarchy-onecell-v1-1-851780700c68@baylibre.com/
> [3] https://lore.kernel.org/all/[email protected]/
> [4] https://lore.kernel.org/r/20260122-pmdomain-hierarchy-onecell-v5-0-76855ec856bd@baylibre.com
>
> Changes in v2:
> - dt-bindings: fix warinings from make dt_binding_check
> - scmi_pm_domain: switch to dev_err()
> - pmdomain: core: fix locking around add/remove domains
> - pmdomain: error unwind if any children fail to be added
> - pmdomain: fix node reference leak
> - pmdomain: ensure power-domains and child-ids properties are same
>   length before iterating
> - Link to v1: https://patch.msgid.link/20260310-topic-lpm-pmdomain-child-ids-v1-0-5361687a18ff@baylibre.com
>
> ---
> Kevin Hilman (TI) (3):
>       dt-bindings: power: Add power-domains-child-ids property
>       pmdomain: core: add support for power-domains-child-ids
>       pmdomain: arm_scmi: add support for domain hierarchies
>
>  Documentation/devicetree/bindings/power/power-domain.yaml |  34 ++++++++++++++++++++++++++++++++++
>  drivers/pmdomain/arm/scmi_pm_domain.c                     |  14 +++++++++++++-
>  drivers/pmdomain/core.c                                   | 167 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/pm_domain.h                                 |  16 ++++++++++++++++
>  4 files changed, 230 insertions(+), 1 deletion(-)
> ---
> base-commit: f7b88edb52c8dd01b7e576390d658ae6eef0e134
> change-id: 20260310-topic-lpm-pmdomain-child-ids-e3d57ae57040
>
> Best regards,
> --
> Kevin Hilman (TI) <[email protected]>
>