Devicetree and Open Firmware Subsystem

Other Process Documents

Please see the documents in Documentation/devicetree/bindings/ for information on how to write proper Devicetree bindings and how to submit patches.

Patch Review and Handling

Patches handled by Devicetree maintainers are processed differently depending on the patch type:

  1. Core OF driver code, e.g. drivers/of/: patches are reviewed and applied by DT maintainers.

  2. Devicetree bindings: patches are reviewed by DT maintainers, but should be applied by subsystem maintainers except in certain cases. See also For kernel maintainers in Submitting Devicetree (DT) binding patches.

  3. DTS and drivers: DT maintainers might provide comments, but review is generally not expected. DTS must pass schema checks (dtbs_check) or at least do not add any new warnings.

Patchwork

Devicetree maintainers review patches using Patchwork, so the current status of a patch can be checked there. For typical driver submissions, Patchwork receives the entire patch set, but only a few patches are usually Devicetree bindings that are reviewed by DT maintainers.

Explanation of Patchwork statuses:

  • New: Not yet processed by the automation toolset.

  • Needs ACK: Waiting for review by DT maintainers.

  • Handled Elsewhere: Non-DT patch; not being reviewed here.

  • RFC: Patch was likely ignored because it was an incomplete RFC.

  • Changes Requested: Patch was reviewed and DT maintainers expect changes.

  • Accepted: Patch was reviewed and applied by DT maintainers to their tree.

  • Not Applicable: Patch was reviewed and is likely in good shape, with a Reviewed-by or Acked-by tag provided, but DT maintainers expect someone else to apply it.

Patch Re-review and Pinging

Due to the high volume of email traffic, Devicetree maintainers do not read every email they receive and instead rely on Patchwork during the review process. They also often skip patches that have already been reviewed.

As a result, maintainers might miss:

  1. Questions about already reviewed patches.

  2. Pings, for example when a patch has been reviewed by DT maintainers but has not been picked up by subsystem maintainers.

Such cases can be addressed by:

  1. Pinging DT maintainers on the IRC channel.

  2. Dropping the DT maintainer’s Acked-by or Reviewed-by tag when sending a new version of the patch set, together with an explanation in the patch changelog describing why the tag was removed and what is expected from DT maintainers.