docs: dt: maintainer: Add Devicetree and OF maintainer profile document

Document how Devicetree and Open Firmware maintainers handle their
subsystem, especially focusing on two caveats:

Devicetree subsystem handles patches with a minor difference comparing
to other subsystems: while DT maintainers pick up OF code, they only
provide review of DT bindings without applying these.

All three DT bindings maintainers rely currently on Patchwork and due to
enormous amount of emails per day, regardless how much DT maintainers
try, they cannot read all the emails.

Cc: Rob Herring <robh@kernel.org>
Cc: Conor Dooley <conor+dt@kernel.org>
Cc: Saravana Kannan <saravanak@kernel.org>
Cc: devicetree@vger.kernel.org
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Link: https://patch.msgid.link/20260721060916.12465-2-krzysztof.kozlowski@oss.qualcomm.com
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>

Documentation/process/maintainer-devicetree.rst

@@ -0,0 +1,72 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+======================================
+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
+   Documentation/devicetree/bindings/submitting-patches.rst.
+
+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.
+

MAINTAINERS

@@ -20228,6 +20228,7 @@ S:	Maintained
 Q:	http://patchwork.kernel.org/project/devicetree/list/
 W:	http://www.devicetree.org/
 C:	irc://irc.libera.chat/devicetree
+P:	Documentation/process/maintainer-devicetree.rst
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git
 F:	Documentation/ABI/testing/sysfs-firmware-ofw
 F:	drivers/of/
@@ -20249,8 +20250,10 @@ L:	devicetree@vger.kernel.org
 S:	Maintained
 Q:	http://patchwork.kernel.org/project/devicetree/list/
 C:	irc://irc.libera.chat/devicetree
+P:	Documentation/process/maintainer-devicetree.rst
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git
 F:	Documentation/devicetree/
+F:	Documentation/process/maintainer-devicetree.rst
 F:	arch/*/boot/dts/
 F:	include/dt-bindings/