Documentation/process: maintainer-soc: add clean platforms profile

Some SoC platforms require that commits must not bring any new
dtbs_check warnings. Maintainers of such platforms usually have some
automation set, so any new warning will be spotted sooner or later.
Worst case: they run the tests themselves. Document requirements for
such platforms, so contributors can expect their patches being dropped
or ignored, if they bring new warnings for existing boards.

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Reviewed-by: Conor Dooley <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnd Bergmann <[e-mail]>

Documentation/process/maintainer-handbooks.rst

···
 
    maintainer-netdev
    maintainer-soc
+   maintainer-soc-clean-dts
    maintainer-tip
    maintainer-kvm-x86

Documentation/process/maintainer-soc-clean-dts.rst

···
+.. SPDX-License-Identifier: GPL-2.0
+
+==============================================
+SoC Platforms with DTS Compliance Requirements
+==============================================
+
+Overview
+--------
+
+SoC platforms or subarchitectures should follow all the rules from
+Documentation/process/maintainer-soc.rst.  This document referenced in
+MAINTAINERS impose additional requirements listed below.
+
+Strict DTS DT Schema and dtc Compliance
+---------------------------------------
+
+No changes to the SoC platform Devicetree sources (DTS files) should introduce
+new ``make dtbs_check W=1`` warnings.  Warnings in a new board DTS, which are
+results of issues in an included DTSI file, are considered existing, not new
+warnings.  The platform maintainers have automation in place which should point
+out any new warnings.
+
+If a commit introducing new warnings gets accepted somehow, the resulting
+issues shall be fixed in reasonable time (e.g. within one release) or the
+commit reverted.

MAINTAINERS

···
 P:	Documentation/process/maintainer-soc.rst
 C:	irc://irc.libera.chat/armlinux
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git
-F:	Documentation/process/maintainer-soc.rst
+F:	Documentation/process/maintainer-soc*.rst
 F:	arch/arm/boot/dts/Makefile
 F:	arch/arm64/boot/dts/Makefile