1.. SPDX-License-Identifier: GPL-2.0
2
3==========================================
4Submitting Devicetree (DT) binding patches
5==========================================
6
7I. For patch submitters
8=======================
9
10  0) Normal patch submission rules from
11     Documentation/process/submitting-patches.rst applies.
12
13  1) The Documentation/ and include/dt-bindings/ portion of the patch should
14     be a separate patch. The preferred subject prefix for binding patches is::
15
16       "dt-bindings: <binding dir>: ..."
17
18     The 80 characters of the subject are precious. It is recommended to not
19     use "Documentation" or "doc" because that is implied. All bindings are
20     docs. Repeating "binding" again should also be avoided.
21
22  2) DT binding files are written in DT schema format using json-schema
23     vocabulary and YAML file format. The DT binding files must pass validation
24     by running::
25
26       make dt_binding_check
27
28     See Documentation/devicetree/bindings/writing-schema.rst for more details
29     about schema and tools setup.
30
31  3) DT binding files should be dual licensed. The preferred license tag is
32     (GPL-2.0-only OR BSD-2-Clause).
33
34  4) Submit the entire series to the devicetree mailinglist at
35
36       devicetree@vger.kernel.org
37
38     and Cc: the DT maintainers. Use scripts/get_maintainer.pl to identify
39     all of the DT maintainers.
40
41  5) The Documentation/ portion of the patch should come in the series before
42     the code implementing the binding.
43
44  6) Any compatible strings used in a chip or board DTS file must be
45     previously documented in the corresponding DT binding text file
46     in Documentation/devicetree/bindings.  This rule applies even if
47     the Linux device driver does not yet match on the compatible
48     string.  [ checkpatch will emit warnings if this step is not
49     followed as of commit bff5da4335256513497cc8c79f9a9d1665e09864
50     ("checkpatch: add DT compatible string documentation checks"). ]
51
52  7) The wildcard "<chip>" may be used in compatible strings, as in
53     the following example:
54
55         - compatible: Must contain '"nvidia,<chip>-pcie",
56           "nvidia,tegra20-pcie"' where <chip> is tegra30, tegra132, ...
57
58     As in the above example, the known values of "<chip>" should be
59     documented if it is used.
60
61  8) If a documented compatible string is not yet matched by the
62     driver, the documentation should also include a compatible
63     string that is matched by the driver (as in the "nvidia,tegra20-pcie"
64     example above).
65
66  9) Bindings are actively used by multiple projects other than the Linux
67     Kernel, extra care and consideration may need to be taken when making changes
68     to existing bindings.
69
70II. For kernel maintainers
71==========================
72
73  1) If you aren't comfortable reviewing a given binding, reply to it and ask
74     the devicetree maintainers for guidance.  This will help them prioritize
75     which ones to review and which ones are ok to let go.
76
77  2) For driver (not subsystem) bindings: If you are comfortable with the
78     binding, and it hasn't received an Acked-by from the devicetree
79     maintainers after a few weeks, go ahead and take it.
80
81     For subsystem bindings (anything affecting more than a single device),
82     getting a devicetree maintainer to review it is required.
83
84  3) For a series going though multiple trees, the binding patch should be
85     kept with the driver using the binding.
86
87III. Notes
88==========
89
90  0) Please see Documentation/devicetree/bindings/ABI.rst for details
91     regarding devicetree ABI.
92
93  1) This document is intended as a general familiarization with the process as
94     decided at the 2013 Kernel Summit.  When in doubt, the current word of the
95     devicetree maintainers overrules this document.  In that situation, a patch
96     updating this document would be appreciated.
97