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 Documentation/process/submitting-patches.rst
11     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 ../writing-schema.rst for more details about schema and tools setup.
29
30  3) DT binding files should be dual licensed. The preferred license tag is
31     (GPL-2.0-only OR BSD-2-Clause).
32
33  4) Submit the entire series to the devicetree mailinglist at
34
35       devicetree@vger.kernel.org
36
37     and Cc: the DT maintainers. Use scripts/get_maintainer.pl to identify
38     all of the DT maintainers.
39
40  5) The Documentation/ portion of the patch should come in the series before
41     the code implementing the binding.
42
43  6) Any compatible strings used in a chip or board DTS file must be
44     previously documented in the corresponding DT binding text file
45     in Documentation/devicetree/bindings.  This rule applies even if
46     the Linux device driver does not yet match on the compatible
47     string.  [ checkpatch will emit warnings if this step is not
48     followed as of commit bff5da4335256513497cc8c79f9a9d1665e09864
49     ("checkpatch: add DT compatible string documentation checks"). ]
50
51  7) The wildcard "<chip>" may be used in compatible strings, as in
52     the following example:
53
54         - compatible: Must contain '"nvidia,<chip>-pcie",
55           "nvidia,tegra20-pcie"' where <chip> is tegra30, tegra132, ...
56
57     As in the above example, the known values of "<chip>" should be
58     documented if it is used.
59
60  8) If a documented compatible string is not yet matched by the
61     driver, the documentation should also include a compatible
62     string that is matched by the driver (as in the "nvidia,tegra20-pcie"
63     example above).
64
65
66II. For kernel maintainers
67==========================
68
69  1) If you aren't comfortable reviewing a given binding, reply to it and ask
70     the devicetree maintainers for guidance.  This will help them prioritize
71     which ones to review and which ones are ok to let go.
72
73  2) For driver (not subsystem) bindings: If you are comfortable with the
74     binding, and it hasn't received an Acked-by from the devicetree
75     maintainers after a few weeks, go ahead and take it.
76
77     Subsystem bindings (anything affecting more than a single device)
78     then getting a devicetree maintainer to review it is required.
79
80  3) For a series going though multiple trees, the binding patch should be
81     kept with the driver using the binding.
82
83III. Notes
84==========
85
86  0) Please see ...bindings/ABI.txt for details regarding devicetree ABI.
87
88  1) This document is intended as a general familiarization with the process as
89     decided at the 2013 Kernel Summit.  When in doubt, the current word of the
90     devicetree maintainers overrules this document.  In that situation, a patch
91     updating this document would be appreciated.
92