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Linux kernel mirror (for testing)
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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 Few subsystems, like ASoC, media, regulators and SPI, expect reverse order
19 of the prefixes::
20
21 "<binding dir>: dt-bindings: ..."
22
23 The 80 characters of the subject are precious. It is recommended to not
24 use "Documentation", "doc" or "YAML" because that is implied. All
25 bindings are docs and all new bindings are supposed to be in Devicetree
26 schema format. Repeating "binding" again should also be avoided, so for
27 a new device it is often enough for example::
28
29 "dt-bindings: iio: adc: Add ROHM BD79100G"
30
31 Conversion of other formats to DT schema::
32
33 "dt-bindings: iio: adc: adi,ad7476: Convert to DT schema"
34
35 2) DT binding files are written in DT schema format using json-schema
36 vocabulary and YAML file format. The DT binding files must pass validation
37 by running::
38
39 make dt_binding_check
40
41 See Documentation/devicetree/bindings/writing-schema.rst for more details
42 about schema and tools setup.
43
44 3) DT binding files should be dual licensed. The preferred license tag is
45 (GPL-2.0-only OR BSD-2-Clause).
46
47 4) Submit the entire series to the devicetree mailinglist at
48
49 devicetree@vger.kernel.org
50
51 and Cc: the DT maintainers. Use scripts/get_maintainer.pl to identify
52 all of the DT maintainers.
53
54 5) The Documentation/ portion of the patch should come in the series before
55 the code implementing the binding.
56
57 6) Any compatible strings used in a chip or board DTS file must be
58 previously documented in the corresponding DT binding file
59 in Documentation/devicetree/bindings. This rule applies even if
60 the Linux device driver does not yet match on the compatible
61 string. [ checkpatch will emit warnings if this step is not
62 followed as of commit bff5da4335256513497cc8c79f9a9d1665e09864
63 ("checkpatch: add DT compatible string documentation checks"). ]
64
65 7) DTS is treated in general as driver-independent hardware description, thus
66 any DTS patches, regardless whether using existing or new bindings, should
67 be placed at the end of patchset to indicate no dependency of drivers on
68 the DTS. DTS will be anyway applied through separate tree or branch, so
69 different order would indicate the series is non-bisectable.
70
71 If a driver subsystem maintainer prefers to apply entire set, instead of
72 their relevant portion of patchset, please split the DTS patches into
73 separate patchset with a reference in changelog or cover letter to the
74 bindings submission on the mailing list.
75
76 8) If a documented compatible string is not yet matched by the
77 driver, the documentation should also include a compatible
78 string that is matched by the driver.
79
80 9) Bindings are actively used by multiple projects other than the Linux
81 Kernel, extra care and consideration may need to be taken when making changes
82 to existing bindings.
83
84II. For kernel maintainers
85==========================
86
87 1) If you aren't comfortable reviewing a given binding, reply to it and ask
88 the devicetree maintainers for guidance. This will help them prioritize
89 which ones to review and which ones are ok to let go.
90
91 2) For driver (not subsystem) bindings: If you are comfortable with the
92 binding, and it hasn't received an Acked-by from the devicetree
93 maintainers after a few weeks, go ahead and take it.
94
95 For subsystem bindings (anything affecting more than a single device),
96 getting a devicetree maintainer to review it is required.
97
98 3) For a series going through multiple trees, the binding patch should be
99 kept with the driver using the binding.
100
101 4) The DTS files should however never be applied via driver subsystem tree,
102 but always via platform SoC trees on dedicated branches (see also
103 Documentation/process/maintainer-soc.rst).
104
105III. Notes
106==========
107
108 0) Please see Documentation/devicetree/bindings/ABI.rst for details
109 regarding devicetree ABI.
110
111 1) This document is intended as a general familiarization with the process as
112 decided at the 2013 Kernel Summit. When in doubt, the current word of the
113 devicetree maintainers overrules this document. In that situation, a patch
114 updating this document would be appreciated.