1 .. SPDX-License-Identifier: GPL-2.0
2
3 ==============================================
4 DOs and DON'Ts for designing and writing Devic
5 ==============================================
6
7 This is a list of common review feedback items
8 every rule, there are exceptions and bindings
9
10 For guidelines related to patches, see
11 Documentation/devicetree/bindings/submitting-p
12
13
14 Overall design
15 ==============
16
17 - DO attempt to make bindings complete even if
18 features. For example, if a device has an in
19 'interrupts' property even if the driver is
20
21 - DON'T refer to Linux or "device driver" in b
22 based on what the hardware has, not what an
23
24 - DO use node names matching the class of the
25 defined in the DT Spec. If there isn't one,
26
27 - DO check that the example matches the docume
28 review changes.
29
30 - DON'T create nodes just for the sake of inst
31 devices only need child nodes when the child
32 resources. A single node can be multiple pro
33
34 - DON'T use 'syscon' alone without a specific
35 hardware block should have a compatible stri
36 register layout of the entire block (at a mi
37
38
39 Properties
40 ==========
41
42 - DO make 'compatible' properties specific. DO
43 strings. DO use fallback compatibles when de
44 of prior implementations. DO add new compati
45 features or bugs.
46
47 - DO use a vendor prefix on device-specific pr
48 properties could be common among devices of
49 existing bindings for similar devices.
50
51 - DON'T redefine common properties. Just refer
52 constraints specific to the device.
53
54 - DO use common property unit suffixes for pro
55 Recommended suffixes are listed at
56 https://github.com/devicetree-org/dt-schema/
57
58 - DO define properties in terms of constraints
59 possible values? What is the order?
60
61 Typical cases and caveats
62 =========================
63
64 - Phandle entries, like clocks/dmas/interrupts
65 explicitly ordered. Include the {clock,dma,i
66 more than one phandle. When used, both of th
67 constraints (e.g. list of items).
68
69 - For names used in {clock,dma,interrupt,reset
70 e.g.: "tx" instead of "txirq" (for interrupt
71
72 - Properties without schema types (e.g. withou
73 by schema) need the type, even if this is an
74
75 - If schema includes other schema (e.g. /schem
76 "unevaluatedProperties:false". In other case
77 "additionalProperties:false".
78
79 - For sub-blocks/components of bigger device (
80 device-based compatible (e.g. SoC-based comp
81 versioning of that component.
82 For example use "vendor,soc1234-i2c" instead
83
84 - "syscon" is not a generic property. Use vend
85 "vendor,power-manager-syscon".
86
87 Board/SoC .dts Files
88 ====================
89
90 - DO put all MMIO devices under a bus node and
91
92 - DO use non-empty 'ranges' to limit the size
93 platforms don't need all devices to have 64-
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