1# SPDX-License-Identifier: GPL-2.0
2%YAML 1.2
3---
4$id: http://devicetree.org/schemas/display/panel/panel-common.yaml#
5$schema: http://devicetree.org/meta-schemas/core.yaml#
6
7title: Common Properties for Display Panels
8
9maintainers:
10  - Thierry Reding <thierry.reding@gmail.com>
11  - Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
12
13description: |
14  This document defines device tree properties common to several classes of
15  display panels. It doesn't constitute a device tree binding specification by
16  itself but is meant to be referenced by device tree bindings.
17
18  When referenced from panel device tree bindings the properties defined in this
19  document are defined as follows. The panel device tree bindings are
20  responsible for defining whether each property is required or optional.
21
22properties:
23  # Descriptive Properties
24  width-mm:
25    description:
26      Specifies the width of the physical area where images are displayed. This
27      property is expressed in millimeters and rounded to the closest unit.
28
29  height-mm:
30    description:
31      Specifies the height of the physical area where images are displayed. This
32      property is expressed in millimeters and rounded to the closest unit.
33
34  label:
35    description: |
36      The label property specifies a symbolic name for the panel as a
37      string suitable for use by humans. It typically contains a name inscribed
38      on the system (e.g. as an affixed label) or specified in the system's
39      documentation (e.g. in the user's manual).
40
41      If no such name exists, and unless the property is mandatory according to
42      device tree bindings, it shall rather be omitted than constructed of
43      non-descriptive information. For instance an LCD panel in a system that
44      contains a single panel shall not be labelled "LCD" if that name is not
45      inscribed on the system or used in a descriptive fashion in system
46      documentation.
47
48  rotation:
49    description:
50      Display rotation in degrees counter clockwise (0,90,180,270)
51    $ref: /schemas/types.yaml#/definitions/uint32
52    enum: [0, 90, 180, 270]
53
54  # Display Timings
55  panel-timing:
56    description:
57      Most display panels are restricted to a single resolution and
58      require specific display timings. The panel-timing subnode expresses those
59      timings.
60    $ref: panel-timing.yaml#
61
62  display-timings:
63    description:
64      Some display panels support several resolutions with different timings.
65      The display-timings bindings supports specifying several timings and
66      optionally specifying which is the native mode.
67    $ref: display-timings.yaml#
68
69  # Connectivity
70  port:
71    $ref: /schemas/graph.yaml#/properties/port
72
73  ddc-i2c-bus:
74    $ref: /schemas/types.yaml#/definitions/phandle
75    description:
76      Some panels expose EDID information through an I2C-compatible
77      bus such as DDC2 or E-DDC. For such panels the ddc-i2c-bus contains a
78      phandle to the system I2C controller connected to that bus.
79
80  no-hpd:
81    type: boolean
82    description:
83      This panel is supposed to communicate that it's ready via HPD
84      (hot plug detect) signal, but the signal isn't hooked up so we should
85      hardcode the max delay from the panel spec when powering up the panel.
86
87  hpd-gpios:
88    maxItems: 1
89    description:
90      If Hot Plug Detect (HPD) is connected to a GPIO in the system rather
91      than a dedicated HPD pin the pin can be specified here.
92
93  # Control I/Os
94
95  # Many display panels can be controlled through pins driven by GPIOs. The nature
96  # and timing of those control signals are device-specific and left for panel
97  # device tree bindings to specify. The following GPIO specifiers can however be
98  # used for panels that implement compatible control signals.
99
100  enable-gpios:
101    maxItems: 1
102    description: |
103      Specifier for a GPIO connected to the panel enable control signal. The
104      enable signal is active high and enables operation of the panel. This
105      property can also be used for panels implementing an active low power down
106      signal, which is a negated version of the enable signal. Active low enable
107      signals (or active high power down signals) can be supported by inverting
108      the GPIO specifier polarity flag.
109
110      Note that the enable signal control panel operation only and must not be
111      confused with a backlight enable signal.
112
113  reset-gpios:
114    maxItems: 1
115    description:
116      Specifier for a GPIO connected to the panel reset control signal.
117      The reset signal is active low and resets the panel internal logic
118      while active. Active high reset signals can be supported by inverting the
119      GPIO specifier polarity flag.
120
121  te-gpios:
122    maxItems: 1
123    description:
124      GPIO spec for the tearing effect synchronization signal.
125      The tearing effect signal is active high. Active low signals can be
126      supported by inverting the GPIO specifier polarity flag.
127
128  # Power
129  power-supply:
130    description:
131      Display panels require power to be supplied. While several panels need
132      more than one power supply with panel-specific constraints governing the
133      order and timings of the power supplies, in many cases a single power
134      supply is sufficient, either because the panel has a single power rail, or
135      because all its power rails can be driven by the same supply. In that case
136      the power-supply property specifies the supply powering the panel as a
137      phandle to a regulator.
138
139  # Backlight
140
141  # Most display panels include a backlight. Some of them also include a backlight
142  # controller exposed through a control bus such as I2C or DSI. Others expose
143  # backlight control through GPIO, PWM or other signals connected to an external
144  # backlight controller.
145
146  backlight:
147    $ref: /schemas/types.yaml#/definitions/phandle
148    description:
149      For panels whose backlight is controlled by an external backlight
150      controller, this property contains a phandle that references the
151      controller.
152
153dependencies:
154  width-mm: [ height-mm ]
155  height-mm: [ width-mm ]
156
157additionalProperties: true
158
159...
160