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 constitue 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    allOf:
52      - $ref: /schemas/types.yaml#/definitions/uint32
53      - enum: [ 0, 90, 180, 270 ]
54
55  # Display Timings
56  panel-timing:
57    type: object
58    description:
59      Most display panels are restricted to a single resolution and
60      require specific display timings. The panel-timing subnode expresses those
61      timings as specified in the timing subnode section of the display timing
62      bindings defined in
63      Documentation/devicetree/bindings/display/panel/display-timing.txt.
64
65  # Connectivity
66  port:
67    type: object
68
69  ports:
70    type: object
71    description:
72      Panels receive video data through one or multiple connections. While
73      the nature of those connections is specific to the panel type, the
74      connectivity is expressed in a standard fashion using ports as specified
75      in the device graph bindings defined in
76      Documentation/devicetree/bindings/graph.txt.
77
78  ddc-i2c-bus:
79    $ref: /schemas/types.yaml#/definitions/phandle
80    description:
81      Some panels expose EDID information through an I2C-compatible
82      bus such as DDC2 or E-DDC. For such panels the ddc-i2c-bus contains a
83      phandle to the system I2C controller connected to that bus.
84
85  no-hpd:
86    type: boolean
87    description:
88      This panel is supposed to communicate that it's ready via HPD
89      (hot plug detect) signal, but the signal isn't hooked up so we should
90      hardcode the max delay from the panel spec when powering up the panel.
91
92  # Control I/Os
93
94  # Many display panels can be controlled through pins driven by GPIOs. The nature
95  # and timing of those control signals are device-specific and left for panel
96  # device tree bindings to specify. The following GPIO specifiers can however be
97  # used for panels that implement compatible control signals.
98
99  enable-gpios:
100    maxItems: 1
101    description: |
102      Specifier for a GPIO connected to the panel enable control signal. The
103      enable signal is active high and enables operation of the panel. This
104      property can also be used for panels implementing an active low power down
105      signal, which is a negated version of the enable signal. Active low enable
106      signals (or active high power down signals) can be supported by inverting
107      the GPIO specifier polarity flag.
108
109      Note that the enable signal control panel operation only and must not be
110      confused with a backlight enable signal.
111
112  reset-gpios:
113    maxItems: 1
114    description:
115      Specifier for a GPIO connected to the panel reset control signal.
116      The reset signal is active low and resets the panel internal logic
117      while active. Active high reset signals can be supported by inverting the
118      GPIO specifier polarity flag.
119
120  # Power
121  power-supply:
122    description:
123      Display panels require power to be supplied. While several panels need
124      more than one power supply with panel-specific constraints governing the
125      order and timings of the power supplies, in many cases a single power
126      supply is sufficient, either because the panel has a single power rail, or
127      because all its power rails can be driven by the same supply. In that case
128      the power-supply property specifies the supply powering the panel as a
129      phandle to a regulator.
130
131  # Backlight
132
133  # Most display panels include a backlight. Some of them also include a backlight
134  # controller exposed through a control bus such as I2C or DSI. Others expose
135  # backlight control through GPIO, PWM or other signals connected to an external
136  # backlight controller.
137
138  backlight:
139    $ref: /schemas/types.yaml#/definitions/phandle
140    description:
141      For panels whose backlight is controlled by an external backlight
142      controller, this property contains a phandle that references the
143      controller.
144
145dependencies:
146  width-mm: [ height-mm ]
147  height-mm: [ width-mm ]
148
149...
150