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    $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    type: object
72
73  ports:
74    type: object
75    description:
76      Panels receive video data through one or multiple connections. While
77      the nature of those connections is specific to the panel type, the
78      connectivity is expressed in a standard fashion using ports as specified
79      in the device graph bindings defined in
80      Documentation/devicetree/bindings/graph.txt.
81
82  ddc-i2c-bus:
83    $ref: /schemas/types.yaml#/definitions/phandle
84    description:
85      Some panels expose EDID information through an I2C-compatible
86      bus such as DDC2 or E-DDC. For such panels the ddc-i2c-bus contains a
87      phandle to the system I2C controller connected to that bus.
88
89  no-hpd:
90    type: boolean
91    description:
92      This panel is supposed to communicate that it's ready via HPD
93      (hot plug detect) signal, but the signal isn't hooked up so we should
94      hardcode the max delay from the panel spec when powering up the panel.
95
96  hpd-gpios:
97    maxItems: 1
98    description:
99      If Hot Plug Detect (HPD) is connected to a GPIO in the system rather
100      than a dedicated HPD pin the pin can be specified here.
101
102  # Control I/Os
103
104  # Many display panels can be controlled through pins driven by GPIOs. The nature
105  # and timing of those control signals are device-specific and left for panel
106  # device tree bindings to specify. The following GPIO specifiers can however be
107  # used for panels that implement compatible control signals.
108
109  enable-gpios:
110    maxItems: 1
111    description: |
112      Specifier for a GPIO connected to the panel enable control signal. The
113      enable signal is active high and enables operation of the panel. This
114      property can also be used for panels implementing an active low power down
115      signal, which is a negated version of the enable signal. Active low enable
116      signals (or active high power down signals) can be supported by inverting
117      the GPIO specifier polarity flag.
118
119      Note that the enable signal control panel operation only and must not be
120      confused with a backlight enable signal.
121
122  reset-gpios:
123    maxItems: 1
124    description:
125      Specifier for a GPIO connected to the panel reset control signal.
126      The reset signal is active low and resets the panel internal logic
127      while active. Active high reset signals can be supported by inverting the
128      GPIO specifier polarity flag.
129
130  te-gpios:
131    maxItems: 1
132    description:
133      GPIO spec for the tearing effect synchronization signal.
134      The tearing effect signal is active high. Active low signals can be
135      supported by inverting the GPIO specifier polarity flag.
136
137  # Power
138  power-supply:
139    description:
140      Display panels require power to be supplied. While several panels need
141      more than one power supply with panel-specific constraints governing the
142      order and timings of the power supplies, in many cases a single power
143      supply is sufficient, either because the panel has a single power rail, or
144      because all its power rails can be driven by the same supply. In that case
145      the power-supply property specifies the supply powering the panel as a
146      phandle to a regulator.
147
148  # Backlight
149
150  # Most display panels include a backlight. Some of them also include a backlight
151  # controller exposed through a control bus such as I2C or DSI. Others expose
152  # backlight control through GPIO, PWM or other signals connected to an external
153  # backlight controller.
154
155  backlight:
156    $ref: /schemas/types.yaml#/definitions/phandle
157    description:
158      For panels whose backlight is controlled by an external backlight
159      controller, this property contains a phandle that references the
160      controller.
161
162dependencies:
163  width-mm: [ height-mm ]
164  height-mm: [ width-mm ]
165
166...
167