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    description:
58      Most display panels are restricted to a single resolution and
59      require specific display timings. The panel-timing subnode expresses those
60      timings.
61    allOf:
62      - $ref: panel-timing.yaml#
63
64  display-timings:
65    description:
66      Some display panels support several resolutions with different timings.
67      The display-timings bindings supports specifying several timings and
68      optionally specifying which is the native mode.
69    allOf:
70      - $ref: display-timings.yaml#
71
72  # Connectivity
73  port:
74    type: object
75
76  ports:
77    type: object
78    description:
79      Panels receive video data through one or multiple connections. While
80      the nature of those connections is specific to the panel type, the
81      connectivity is expressed in a standard fashion using ports as specified
82      in the device graph bindings defined in
83      Documentation/devicetree/bindings/graph.txt.
84
85  ddc-i2c-bus:
86    $ref: /schemas/types.yaml#/definitions/phandle
87    description:
88      Some panels expose EDID information through an I2C-compatible
89      bus such as DDC2 or E-DDC. For such panels the ddc-i2c-bus contains a
90      phandle to the system I2C controller connected to that bus.
91
92  no-hpd:
93    type: boolean
94    description:
95      This panel is supposed to communicate that it's ready via HPD
96      (hot plug detect) signal, but the signal isn't hooked up so we should
97      hardcode the max delay from the panel spec when powering up the panel.
98
99  hpd-gpios:
100    maxItems: 1
101    description:
102      If Hot Plug Detect (HPD) is connected to a GPIO in the system rather
103      than a dedicated HPD pin the pin can be specified here.
104
105  # Control I/Os
106
107  # Many display panels can be controlled through pins driven by GPIOs. The nature
108  # and timing of those control signals are device-specific and left for panel
109  # device tree bindings to specify. The following GPIO specifiers can however be
110  # used for panels that implement compatible control signals.
111
112  enable-gpios:
113    maxItems: 1
114    description: |
115      Specifier for a GPIO connected to the panel enable control signal. The
116      enable signal is active high and enables operation of the panel. This
117      property can also be used for panels implementing an active low power down
118      signal, which is a negated version of the enable signal. Active low enable
119      signals (or active high power down signals) can be supported by inverting
120      the GPIO specifier polarity flag.
121
122      Note that the enable signal control panel operation only and must not be
123      confused with a backlight enable signal.
124
125  reset-gpios:
126    maxItems: 1
127    description:
128      Specifier for a GPIO connected to the panel reset control signal.
129      The reset signal is active low and resets the panel internal logic
130      while active. Active high reset signals can be supported by inverting the
131      GPIO specifier polarity flag.
132
133  te-gpios:
134    maxItems: 1
135    description:
136      GPIO spec for the tearing effect synchronization signal.
137      The tearing effect signal is active high. Active low signals can be
138      supported by inverting the GPIO specifier polarity flag.
139
140  # Power
141  power-supply:
142    description:
143      Display panels require power to be supplied. While several panels need
144      more than one power supply with panel-specific constraints governing the
145      order and timings of the power supplies, in many cases a single power
146      supply is sufficient, either because the panel has a single power rail, or
147      because all its power rails can be driven by the same supply. In that case
148      the power-supply property specifies the supply powering the panel as a
149      phandle to a regulator.
150
151  # Backlight
152
153  # Most display panels include a backlight. Some of them also include a backlight
154  # controller exposed through a control bus such as I2C or DSI. Others expose
155  # backlight control through GPIO, PWM or other signals connected to an external
156  # backlight controller.
157
158  backlight:
159    $ref: /schemas/types.yaml#/definitions/phandle
160    description:
161      For panels whose backlight is controlled by an external backlight
162      controller, this property contains a phandle that references the
163      controller.
164
165dependencies:
166  width-mm: [ height-mm ]
167  height-mm: [ width-mm ]
168
169...
170