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