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