1 Common Properties for Display Panel
2 ===================================
4 This document defines device tree properties common to several classes of
5 display panels. It doesn't constitue a device tree binding specification by
6 itself but is meant to be referenced by device tree bindings.
8 When referenced from panel device tree bindings the properties defined in this
9 document are defined as follows. The panel device tree bindings are
10 responsible for defining whether each property is required or optional.
13 Descriptive Properties
14 ----------------------
17 - height-mm: The width-mm and height-mm specify the width and height of the
18 physical area where images are displayed. These properties are expressed in
19 millimeters and rounded to the closest unit.
21 - label: The label property specifies a symbolic name for the panel as a
22 string suitable for use by humans. It typically contains a name inscribed on
23 the system (e.g. as an affixed label) or specified in the system's
24 documentation (e.g. in the user's manual).
26 If no such name exists, and unless the property is mandatory according to
27 device tree bindings, it shall rather be omitted than constructed of
28 non-descriptive information. For instance an LCD panel in a system that
29 contains a single panel shall not be labelled "LCD" if that name is not
30 inscribed on the system or used in a descriptive fashion in system
37 - panel-timing: Most display panels are restricted to a single resolution and
38 require specific display timings. The panel-timing subnode expresses those
39 timings as specified in the timing subnode section of the display timing
41 Documentation/devicetree/bindings/display/panel/display-timing.txt.
47 - ports: Panels receive video data through one or multiple connections. While
48 the nature of those connections is specific to the panel type, the
49 connectivity is expressed in a standard fashion using ports as specified in
50 the device graph bindings defined in
51 Documentation/devicetree/bindings/graph.txt.
53 - ddc-i2c-bus: Some panels expose EDID information through an I2C-compatible
54 bus such as DDC2 or E-DDC. For such panels the ddc-i2c-bus contains a
55 phandle to the system I2C controller connected to that bus.
61 Many display panels can be controlled through pins driven by GPIOs. The nature
62 and timing of those control signals are device-specific and left for panel
63 device tree bindings to specify. The following GPIO specifiers can however be
64 used for panels that implement compatible control signals.
66 - enable-gpios: Specifier for a GPIO connected to the panel enable control
67 signal. The enable signal is active high and enables operation of the panel.
68 This property can also be used for panels implementing an active low power
69 down signal, which is a negated version of the enable signal. Active low
70 enable signals (or active high power down signals) can be supported by
71 inverting the GPIO specifier polarity flag.
73 Note that the enable signal control panel operation only and must not be
74 confused with a backlight enable signal.
76 - reset-gpios: Specifier for a GPIO coonnected to the panel reset control
77 signal. The reset signal is active low and resets the panel internal logic
78 while active. Active high reset signals can be supported by inverting the
79 GPIO specifier polarity flag.
85 Most display panels include a backlight. Some of them also include a backlight
86 controller exposed through a control bus such as I2C or DSI. Others expose
87 backlight control through GPIO, PWM or other signals connected to an external
90 - backlight: For panels whose backlight is controlled by an external backlight
91 controller, this property contains a phandle that references the controller.