# SPDX-License-Identifier: GPL-2.0
%YAML 1.2
---
$id: http://devicetree.org/schemas/display/panel/panel-common.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#
title: Common Properties for Display Panels
maintainers:
- Thierry Reding <[email protected]>
- Laurent Pinchart <[email protected]>
description: |
This document defines device tree properties common to several classes of
display panels. It doesn't constitute a device tree binding specification by
itself but is meant to be referenced by device tree bindings.
When referenced from panel device tree bindings the properties defined in this
document are defined as follows. The panel device tree bindings are
responsible for defining whether each property is required or optional.
properties:
# Descriptive Properties
width-mm:
description:
Specifies the width of the physical area where images are displayed. This
property is expressed in millimeters and rounded to the closest unit.
height-mm:
description:
Specifies the height of the physical area where images are displayed. This
property is expressed in millimeters and rounded to the closest unit.
label:
description: |
The label property specifies a symbolic name for the panel as a
string suitable for use by humans. It typically contains a name inscribed
on the system (e.g. as an affixed label) or specified in the system's
documentation (e.g. in the user's manual).
If no such name exists, and unless the property is mandatory according to
device tree bindings, it shall rather be omitted than constructed of
non-descriptive information. For instance an LCD panel in a system that
contains a single panel shall not be labelled "LCD" if that name is not
inscribed on the system or used in a descriptive fashion in system
documentation.
rotation:
description:
Display rotation in degrees counter clockwise (0,90,180,270)
$ref: /schemas/types.yaml#/definitions/uint32
enum: [0, 90, 180, 270]
# Display Timings
panel-timing:
description:
Most display panels are restricted to a single resolution and
require specific display timings. The panel-timing subnode expresses those
timings.
$ref: panel-timing.yaml#
display-timings:
description:
Some display panels support several resolutions with different timings.
The display-timings bindings supports specifying several timings and
optionally specifying which is the native mode.
$ref: display-timings.yaml#
# Connectivity
port:
$ref: /schemas/graph.yaml#/properties/port
ddc-i2c-bus:
$ref: /schemas/types.yaml#/definitions/phandle
description:
Some panels expose EDID information through an I2C-compatible
bus such as DDC2 or E-DDC. For such panels the ddc-i2c-bus contains a
phandle to the system I2C controller connected to that bus.
no-hpd:
type: boolean
description:
This panel is supposed to communicate that it's ready via HPD
(hot plug detect) signal, but the signal isn't hooked up so we should
hardcode the max delay from the panel spec when powering up the panel.
hpd-gpios:
maxItems: 1
description:
If Hot Plug Detect (HPD) is connected to a GPIO in the system rather
than a dedicated HPD pin the pin can be specified here.
# Control I/Os
# Many display panels can be controlled through pins driven by GPIOs. The nature
# and timing of those control signals are device-specific and left for panel
# device tree bindings to specify. The following GPIO specifiers can however be
# used for panels that implement compatible control signals.
enable-gpios:
maxItems: 1
description: |
Specifier for a GPIO connected to the panel enable control signal. The
enable signal is active high and enables operation of the panel. This
property can also be used for panels implementing an active low power down
signal, which is a negated version of the enable signal. Active low enable
signals (or active high power down signals) can be supported by inverting
the GPIO specifier polarity flag.
Note that the enable signal control panel operation only and must not be
confused with a backlight enable signal.
reset-gpios:
maxItems: 1
description:
Specifier for a GPIO connected to the panel reset control signal.
The reset signal is active low and resets the panel internal logic
while active. Active high reset signals can be supported by inverting the
GPIO specifier polarity flag.
te-gpios:
maxItems: 1
description:
GPIO spec for the tearing effect synchronization signal.
The tearing effect signal is active high. Active low signals can be
supported by inverting the GPIO specifier polarity flag.
# Power
power-supply:
description:
Display panels require power to be supplied. While several panels need
more than one power supply with panel-specific constraints governing the
order and timings of the power supplies, in many cases a single power
supply is sufficient, either because the panel has a single power rail, or
because all its power rails can be driven by the same supply. In that case
the power-supply property specifies the supply powering the panel as a
phandle to a regulator.
# Backlight
# Most display panels include a backlight. Some of them also include a backlight
# controller exposed through a control bus such as I2C or DSI. Others expose
# backlight control through GPIO, PWM or other signals connected to an external
# backlight controller.
backlight:
$ref: /schemas/types.yaml#/definitions/phandle
description:
For panels whose backlight is controlled by an external backlight
controller, this property contains a phandle that references the
controller.
dependencies:
width-mm: [ height-mm ]
height-mm: [ width-mm ]
additionalProperties: true
...
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