Document properties common to several display panels in a central location that can be referenced by the panel device tree bindings. Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx> --- .../bindings/display/panel/panel-common.txt | 91 ++++++++++++++++++++++ 1 file changed, 91 insertions(+) create mode 100644 Documentation/devicetree/bindings/display/panel/panel-common.txt diff --git a/Documentation/devicetree/bindings/display/panel/panel-common.txt b/Documentation/devicetree/bindings/display/panel/panel-common.txt new file mode 100644 index 000000000000..ec52c472c845 --- /dev/null +++ b/Documentation/devicetree/bindings/display/panel/panel-common.txt @@ -0,0 +1,91 @@ +Common Properties for Display Panel +=================================== + +This document defines device tree properties common to several classes of +display panels. It doesn't constitue 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. + + +Descriptive Properties +---------------------- + +- width-mm, +- height-mm: The width-mm and height-mm specify the width and height of the + physical area where images are displayed. These properties are expressed in + millimeters and rounded to the closest unit. + +- label: 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. + + +Display Timings +--------------- + +- panel-timing: Most display panels are restricted to a single resolution and + require specific display timings. The panel-timing subnode expresses those + timings as specified in the timing subnode section of the display timing + bindings defined in + Documentation/devicetree/bindings/display/display-timing.txt. + + +Connectivity +------------ + +- ports: Panels receive video data through one or multiple connections. While + the nature of those connections is specific to the panel type, the + connectivity is expressed in a standard fashion using ports as specified in + the device graph bindings defined in + Documentation/devicetree/bindings/graph.txt. + +- ddc-i2c-bus: 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. + + +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: 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: Specifier for a GPIO coonnected 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. + + +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: For panels whose backlight is controlled by an external backlight + controller, this property contains a phandle that references the controller. -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
