display-timing bindings
display-timings node
required properties:
- none
optional properties:
- native-mode: The native mode for the display, in case multiple modes are
provided. When omitted, assume the first node is the native.
timing subnode
required properties:
- hactive, vactive: display resolution
- hfront-porch, hback-porch, hsync-len: horizontal display timing parameters
in pixels
vfront-porch, vback-porch, vsync-len: vertical display timing parameters in
lines - clock-frequency: display clock in Hz
optional properties:
- hsync-active: hsync pulse is active low/high/ignored
- vsync-active: vsync pulse is active low/high/ignored
- de-active: data-enable pulse is active low/high/ignored
- pixelclk-active: with
- active high = drive pixel data on rising edge/ sample data on falling edge - active low = drive pixel data on falling edge/ sample data on rising edge - ignored = ignored - syncclk-active: with
- active high = drive sync on rising edge/ sample sync on falling edge of pixel clock - active low = drive sync on falling edge/ sample sync on rising edge of pixel clock - omitted = same configuration as pixelclk-active - interlaced (bool): boolean to enable interlaced mode
- doublescan (bool): boolean to enable doublescan mode
- doubleclk (bool): boolean to enable doubleclock mode
All the optional properties that are not bool follow the following logic:
<1>: high active
<0>: low active
omitted: not used on hardware
There are different ways of describing the capabilities of a display. The
devicetree representation corresponds to the one commonly found in datasheets
for displays. If a display supports multiple signal timings, the native-mode
can be specified.
The parameters are defined as:
+———-+————————————-+———-+——-+
| | ^ | | |
| | |vback_porch | | |
| | v | | |
+———-#######################################———-+——-+
| # ^ # | |
| # | # | |
| hback # | # hfront | hsync |
| porch # | hactive # porch | len |
|<——–>#<——-+—————————>#<——–>|<—–>|
| # | # | |
| # |vactive # | |
| # | # | |
| # v # | |
+———-#######################################———-+——-+
| | ^ | | |
| | |vfront_porch | | |
| | v | | |
+———-+————————————-+———-+——-+
| | ^ | | |
| | |vsync_len | | |
| | v | | |
+———-+————————————-+———-+——-+
Note: In addition to being used as subnode(s) of display-timings, the timing
subnode may also be used on its own. This is appropriate if only one mode
need be conveyed. In this case, the node should be named ‘panel-timing’.
Example:
display-timings {
native-mode = <&timing0>;
timing0: 1080p24 {
/* 1920x1080p24 */
clock-frequency = <52000000>;
hactive = <1920>;
vactive = <1080>;
hfront-porch = <25>;
hback-porch = <25>;
hsync-len = <25>;
vback-porch = <2>;
vfront-porch = <2>;
vsync-len = <2>;
hsync-active = <1>;
};
};
Every required property also supports the use of ranges, so the commonly used
datasheet description with minimum, typical and maximum values can be used.
Example:
timing1: timing {
/* 1920x1080p24 */
clock-frequency = <148500000>;
hactive = <1920>;
vactive = <1080>;
hsync-len = <0 44 60>;
hfront-porch = <80 88 95>;
hback-porch = <100 148 160>;
vfront-porch = <0 4 6>;
vback-porch = <0 36 50>;
vsync-len = <0 5 6>;
};
