Documentation/devicetree/bindings/video/display-timing.txt

   1 display-timing bindings
   2 =======================
   3
   4 display-timings node
   5 --------------------
   6
   7 required properties:
   8  - none
   9
  10 optional properties:
  11  - native-mode: The native mode for the display, in case multiple modes are
  12                 provided. When omitted, assume the first node is the native.
  13
  14 timing subnode
  15 --------------
  16
  17 required properties:
  18  - hactive, vactive: display resolution
  19  - hfront-porch, hback-porch, hsync-len: horizontal display timing parameters
  20    in pixels
  21    vfront-porch, vback-porch, vsync-len: vertical display timing parameters in
  22    lines
  23  - clock-frequency: display clock in Hz
  24
  25 optional properties:
  26  - hsync-active: hsync pulse is active low/high/ignored
  27  - vsync-active: vsync pulse is active low/high/ignored
  28  - de-active: data-enable pulse is active low/high/ignored
  29  - pixelclk-active: with
  30                         - active high = drive pixel data on rising edge/
  31                                         sample data on falling edge
  32                         - active low  = drive pixel data on falling edge/
  33                                         sample data on rising edge
  34                         - ignored     = ignored
  35  - interlaced (bool): boolean to enable interlaced mode
  36  - doublescan (bool): boolean to enable doublescan mode
  37  - doubleclk (bool): boolean to enable doubleclock mode
  38
  39 All the optional properties that are not bool follow the following logic:
  40     <1>: high active
  41     <0>: low active
  42     omitted: not used on hardware
  43
  44 There are different ways of describing the capabilities of a display. The
  45 devicetree representation corresponds to the one commonly found in datasheets
  46 for displays. If a display supports multiple signal timings, the native-mode
  47 can be specified.
  48
  49 The parameters are defined as:
  50
  51   +----------+-------------------------------------+----------+-------+
  52   |          |        ↑                            |          |       |
  53   |          |        |vback_porch                 |          |       |
  54   |          |        ↓                            |          |       |
  55   +----------#######################################----------+-------+
  56   |          #        ↑                            #          |       |
  57   |          #        |                            #          |       |
  58   |  hback   #        |                            #  hfront  | hsync |
  59   |   porch  #        |       hactive              #  porch   |  len  |
  60   |<-------->#<-------+--------------------------->#<-------->|<----->|
  61   |          #        |                            #          |       |
  62   |          #        |vactive                     #          |       |
  63   |          #        |                            #          |       |
  64   |          #        ↓                            #          |       |
  65   +----------#######################################----------+-------+
  66   |          |        ↑                            |          |       |
  67   |          |        |vfront_porch                |          |       |
  68   |          |        ↓                            |          |       |
  69   +----------+-------------------------------------+----------+-------+
  70   |          |        ↑                            |          |       |
  71   |          |        |vsync_len                   |          |       |
  72   |          |        ↓                            |          |       |
  73   +----------+-------------------------------------+----------+-------+
  74
  75 Example:
  76
  77         display-timings {
  78                 native-mode = <&timing0>;
  79                 timing0: 1080p24 {
  80                         /* 1920x1080p24 */
  81                         clock-frequency = <52000000>;
  82                         hactive = <1920>;
  83                         vactive = <1080>;
  84                         hfront-porch = <25>;
  85                         hback-porch = <25>;
  86                         hsync-len = <25>;
  87                         vback-porch = <2>;
  88                         vfront-porch = <2>;
  89                         vsync-len = <2>;
  90                         hsync-active = <1>;
  91                 };
  92         };
  93
  94 Every required property also supports the use of ranges, so the commonly used
  95 datasheet description with minimum, typical and maximum values can be used.
  96
  97 Example:
  98
  99         timing1: timing {
 100                 /* 1920x1080p24 */
 101                 clock-frequency = <148500000>;
 102                 hactive = <1920>;
 103                 vactive = <1080>;
 104                 hsync-len = <0 44 60>;
 105                 hfront-porch = <80 88 95>;
 106                 hback-porch = <100 148 160>;
 107                 vfront-porch = <0 4 6>;
 108                 vback-porch = <0 36 50>;
 109                 vsync-len = <0 5 6>;
 110         };