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
  38 All the optional properties that are not bool follow the following logic:
  39     <1>: high active
  40     <0>: low active
  41     omitted: not used on hardware
  42
  43 There are different ways of describing the capabilities of a display. The
  44 devicetree representation corresponds to the one commonly found in datasheets
  45 for displays. If a display supports multiple signal timings, the native-mode
  46 can be specified.
  47
  48 The parameters are defined as:
  49
  50   +----------+-------------------------------------+----------+-------+
  51   |          |        ↑                            |          |       |
  52   |          |        |vback_porch                 |          |       |
  53   |          |        ↓                            |          |       |
  54   +----------#######################################----------+-------+
  55   |          #        ↑                            #          |       |
  56   |          #        |                            #          |       |
  57   |  hback   #        |                            #  hfront  | hsync |
  58   |   porch  #        |       hactive              #  porch   |  len  |
  59   |<-------->#<-------+--------------------------->#<-------->|<----->|
  60   |          #        |                            #          |       |
  61   |          #        |vactive                     #          |       |
  62   |          #        |                            #          |       |
  63   |          #        ↓                            #          |       |
  64   +----------#######################################----------+-------+
  65   |          |        ↑                            |          |       |
  66   |          |        |vfront_porch                |          |       |
  67   |          |        ↓                            |          |       |
  68   +----------+-------------------------------------+----------+-------+
  69   |          |        ↑                            |          |       |
  70   |          |        |vsync_len                   |          |       |
  71   |          |        ↓                            |          |       |
  72   +----------+-------------------------------------+----------+-------+
  73
  74 Example:
  75
  76         display-timings {
  77                 native-mode = <&timing0>;
  78                 timing0: 1080p24 {
  79                         /* 1920x1080p24 */
  80                         clock-frequency = <52000000>;
  81                         hactive = <1920>;
  82                         vactive = <1080>;
  83                         hfront-porch = <25>;
  84                         hback-porch = <25>;
  85                         hsync-len = <25>;
  86                         vback-porch = <2>;
  87                         vfront-porch = <2>;
  88                         vsync-len = <2>;
  89                         hsync-active = <1>;
  90                 };
  91         };
  92
  93 Every required property also supports the use of ranges, so the commonly used
  94 datasheet description with minimum, typical and maximum values can be used.
  95
  96 Example:
  97
  98         timing1: timing {
  99                 /* 1920x1080p24 */
 100                 clock-frequency = <148500000>;
 101                 hactive = <1920>;
 102                 vactive = <1080>;
 103                 hsync-len = <0 44 60>;
 104                 hfront-porch = <80 88 95>;
 105                 hback-porch = <100 148 160>;
 106                 vfront-porch = <0 4 6>;
 107                 vback-porch = <0 36 50>;
 108                 vsync-len = <0 5 6>;
 109         };