| Simon Glass | b24e864 | 2015-04-14 21:03:21 -0600 | [diff] [blame] | 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 | }; |