Commit 4dd23a47 authored by Sam Ravnborg's avatar Sam Ravnborg
Browse files

dt-bindings: display: convert display-timings to DT schema 



Add display-timings.yaml - that references panel-timings.yaml.
display-timings.yaml will be used for display bindings
when they are converted to meta-schema format.

For now the old display-timing.txt points to the new
display-timings.yaml - and all users are left as-is.

v2:
  - Updated native-mode description

v3:
  - Simpler "^timing" pattern (Rob)
  - timing node is of type object (Rob)
  - added display-timings to panel-common.yaml
  - added yaml document terminator "..."

Signed-off-by: default avatarSam Ravnborg <sam@ravnborg.org>
Reviewed-by: default avatarRob Herring <robh@kernel.org>
Acked-by: default avatarMaxime Ripard <mripard@kernel.org>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
Cc: devicetree@vger.kernel.org
Link: https://patchwork.freedesktop.org/patch/msgid/20200216181513.28109-3-sam@ravnborg.org
parent 3aa31ced

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

+1 −123
Original line number Diff line number Diff line 
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>;

	};
 
See display-timings.yaml in this directory.

Documentation/devicetree/bindings/display/panel/display-timings.yaml

0 → 100644
+77 −0
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# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)

%YAML 1.2

---

$id: http://devicetree.org/schemas/display/panel/display-timings.yaml#

$schema: http://devicetree.org/meta-schemas/core.yaml#



title: display timing bindings



maintainers:

  - Thierry Reding <thierry.reding@gmail.com>

  - Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

  - Sam Ravnborg <sam@ravnborg.org>



description: |

  A display panel may be able to handle several display timings,

  with different resolutions.

  The display-timings node makes it possible to specify the timing

  and to specify the timing that is native for the display.



properties:

  $nodename:

    const: display-timings



  native-mode:

    $ref: /schemas/types.yaml#/definitions/phandle

    description: |

      The default display timing is the one specified as native-mode.

      If no native-mode is specified then the first node is assumed the

      native mode.



patternProperties:

  "^timing":

    type: object

    allOf:

      - $ref: panel-timing.yaml#



additionalProperties: false



examples:

  - |+



    /*

     * Example that specifies panel timing using minimum, typical,

     * maximum values as commonly used in datasheet description.

     * timing1 is the native-mode.

     */

    display-timings {

        native-mode = <&timing1>;

        timing0 {

            /* 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>;

        };

        timing1 {

            /* 1920x1080p24 */

            clock-frequency = <52000000>;

            hactive = <1920>;

            vactive = <1080>;

            hfront-porch = <25>;

            hback-porch = <25>;

            hsync-len = <0 25 25>;

            vback-porch = <2>;

            vfront-porch = <2>;

            vsync-len = <2>;

            hsync-active = <1>;

            pixelclk-active = <1>;

        };

    };



...

Documentation/devicetree/bindings/display/panel/panel-common.yaml

+8 −0
Original line number Diff line number Diff line
@@ -61,6 +61,14 @@ properties: 
    allOf:

      - $ref: panel-timing.yaml#



  display-timings:

    description:

      Some display panels supports several resolutions with different timing.

      The display-timings bindings supports specifying several timings and

      optional specify which is the native mode.

    allOf:

      - $ref: display-timings.yaml#



  # Connectivity

  port:

    type: object

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