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Some MIPI DBI panels support a three wire mode (clock, chip select, bidirectional data) that can be used to ask the panel if it is already set up by e.g. the bootloader and can thus skip the initialization. This enables a flicker-free boot. Signed-off-by: Leonard Göhrs <l.goehrs@pengutronix.de> Acked-by: Conor Dooley <conor.dooley@microchip.com> Reviewed-by: Rob Herring <robh@kernel.org> Reviewed-by: Noralf Trønnes <noralf@tronnes.org> Link: https://lore.kernel.org/r/20230614123222.4167460-4-l.goehrs@pengutronix.de Signed-off-by: Rob Herring <robh@kernel.org>
138 lines
3.9 KiB
YAML
138 lines
3.9 KiB
YAML
# SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
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%YAML 1.2
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---
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$id: http://devicetree.org/schemas/display/panel/panel-mipi-dbi-spi.yaml#
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$schema: http://devicetree.org/meta-schemas/core.yaml#
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title: MIPI DBI SPI Panel
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maintainers:
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- Noralf Trønnes <noralf@tronnes.org>
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description: |
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This binding is for display panels using a MIPI DBI compatible controller
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in SPI mode.
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The MIPI Alliance Standard for Display Bus Interface defines the electrical
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and logical interfaces for display controllers historically used in mobile
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phones. The standard defines 4 display architecture types and this binding is
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for type 1 which has full frame memory. There are 3 interface types in the
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standard and type C is the serial interface.
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The standard defines the following interface signals for type C:
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- Power:
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- Vdd: Power supply for display module
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Called power-supply in this binding.
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- Vddi: Logic level supply for interface signals
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Called io-supply in this binding.
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- Interface:
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- CSx: Chip select
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- SCL: Serial clock
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- Dout: Serial out
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- Din: Serial in
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- SDA: Bidrectional in/out
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- D/CX: Data/command selection, high=data, low=command
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Called dc-gpios in this binding.
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- RESX: Reset when low
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Called reset-gpios in this binding.
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The type C interface has 3 options:
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- Option 1: 9-bit mode and D/CX as the 9th bit
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| Command | the next command or following data |
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|<0><D7><D6><D5><D4><D3><D2><D1><D0>|<D/CX><D7><D6><D5><D4><D3><D2><D1><D0>|
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- Option 2: 16-bit mode and D/CX as a 9th bit
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| Command or data |
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|<X><X><X><X><X><X><X><D/CX><D7><D6><D5><D4><D3><D2><D1><D0>|
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- Option 3: 8-bit mode and D/CX as a separate interface line
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| Command or data |
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|<D7><D6><D5><D4><D3><D2><D1><D0>|
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The panel resolution is specified using the panel-timing node properties
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hactive (width) and vactive (height). The other mandatory panel-timing
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properties should be set to zero except clock-frequency which can be
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optionally set to inform about the actual pixel clock frequency.
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If the panel is wired to the controller at an offset specify this using
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hback-porch (x-offset) and vback-porch (y-offset).
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allOf:
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- $ref: panel-common.yaml#
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- $ref: /schemas/spi/spi-peripheral-props.yaml#
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properties:
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compatible:
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items:
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- enum:
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- sainsmart18
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- shineworld,lh133k
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- const: panel-mipi-dbi-spi
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write-only:
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type: boolean
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description:
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Controller is not readable (ie. Din (MISO on the SPI interface) is not
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wired up).
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dc-gpios:
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maxItems: 1
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description: |
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Controller data/command selection (D/CX) in 4-line SPI mode.
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If not set, the controller is in 3-line SPI mode.
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io-supply:
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description: |
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Logic level supply for interface signals (Vddi).
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No need to set if this is the same as power-supply.
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spi-3wire: true
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required:
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- compatible
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- reg
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- width-mm
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- height-mm
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- panel-timing
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unevaluatedProperties: false
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examples:
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- |
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#include <dt-bindings/gpio/gpio.h>
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spi {
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#address-cells = <1>;
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#size-cells = <0>;
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display@0{
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compatible = "sainsmart18", "panel-mipi-dbi-spi";
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reg = <0>;
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spi-max-frequency = <40000000>;
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dc-gpios = <&gpio 24 GPIO_ACTIVE_HIGH>;
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reset-gpios = <&gpio 25 GPIO_ACTIVE_HIGH>;
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write-only;
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backlight = <&backlight>;
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width-mm = <35>;
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height-mm = <28>;
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panel-timing {
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hactive = <160>;
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vactive = <128>;
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hback-porch = <0>;
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vback-porch = <0>;
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clock-frequency = <0>;
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hfront-porch = <0>;
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hsync-len = <0>;
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vfront-porch = <0>;
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vsync-len = <0>;
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};
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};
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};
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...
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