Re: [PATCH 2/6] dt-bindings/display: Add Solomon SSD16xx e-paper controller binding

[Rob Herring]

On Fri, May 01, 2026 at 12:03:07AM +0530, Devarsh Thakkar wrote:
> Add device tree binding for the Solomon Systech SSD16xx family of e-Paper
> display controllers (SSD1683 [1], SSD1673 [3], SSD1680 [4], SSD1681 [5]).
> 
> The binding covers the 4-wire SPI interface with required GPIO pins for
> reset (active-low), busy status (active-high), and data/command selection.
> The spi-max-frequency is capped at 20 MHz per the SSD1683 datasheet [1]
> which is also the maximum supported frequency amongst the family.
> 
> An optional rotation property allows static display orientation to be
> configured from device tree.
> 
> The data/command selection GPIO pin is also kept as optional since various
> SSD16XX controllers such as SSD1683 [1] support 3-wire mode too with
> data/command selection bit transmitted as first bit before sending the data
> sequence.
> 
> The first supported compatible is for Gooddisplay GDEY042T81 which is 4.2",
> 400x300 resolution black/white e-paper display using SSD1683 controller.
> 
> Links:
> [1] : https://www.crystalfontz.com/controllers/SolomonSystech/SSD1683
> [2] : https://files.seeedstudio.com/wiki/Other_Display/42-epaper/GDEY042T81.pdf
> [3] : https://www.crystalfontz.com/controllers/SolomonSystech/SSD1673
> [4] : https://www.crystalfontz.com/controllers/SolomonSystech/SSD1680
> [5] : https://www.crystalfontz.com/controllers/SolomonSystech/SSD1681
> 
> Signed-off-by: Devarsh Thakkar <devarsht@xxxxxx>
> ---
>  .../bindings/display/solomon,ssd16xx.yaml     | 81 +++++++++++++++++++
>  1 file changed, 81 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/display/solomon,ssd16xx.yaml
> 
> diff --git a/Documentation/devicetree/bindings/display/solomon,ssd16xx.yaml b/Documentation/devicetree/bindings/display/solomon,ssd16xx.yaml
> new file mode 100644
> index 000000000000..2433ddb859d6
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/solomon,ssd16xx.yaml
> @@ -0,0 +1,81 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/display/solomon,ssd16xx.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Solomon Systech SSD16xx controller based e-paper display panels
> +
> +maintainers:
> +  - Devarsh Thakkar <devarsht@xxxxxx>
> +
> +description:
> +  The SSD16xx family includes e-paper display controllers (SSD1680, SSD1681,
> +  SSD1673, SSD1683) with integrated gate driver, source driver and timing controller.
> +  Different panels use these controllers in monochrome or 3-color configurations.
> +  The controller uses a 4-wire SPI interface and requires GPIO pins for reset,
> +  busy status, and data/command control with a 3-wire mode also available
> +  where D/C bit is transmitted along the SPI data line before sending actual data.

Wrap lines at 80 chars.

> +
> +allOf:
> +  - $ref: /schemas/spi/spi-peripheral-props.yaml#
> +
> +properties:
> +  compatible:
> +    enum:
> +      - gooddisplay,gdey042t81  # 4.2" 400x300 monochrome (SSD1683 controller)

If you know the controller, make it a fallback compatible.

> +
> +  reg:
> +    maxItems: 1
> +
> +  spi-max-frequency:
> +    maximum: 20000000
> +
> +  reset-gpios:
> +    maxItems: 1
> +    description:
> +      GPIO connected to the RSTB (reset) pin. Active low.
> +
> +  busy-gpios:
> +    maxItems: 1
> +    description:
> +      GPIO connected to the BUSY pin. Active high when the controller is
> +      busy updating the display.
> +
> +  dc-gpios:
> +    maxItems: 1
> +    description:
> +      GPIO connected to the D/C (Data/Command) pin. Low for command, high
> +      for data.
> +
> +  rotation:
> +    enum: [0, 90, 180, 270]
> +    description:
> +      Display rotation in degrees counter clockwise (0,90,180,270)
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +
> +required:
> +  - compatible
> +  - reg
> +  - reset-gpios
> +  - busy-gpios
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    spi {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        display@0 {
> +            compatible = "gooddisplay,gdey042t81";
> +            reg = <0>;
> +            spi-max-frequency = <2000000>;
> +            reset-gpios = <&gpio1 17 GPIO_ACTIVE_LOW>;
> +            busy-gpios = <&gpio1 18 GPIO_ACTIVE_HIGH>;
> +            dc-gpios = <&gpio1 19 GPIO_ACTIVE_HIGH>;
> +        };
> +    };
> -- 
> 2.39.1
>