Re: [PATCH 1/3] dt-bindings: display: add bindings for MIPI DBI compatible SPI panels

Den 24.01.2022 17.08, skrev Rob Herring:

On Sun, Jan 23, 2022 at 11:25 AM Noralf Trønnes noralf@tronnes.org wrote:

...

Add binding for MIPI DBI compatible SPI panels.

I'm sure we already have MIPI DBI panels. What's this for?

It aims to use one driver to cover all MIPI DBI panels where the controller setup is loaded from userspace in a firmware file. The cover letter points to the discussion where Maxime proposed this:

https://lore.kernel.org/dri-devel/20211129093946.xhp22mvdut3m67sc@houat/

Noralf.

...

Signed-off-by: Noralf Trønnes noralf@tronnes.org

.../display/panel/panel-mipi-dbi-spi.yaml | 69 +++++++++++++++++++ 1 file changed, 69 insertions(+) create mode 100644 Documentation/devicetree/bindings/display/panel/panel-mipi-dbi-spi.yaml

diff --git a/Documentation/devicetree/bindings/display/panel/panel-mipi-dbi-spi.yaml b/Documentation/devicetree/bindings/display/panel/panel-mipi-dbi-spi.yaml new file mode 100644 index 000000000000..d6c8accb045c --- /dev/null +++ b/Documentation/devicetree/bindings/display/panel/panel-mipi-dbi-spi.yaml @@ -0,0 +1,69 @@ +# SPDX-License-Identifier: GPL-2.0-only +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/display/panel/panel-mipi-dbi-spi.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml#

+title: MIPI DBI SPI Panels Device Tree Bindings

+maintainers:

• • Noralf Trønnes noralf@tronnes.org

+description:

• This binding is for display panels using a MIPI DBI controller
• in SPI mode.

+allOf:

• • $ref: panel/panel-common.yaml#
• • $ref: /schemas/spi/spi-peripheral-props.yaml#

+properties:

• compatible:
• const: panel-mipi-dbi-spi

Does the MIPI spec define how to power on a DBI panel with regulators, enable/reset lines, etc. and all the timing constraints between those? If not, then this compatible on its own is useless. It's fine as a fallback if it's presence means the panel uses only standard DBI commands and no vendor specific commands.

...

• model:
• $ref: /schemas/types.yaml#/definitions/string
• description: The name of the display panel.
• write-only:
• type: boolean
• description:

•  Controller is not readable (ie. MISO is not wired up).
  

• dc-gpios:
• maxItems: 1
• description: |

•  Controller data/command selection (D/CX) in 4-line SPI mode.
  

•  If not set, the controller is in 3-line SPI mode.
  

• backlight: true
• reg: true
• reset-gpios: true

+required:

• • compatible
• • model
• • reg

+additionalProperties: false

+examples:

• • |
• #include <dt-bindings/gpio/gpio.h>
• spi {

•        #address-cells = <1>;
  

•        #size-cells = <0>;
  

•        display@0{
  

•                compatible = "panel-mipi-dbi-spi";
  

•                model = "sainsmart18";
  

•                reg = <0>;
  

•                spi-max-frequency = <40000000>;
  

•                dc-gpios = <&gpio 24 GPIO_ACTIVE_HIGH>;
  

•                reset-gpios = <&gpio 25 GPIO_ACTIVE_HIGH>;
  

•                write-only;
  

•        };
  

• };

+...

2.33.0