[v2] drm/sitronix/st7920: Add support for the ST7920 controller

[PATCH v2 2/3] dt-bindings: display: sitronix,st7920: Add DT schema

Posted by Iker Pedrosa 5 months ago

Add binding for Sitronix ST7920 display.

Signed-off-by: Iker Pedrosa <ikerpedrosam@gmail.com>
---
 .../bindings/display/sitronix,st7920.yaml          | 52 ++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/sitronix,st7920.yaml b/Documentation/devicetree/bindings/display/sitronix,st7920.yaml
new file mode 100644
index 0000000000000000000000000000000000000000..f08869c48a634cdb2a9e6fb33a0510cd1a407970
--- /dev/null
+++ b/Documentation/devicetree/bindings/display/sitronix,st7920.yaml
@@ -0,0 +1,52 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/sitronix,st7920.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Sitronix ST7920 LCD Display Controllers
+
+maintainers:
+  - Iker Pedrosa <ikerpedrosam@gmail.com>
+
+description:
+  The Sitronix ST7920 is a controller for monochrome dot-matrix graphical LCDs,
+  most commonly used for 128x64 pixel displays.
+
+properties:
+  compatible:
+    const: sitronix,st7920
+
+  reg:
+    description: The chip-select number for the device on the SPI bus.
+    maxItems: 1
+
+  spi-max-frequency:
+    maximum: 600000
+
+required:
+  - compatible
+  - reg
+  - spi-max-frequency
+
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    // Example: ST7920 connected to an SPI bus
+    #include <dt-bindings/gpio/gpio.h>
+
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        display@0 {
+            compatible = "sitronix,st7920";
+            reg = <0>;
+            spi-max-frequency = <600000>;
+            spi-cs-high;
+        };
+    };

-- 
2.51.0

Re: [PATCH v2 2/3] dt-bindings: display: sitronix,st7920: Add DT schema

Posted by Krzysztof Kozlowski 4 months, 4 weeks ago

On Tue, Sep 09, 2025 at 06:52:44PM +0200, Iker Pedrosa wrote:
> Add binding for Sitronix ST7920 display.
> 
> Signed-off-by: Iker Pedrosa <ikerpedrosam@gmail.com>
> ---
>  .../bindings/display/sitronix,st7920.yaml          | 52 ++++++++++++++++++++++
>  1 file changed, 52 insertions(+)
> 

Please organize the patch documenting compatible (DT bindings) before their user.
See also: https://elixir.bootlin.com/linux/v6.14-rc6/source/Documentation/devicetree/bindings/submitting-patches.rst#L46

...

> +  reg:
> +    description: The chip-select number for the device on the SPI bus.

Drop description, obvious/redundant.

> +    maxItems: 1
> +
> +  spi-max-frequency:
> +    maximum: 600000
> +

I don't see how my comment about supply was addressed. You never
responded, nothing explained in the changelog, nothing explained in the
commit msg.

> +required:
> +  - compatible
> +  - reg
> +  - spi-max-frequency
> +
> +allOf:
> +  - $ref: /schemas/spi/spi-peripheral-props.yaml#
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    // Example: ST7920 connected to an SPI bus

Drop comment.

> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    spi {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        display@0 {
> +            compatible = "sitronix,st7920";
> +            reg = <0>;
> +            spi-max-frequency = <600000>;
> +            spi-cs-high;
> +        };
> +    };
> 
> -- 
> 2.51.0
>

Re: [PATCH v2 2/3] dt-bindings: display: sitronix,st7920: Add DT schema

Posted by Iker Pedrosa 4 months, 4 weeks ago

El mié, 10 sept 2025 a las 13:35, Krzysztof Kozlowski
(<krzk@kernel.org>) escribió:
>
> On Tue, Sep 09, 2025 at 06:52:44PM +0200, Iker Pedrosa wrote:
> > Add binding for Sitronix ST7920 display.
> >
> > Signed-off-by: Iker Pedrosa <ikerpedrosam@gmail.com>
> > ---
> >  .../bindings/display/sitronix,st7920.yaml          | 52 ++++++++++++++++++++++
> >  1 file changed, 52 insertions(+)
> >
>
> Please organize the patch documenting compatible (DT bindings) before their user.
> See also: https://elixir.bootlin.com/linux/v6.14-rc6/source/Documentation/devicetree/bindings/submitting-patches.rst#L46
>
> ...
>
> > +  reg:
> > +    description: The chip-select number for the device on the SPI bus.
>
> Drop description, obvious/redundant.
>
> > +    maxItems: 1
> > +
> > +  spi-max-frequency:
> > +    maximum: 600000
> > +
>
> I don't see how my comment about supply was addressed. You never
> responded, nothing explained in the changelog, nothing explained in the
> commit msg.

Sorry, I forgot to answer.

No supplies are needed. There's an optional contrast for the display,
but this isn't strictly needed.

>
> > +required:
> > +  - compatible
> > +  - reg
> > +  - spi-max-frequency
> > +
> > +allOf:
> > +  - $ref: /schemas/spi/spi-peripheral-props.yaml#
> > +
> > +unevaluatedProperties: false
> > +
> > +examples:
> > +  - |
> > +    // Example: ST7920 connected to an SPI bus
>
> Drop comment.
>
> > +    #include <dt-bindings/gpio/gpio.h>
> > +
> > +    spi {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +
> > +        display@0 {
> > +            compatible = "sitronix,st7920";
> > +            reg = <0>;
> > +            spi-max-frequency = <600000>;
> > +            spi-cs-high;
> > +        };
> > +    };
> >
> > --
> > 2.51.0
> >