Re: [RFC PATCH 1/6] dt-bindings: display: imx: Add EPDC

Krzysztof Kozlowski
2022-02-17T09:21:23Z

On 06/02/2022 09:00, Andreas Kemnade wrote:
> Add a binding for the Electrophoretic Display Controller found at least
> in the i.MX6.
> The timing subnode is directly here to avoid having display parameters
> spread all over the plate.
>
> Supplies are organized the same way as in the fbdev driver in the
> NXP/Freescale kernel forks. The regulators used for that purpose,
> like the TPS65185, the SY7636A and MAX17135 have typically a single bit to
> start a bunch of regulators of higher or negative voltage with a
> well-defined timing. VCOM can be handled separately, but can also be
> incorporated into that single bit.
>
> Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
> ---
> .../bindings/display/imx/fsl,mxc-epdc.yaml | 159 ++++++++++++++++++
> 1 file changed, 159 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,mxc-epdc.yaml
>
> diff --git a/Documentation/devicetree/bindings/display/imx/fsl,mxc-epdc.yaml b/Documentation/devicetree/bindings/display/imx/fsl,mxc-epdc.yaml
> new file mode 100644
> index 000000000000..7e0795cc3f70
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/imx/fsl,mxc-epdc.yaml
> @@ -0,0 +1,159 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/display/imx/fsl,mxc-epdc.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Freescale i.MX6 EPDC
> +
> +maintainers:
> + - Andreas Kemnade <andreas@kemnade.info>
> +
> +description: |
> + The EPDC is a controller for handling electronic paper displays found in
> + i.MX6 SoCs.
> +
> +properties:
> + compatible:
> + enum:
> + - fsl,imx6sl-epdc
> + - fsl,imx6sll-epdc
> +
> + reg:
> + maxItems: 1
> +
> + clocks:
> + items:
> + - description: Bus clock
> + - description: Pixel clock
> +
> + clock-names:
> + items:
> + - const: axi
> + - const: pix
> +
> + interrupts:
> + maxItems: 1
> +
> + vscan-holdoff:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + maxItems: 1

Except what Rob already said, all these are not arrays, so maxItems is
not appropriate. You can define minimum/maximum values instead.

> +
> + sdoed-width:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + maxItems: 1
> +
> + sdoed-delay:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + maxItems: 1
> +
> + sdoez-width:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + maxItems: 1
> +
> + sdoez-delay:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + maxItems: 1
> +
> + gdclk-hp-offs:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + maxItems: 1
> +
> + gdsp-offs:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + maxItems: 1
> +
> + gdoe-offs:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + maxItems: 1
> +
> + gdclk-offs:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + maxItems: 1
> +
> + num-ce:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + maxItems: 1
> +
> + timing:
> + $ref: /display/panel/panel-timing.yaml#
> +
> + DISPLAY-supply:
> + description:
> + A couple of +/- voltages automatically powered on in a defintive order

Typo, definitive?

> +
> + VCOM-supply:
> + description: compensation voltage
> +
> + V3P3-supply:

All of supplies names - lowercase.

> + description: V3P3 supply
> +
> + epd-thermal-zone:
> + description:
> + Zone to get temperature of the EPD from, practically ambient temperature.

Is it a phandle?

> +
> +
> +
> +required:
> + - compatible
> + - reg
> + - clocks
> + - clock-names
> + - interrupts
> + - vscan-holdoff
> + - sdoed-width
> + - sdoed-delay
> + - sdoez-width
> + - sdoez-delay
> + - gdclk-hp-offs
> + - gdsp-offs
> + - gdoe-offs
> + - gdclk-offs
> + - num-ce
> +
> +additionalProperties: false
> +
> +examples:
> + - |
> + #include <dt-bindings/clock/imx6sl-clock.h>
> + #include <dt-bindings/interrupt-controller/arm-gic.h>
> +
> + epdc: epdc@20f4000 {

Generic node name, e.g. display-controller

> + compatible = "fsl,imx6sl-epdc";
> + reg = <0x020f4000 0x4000>;
> + interrupts = <0 97 IRQ_TYPE_LEVEL_HIGH>;

s/0/GIC_SPI/

> + clocks = <&clks IMX6SL_CLK_EPDC_AXI>, <&clks IMX6SL_CLK_EPDC_PIX>;
> + clock-names = "axi", "pix";
> +

Best regards,
Krzysztof