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Date:   Fri, 11 Feb 2022 09:46:27 -0600
From:   Rob Herring <robh@kernel.org>
To:     Andreas Kemnade <andreas@kemnade.info>
Cc:     p.zabel@pengutronix.de, airlied@linux.ie, daniel@ffwll.ch,
        shawnguo@kernel.org, s.hauer@pengutronix.de, kernel@pengutronix.de,
        festevam@gmail.com, linux-imx@nxp.com,
        maarten.lankhorst@linux.intel.com, mripard@kernel.org,
        tzimmermann@suse.de, dri-devel@lists.freedesktop.org,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, alistair@alistair23.me,
        samuel@sholland.org, josua.mayer@jm0.eu,
        letux-kernel@openphoenux.org
Subject: Re: [RFC PATCH 1/6] dt-bindings: display: imx: Add EPDC
Message-ID: <YgaE06Ktabpf2dJC@robh.at.kernel.org>
References: <20220206080016.796556-1-andreas@kemnade.info>
 <20220206080016.796556-2-andreas@kemnade.info>
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On Sun, Feb 06, 2022 at 09:00:11AM +0100, Andreas Kemnade wrote:
> Add a binding for the Electrophoretic Display Controller found at least
> in the i.MX6.

The first version was in i.MX50 (I helped design the register 
interface). Is that version compatible?

> 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

Not compatible with each other?

> +
> +  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
> +
> +  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

All these need a vendor prefix and descriptions.

> +
> +  timing:
> +    $ref: /display/panel/panel-timing.yaml#
> +
> +  DISPLAY-supply:
> +    description:
> +      A couple of +/- voltages automatically powered on in a defintive order
> +
> +  VCOM-supply:
> +    description: compensation voltage
> +
> +  V3P3-supply:
> +    description: V3P3 supply
> +
> +  epd-thermal-zone:
> +    description:
> +      Zone to get temperature of the EPD from, practically ambient temperature.
> +
> +
> +

1 blank line.

> +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 {
> +        compatible = "fsl,imx6sl-epdc";
> +        reg = <0x020f4000 0x4000>;
> +        interrupts = <0 97 IRQ_TYPE_LEVEL_HIGH>;
> +        clocks = <&clks IMX6SL_CLK_EPDC_AXI>, <&clks IMX6SL_CLK_EPDC_PIX>;
> +        clock-names = "axi", "pix";
> +
> +        pinctrl-names = "default";
> +        pinctrl-0 = <&pinctrl_epdc0>;
> +        V3P3-supply = <&V3P3_reg>;
> +        VCOM-supply = <&VCOM_reg>;
> +        DISPLAY-supply = <&DISPLAY_reg>;
> +        epd-thermal-zone = "epd-thermal";
> +
> +        vscan-holdoff = <4>;
> +        sdoed-width = <10>;
> +        sdoed-delay = <20>;
> +        sdoez-width = <10>;
> +        sdoez-delay = <20>;
> +        gdclk-hp-offs = <562>;
> +        gdsp-offs = <662>;
> +        gdoe-offs = <0>;
> +        gdclk-offs = <225>;
> +        num-ce = <3>;
> +        status = "okay";

Don't need status in examples.

> +
> +        timing {
> +                clock-frequency = <80000000>;
> +                hactive = <1448>;
> +                hback-porch = <16>;
> +                hfront-porch = <102>;
> +                hsync-len = <28>;
> +                vactive = <1072>;
> +                vback-porch = <4>;
> +                vfront-porch = <4>;
> +                vsync-len = <2>;
> +        };
> +    };
> +...
> -- 
> 2.30.2
> 
>