Re: [PATCH V8 09/12] dt-bindings: display: imx: add binding for i.MX8MP HDMI TX

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

On Fri, Feb 16, 2024 at 10:05:26AM +0100, Alexander Stein wrote:
> Hi all,
> 
> Am Samstag, 3. Februar 2024, 17:52:49 CET schrieb Adam Ford:
> > From: Lucas Stach <l.stach@pengutronix.de>
> > 
> > The HDMI TX controller on the i.MX8MP SoC is a Synopsys designware IP
> > core with a little bit of SoC integration around it.
> > 
> > Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> > Signed-off-by: Adam Ford <aford173@gmail.com>
> > 
> > ---
> > V3:  Change name and location to better idenfity as a bridge and
> >      HDMI 2.0a transmitter
> > 
> >      Fix typos and feedback from Rob and added ports.
> > ---
> >  .../display/bridge/fsl,imx8mp-hdmi-tx.yaml    | 102 ++++++++++++++++++
> >  1 file changed, 102 insertions(+)
> >  create mode 100644
> > Documentation/devicetree/bindings/display/bridge/fsl,imx8mp-hdmi-tx.yaml
> > 
> > diff --git
> > a/Documentation/devicetree/bindings/display/bridge/fsl,imx8mp-hdmi-tx.yaml
> > b/Documentation/devicetree/bindings/display/bridge/fsl,imx8mp-hdmi-tx.yaml
> > new file mode 100644
> > index 000000000000..3791c9f4ebab
> > --- /dev/null
> > +++
> > b/Documentation/devicetree/bindings/display/bridge/fsl,imx8mp-hdmi-tx.yaml
> > @@ -0,0 +1,102 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/display/bridge/fsl,imx8mp-hdmi-tx.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Freescale i.MX8MP DWC HDMI TX Encoder
> > +
> > +maintainers:
> > +  - Lucas Stach <l.stach@pengutronix.de>
> > +
> > +description:
> > +  The i.MX8MP HDMI transmitter is a Synopsys DesignWare
> > +  HDMI 2.0a TX controller IP.
> > +
> > +allOf:
> > +  - $ref: /schemas/display/bridge/synopsys,dw-hdmi.yaml#
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - fsl,imx8mp-hdmi-tx
> > +
> > +  reg-io-width:
> > +    const: 1
> > +
> > +  clocks:
> > +    maxItems: 4
> > +
> > +  clock-names:
> > +    items:
> > +      - const: iahb
> > +      - const: isfr
> > +      - const: cec
> > +      - const: pix
> > +
> > +  power-domains:
> > +    maxItems: 1
> > +
> > +  ports:
> > +    $ref: /schemas/graph.yaml#/properties/ports
> > +
> > +    properties:
> > +      port@0:
> > +        $ref: /schemas/graph.yaml#/properties/port
> > +        description: Parallel RGB input port
> > +
> > +      port@1:
> > +        $ref: /schemas/graph.yaml#/properties/port
> > +        description: HDMI output port
> > +
> > +    required:
> > +      - port@0
> > +      - port@1
> 
> Is this really correct that port@1 is required? AFAICS this host already 
> supports HPD and DDC by itself, so there is no need for a dedicated HDMI 
> connector.

The chip has an HDMI output, so there's an output port.

> With the current state of the drivers this output port is completely ignored 
> anyway. Yet it works for a lot of people.

DT bindings describe the hardware. From a DT point of view, tt's fine
for drivers to ignore the port (that may or may not be true from a DRM
point of view, but that's a separate discussion).

> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - clocks
> > +  - clock-names
> > +  - interrupts
> > +  - power-domains
> > +  - ports
> > +
> > +unevaluatedProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/clock/imx8mp-clock.h>
> > +    #include <dt-bindings/interrupt-controller/irq.h>
> > +    #include <dt-bindings/power/imx8mp-power.h>
> > +
> > +    hdmi@32fd8000 {
> > +        compatible = "fsl,imx8mp-hdmi-tx";
> > +        reg = <0x32fd8000 0x7eff>;
> > +        interrupts = <0 IRQ_TYPE_LEVEL_HIGH>;
> > +        clocks = <&clk IMX8MP_CLK_HDMI_APB>,
> > +                 <&clk IMX8MP_CLK_HDMI_REF_266M>,
> > +                 <&clk IMX8MP_CLK_32K>,
> > +                 <&hdmi_tx_phy>;
> > +        clock-names = "iahb", "isfr", "cec", "pix";
> > +        power-domains = <&hdmi_blk_ctrl IMX8MP_HDMIBLK_PD_HDMI_TX>;
> > +        reg-io-width = <1>;
> > +        ports {
> > +           #address-cells = <1>;
> > +           #size-cells = <0>;
> > +           port@0 {
> > +             reg = <0>;
> > +
> > +             hdmi_tx_from_pvi: endpoint {
> > +               remote-endpoint = <&pvi_to_hdmi_tx>;
> > +             };
> > +          };
> > +
> > +          port@1 {
> > +            reg = <1>;
> > +              hdmi_tx_out: endpoint {
> > +                remote-endpoint = <&hdmi0_con>;
> > +              };
> > +          };
> > +        };
> > +    };

-- 
Regards,

Laurent Pinchart