Re: [PATCH 11/14] dt-bindings: display: bridge: Add i.MX8qm/qxp LVDS display bridge binding

[Liu Ying <victor.liu@nxp.com>]

On Mon, 2020-12-21 at 15:33 -0700, Rob Herring wrote:
> On Thu, Dec 17, 2020 at 05:59:30PM +0800, Liu Ying wrote:
> > This patch adds bindings for i.MX8qm/qxp LVDS display bridge(LDB).
> > 
> > Signed-off-by: Liu Ying <victor.liu@nxp.com>
> > ---
> >  .../bindings/display/bridge/fsl,imx8qxp-ldb.yaml   | 185 +++++++++++++++++++++
> >  1 file changed, 185 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/display/bridge/fsl,imx8qxp-ldb.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/display/bridge/fsl,imx8qxp-ldb.yaml b/Documentation/devicetree/bindings/display/bridge/fsl,imx8qxp-ldb.yaml
> > new file mode 100644
> > index 00000000..4e5ff6f
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/display/bridge/fsl,imx8qxp-ldb.yaml
> > @@ -0,0 +1,185 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevicetree.org%2Fschemas%2Fdisplay%2Fbridge%2Ffsl%2Cimx8qxp-ldb.yaml%23&amp;data=04%7C01%7Cvictor.liu%40nxp.com%7C8d8e65cd4f0e45494d6408d8a60076d4%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637441868260775770%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=tvsqI6VbnO9Qe4CBJAcoHHK8uzszYWmy5hBSGaeqPmc%3D&amp;reserved=0
> > +$schema: https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevicetree.org%2Fmeta-schemas%2Fcore.yaml%23&amp;data=04%7C01%7Cvictor.liu%40nxp.com%7C8d8e65cd4f0e45494d6408d8a60076d4%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637441868260775770%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=%2FTDhBQJLEFxWH2Nm0zTodKEhajtCRoVJilT9jBtbUfA%3D&amp;reserved=0
> > +
> > +title: Freescale i.MX8qm/qxp LVDS Display Bridge
> > +
> > +maintainers:
> > +  - Liu Ying <victor.liu@nxp.com>
> > +
> > +description: |
> > +  The Freescale i.MX8qm/qxp LVDS Display Bridge(LDB) has two channels.
> > +
> > +  For i.MX8qxp LDB, each channel supports up to 24bpp parallel input color
> > +  format and can map the input to VESA or JEIDA standards.  The two channels
> > +  cannot be used simultaneously, that is to say, the user should pick one of
> > +  them to use.  Two LDB channels from two LDB instances can work together in
> > +  LDB split mode to support a dual link LVDS display.  The channel indexes
> > +  have to be different.  Channel0 outputs odd pixels and channel1 outputs
> > +  even pixels.
> > +
> > +  For i.MX8qm LDB, each channel additionally supports up to 30bpp parallel
> > +  input color format.  The two channels can be used simultaneously, either
> > +  in dual mode or split mode.  In dual mode, the two channels output identical
> > +  data.  In split mode, channel0 outputs odd pixels and channel1 outputs even
> > +  pixels.
> 
> This LDB doesn't share anything with prior ones?

i.MX53/6qdl/6sx/8mp/8qm/8qxp SoCs embed LDB.
Bridge drivers for them should be able to use the 'imx-ldb-helper'
added by patch 10/14, so they do share those logics.

i.MX53/6qdl LDB encoder driver is at drivers/gpu/drm/imx/imx-ldb.c.
It's essentially a drm encoder driver.  Efforts are needed to convert
it to be a pure drm bridge driver, just like the patch 12/14 and 13/14
for i.MX8qm/qxp LDB which live in drivers/gpu/drm/bridge. 'imx-drm' is
also needed to create drm encoders and connectors. So, a fair amount of
work. With that done, the
binding Documentation/devicetree/bindings/display/imx/ldb.txt for
i.MX53/6dql LDBs can be dropped and we can probably cover them by this
binding, though I see quite a few new/inconsitent propeties.

i.MX6sx and i.MX8mp LDBs have no drivers yet. They can be potentially
covered by this binding.

Liu Ying

> 
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - fsl,imx8qm-ldb
> > +      - fsl,imx8qxp-ldb
> > +
> > +  "#address-cells":
> > +    const: 1
> > +
> > +  "#size-cells":
> > +    const: 0
> > +
> > +  clocks:
> > +    items:
> > +      - description: pixel clock
> > +      - description: bypass clock
> > +
> > +  clock-names:
> > +    items:
> > +      - const: pixel
> > +      - const: bypass
> > +
> > +  power-domains:
> > +    maxItems: 1
> > +
> > +  fsl,syscon:
> > +    $ref: /schemas/types.yaml#/definitions/phandle
> > +    description: |
> > +      A phandle which points to Control and Status Registers(CSR) module.
> > +
> > +  fsl,companion-ldb:
> > +    $ref: /schemas/types.yaml#/definitions/phandle
> > +    description: |
> > +      A phandle which points to companion LDB which is used in LDB split mode.
> > +
> > +patternProperties:
> > +  "^channel@[0-1]$":
> > +    type: object
> > +    description: Represents a channel of LDB.
> > +
> > +    properties:
> > +      "#address-cells":
> > +        const: 1
> > +
> > +      "#size-cells":
> > +        const: 0
> > +
> > +      reg:
> > +        description: The channel index.
> > +        enum: [ 0, 1 ]
> > +
> > +      phys:
> > +        description: A phandle to the phy module representing the LVDS PHY.
> > +        maxItems: 1
> > +
> > +      phy-names:
> > +        const: lvds_phy
> > +
> > +      port@0:
> > +        type: object
> > +        description: Input port of the channel.
> > +
> > +        properties:
> > +          reg:
> > +            const: 0
> > +
> > +        required:
> > +          - reg
> > +
> > +      port@1:
> > +        type: object
> > +        description: Output port of the channel.
> > +
> > +        properties:
> > +          reg:
> > +            const: 1
> > +
> > +        required:
> > +          - reg
> > +
> > +    required:
> > +      - "#address-cells"
> > +      - "#size-cells"
> > +      - reg
> > +      - phys
> > +      - phy-names
> > +
> > +    additionalProperties: false
> > +
> > +required:
> > +  - compatible
> > +  - "#address-cells"
> > +  - "#size-cells"
> > +  - clocks
> > +  - clock-names
> > +  - power-domains
> > +  - fsl,syscon
> > +  - channel@0
> > +  - channel@1
> > +
> > +allOf:
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          contains:
> > +            const: fsl,imx8qm-ldb
> > +    then:
> > +      properties:
> > +        fsl,companion-ldb: false
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/firmware/imx/rsrc.h>
> > +    ldb {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +        compatible = "fsl,imx8qxp-ldb";
> > +        clocks = <&clk IMX_SC_R_LVDS_0 IMX_SC_PM_CLK_MISC2>,
> > +                 <&clk IMX_SC_R_LVDS_0 IMX_SC_PM_CLK_BYPASS>;
> > +        clock-names = "pixel", "bypass";
> > +        power-domains = <&pd IMX_SC_R_LVDS_0>;
> > +        fsl,syscon = <&mipi_lvds_0_csr>;
> > +
> > +        channel@0 {
> > +            #address-cells = <1>;
> > +            #size-cells = <0>;
> > +            reg = <0>;
> > +            phys = <&mipi_lvds_0_phy>;
> > +            phy-names = "lvds_phy";
> > +
> > +            port@0 {
> > +                reg = <0>;
> > +
> > +                mipi_lvds_0_ldb_ch0_mipi_lvds_0_pxl2dpi: endpoint {
> > +                    remote-endpoint = <&mipi_lvds_0_pxl2dpi_mipi_lvds_0_ldb_ch0>;
> > +                };
> > +            };
> > +        };
> > +
> > +        channel@1 {
> > +            #address-cells = <1>;
> > +            #size-cells = <0>;
> > +            reg = <1>;
> > +            phys = <&mipi_lvds_0_phy>;
> > +            phy-names = "lvds_phy";
> > +
> > +            port@0 {
> > +                reg = <0>;
> > +
> > +                mipi_lvds_0_ldb_ch1_mipi_lvds_0_pxl2dpi: endpoint {
> > +                    remote-endpoint = <&mipi_lvds_0_pxl2dpi_mipi_lvds_0_ldb_ch1>;
> > +                };
> > +            };
> > +        };
> > +    };
> > -- 
> > 2.7.4
> >