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

From: Liu Ying
Date: Mon Dec 21 2020 - 22:51:30 EST


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@xxxxxxx>
> > ---
> > .../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@xxxxxxx>
> > +
> > +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
> >