Re: [PATCH v11 1/2] dt-bindings: display/bridge: Add binding for NWL mipi dsi host controller

From: Guido Günther
Date: Fri Apr 10 2020 - 08:45:25 EST

Hi Laurent,
On Fri, Apr 10, 2020 at 02:23:42PM +0300, Laurent Pinchart wrote:
> Hi Guido,
>
> Thank you for the patch.
>
> On Thu, Apr 09, 2020 at 12:42:01PM +0200, Guido Günther wrote:
> > The Northwest Logic MIPI DSI IP core can be found in NXPs i.MX8 SoCs.
> >
> > Signed-off-by: Guido Günther <agx@xxxxxxxxxxx>
> > Tested-by: Robert Chiras <robert.chiras@xxxxxxx>
> > Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
> > Acked-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
> > Reviewed-by: Fabio Estevam <festevam@xxxxxxxxx>
> > ---
> > .../bindings/display/bridge/nwl-dsi.yaml | 226 ++++++++++++++++++
> > 1 file changed, 226 insertions(+)
> > create mode 100644 Documentation/devicetree/bindings/display/bridge/nwl-dsi.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/display/bridge/nwl-dsi.yaml b/Documentation/devicetree/bindings/display/bridge/nwl-dsi.yaml
> > new file mode 100644
> > index 000000000000..8aff2d68fc33
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/display/bridge/nwl-dsi.yaml
> > @@ -0,0 +1,226 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/display/bridge/nwl-dsi.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Northwest Logic MIPI-DSI controller on i.MX SoCs
> > +
> > +maintainers:
> > + - Guido Gúnther <agx@xxxxxxxxxxx>
> > + - Robert Chiras <robert.chiras@xxxxxxx>
> > +
> > +description: |
> > + NWL MIPI-DSI host controller found on i.MX8 platforms. This is a dsi bridge for
> > + the SOCs NWL MIPI-DSI host controller.
> > +
> > +properties:
> > + compatible:
> > + const: fsl,imx8mq-nwl-dsi
> > +
> > + reg:
> > + maxItems: 1
> > +
> > + interrupts:
> > + maxItems: 1
> > +
> > + '#address-cells':
> > + const: 1
> > +
> > + '#size-cells':
> > + const: 0
> > +
> > + clocks:
> > + items:
> > + - description: DSI core clock
> > + - description: RX_ESC clock (used in escape mode)
> > + - description: TX_ESC clock (used in escape mode)
> > + - description: PHY_REF clock
> > + - description: LCDIF clock
> > +
> > + clock-names:
> > + items:
> > + - const: core
> > + - const: rx_esc
> > + - const: tx_esc
> > + - const: phy_ref
> > + - const: lcdif
> > +
> > + mux-controls:
> > + description:
> > + mux controller node to use for operating the input mux
> > +
> > + phys:
> > + maxItems: 1
> > + description:
> > + A phandle to the phy module representing the DPHY
> > +
> > + phy-names:
> > + items:
> > + - const: dphy
> > +
> > + power-domains:
> > + maxItems: 1
> > +
> > + resets:
> > + items:
> > + - description: dsi byte reset line
> > + - description: dsi dpi reset line
> > + - description: dsi esc reset line
> > + - description: dsi pclk reset line
> > +
> > + reset-names:
> > + items:
> > + - const: byte
> > + - const: dpi
> > + - const: esc
> > + - const: pclk
> > +
> > + ports:
> > + type: object
> > + description:
> > + A node containing DSI input & output port nodes with endpoint
> > + definitions as documented in
> > + Documentation/devicetree/bindings/graph.txt.
> > + properties:
> > + port@0:
> > + type: object
> > + description:
> > + Input port node to receive pixel data from the
> > + display controller. Exactly one endpoint must be
> > + specified.
> > + properties:
> > + '#address-cells':
> > + const: 1
> > +
> > + '#size-cells':
> > + const: 0
> > +
> > + endpoint@0:
> > + description: sub-node describing the input from LCDIF
> > + type: object
> > +
> > + endpoint@1:
> > + description: sub-node describing the input from DCSS
> > + type: object
>
> This models the two inputs to the IP core, that are connected to a mux
> internally, controlled through mux-controls, right ? Why is a single
> endpoint supported then, if there are two connections at the hardware
> level, and why is this using endpoints instead of ports as there are
> really two input ports ?

That came out of

https://lore.kernel.org/linux-arm-kernel/c86b7ca2-7799-eafd-c380-e4b551520837@xxxxxxxxxxx/

# If the ip has separate lines for DCSS and LCDIF you should distinguish
# by port number. If they are shared
# you can use endpoint number to specify DCSS or LCDIF, in both cases
# bindings should be adjusted.

I read that as

- distinguish by endpoint number:

eLCDIF--\ |
----| nwl
DCSS----/ |

- distinguish by port number:

eLCDIF-------|
| nwl
DCSS --------|

>From the imx8mq ref manual i didn't see separate input lines for DCSS vs
eLCDIF the the NWL IP so i went with endpoints instead of ports. I'm
happy to change that if i got it wrong.

Cheers,
-- Guido

>
> Apart from that the bindings look ok to me.
>
> > +
> > + reg:
> > + const: 0
> > +
> > + required:
> > + - '#address-cells'
> > + - '#size-cells'
> > + - reg
> > +
> > + oneOf:
> > + - required:
> > + - endpoint@0
> > + - required:
> > + - endpoint@1
> > +
> > + additionalProperties: false
> > +
> > + port@1:
> > + type: object
> > + description:
> > + DSI output port node to the panel or the next bridge
> > + in the chain
> > +
> > + '#address-cells':
> > + const: 1
> > +
> > + '#size-cells':
> > + const: 0
> > +
> > + required:
> > + - '#address-cells'
> > + - '#size-cells'
> > + - port@0
> > + - port@1
> > +
> > + additionalProperties: false
> > +
> > +patternProperties:
> > + "^panel@[0-9]+$":
> > + type: object
> > +
> > +required:
> > + - '#address-cells'
> > + - '#size-cells'
> > + - clock-names
> > + - clocks
> > + - compatible
> > + - interrupts
> > + - mux-controls
> > + - phy-names
> > + - phys
> > + - ports
> > + - reg
> > + - reset-names
> > + - resets
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > + - |
> > +
> > + #include <dt-bindings/clock/imx8mq-clock.h>
> > + #include <dt-bindings/interrupt-controller/arm-gic.h>
> > + #include <dt-bindings/reset/imx8mq-reset.h>
> > +
> > + mipi_dsi: mipi_dsi@30a00000 {
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > + compatible = "fsl,imx8mq-nwl-dsi";
> > + reg = <0x30A00000 0x300>;
> > + clocks = <&clk IMX8MQ_CLK_DSI_CORE>,
> > + <&clk IMX8MQ_CLK_DSI_AHB>,
> > + <&clk IMX8MQ_CLK_DSI_IPG_DIV>,
> > + <&clk IMX8MQ_CLK_DSI_PHY_REF>,
> > + <&clk IMX8MQ_CLK_LCDIF_PIXEL>;
> > + clock-names = "core", "rx_esc", "tx_esc", "phy_ref", "lcdif";
> > + interrupts = <GIC_SPI 34 IRQ_TYPE_LEVEL_HIGH>;
> > + mux-controls = <&mux 0>;
> > + power-domains = <&pgc_mipi>;
> > + resets = <&src IMX8MQ_RESET_MIPI_DSI_RESET_BYTE_N>,
> > + <&src IMX8MQ_RESET_MIPI_DSI_DPI_RESET_N>,
> > + <&src IMX8MQ_RESET_MIPI_DSI_ESC_RESET_N>,
> > + <&src IMX8MQ_RESET_MIPI_DSI_PCLK_RESET_N>;
> > + reset-names = "byte", "dpi", "esc", "pclk";
> > + phys = <&dphy>;
> > + phy-names = "dphy";
> > +
> > + panel@0 {
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > + compatible = "rocktech,jh057n00900";
> > + reg = <0>;
> > + port@0 {
> > + reg = <0>;
> > + panel_in: endpoint {
> > + remote-endpoint = <&mipi_dsi_out>;
> > + };
> > + };
> > + };
> > +
> > + ports {
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > +
> > + port@0 {
> > + #size-cells = <0>;
> > + #address-cells = <1>;
> > + reg = <0>;
> > + mipi_dsi_in: endpoint@0 {
> > + reg = <0>;
> > + remote-endpoint = <&lcdif_mipi_dsi>;
> > + };
> > + };
> > + port@1 {
> > + reg = <1>;
> > + mipi_dsi_out: endpoint {
> > + remote-endpoint = <&panel_in>;
> > + };
> > + };
> > + };
> > + };
>
> --
> Regards,
>
> Laurent Pinchart
>