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Date:   Wed, 22 Apr 2020 18:29:56 +0300
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Adrian Ratiu <adrian.ratiu@collabora.com>
Cc:     linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
        linux-rockchip@lists.infradead.org,
        Jernej Skrabec <jernej.skrabec@siol.net>,
        Heiko Stuebner <heiko@sntech.de>,
        Jonas Karlman <jonas@kwiboo.se>, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org,
        Andrzej Hajda <a.hajda@samsung.com>, kernel@collabora.com,
        linux-stm32@st-md-mailman.stormreply.com, linux-imx@nxp.com,
        Rob Herring <robh@kernel.org>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Fabio Estevam <festevam@gmail.com>,
        Adrian Pop <pop.adrian61@gmail.com>,
        Arnaud Ferraris <arnaud.ferraris@collabora.com>,
        Sjoerd Simons <sjoerd.simons@collabora.com>,
        Martyn Welch <martyn.welch@collabora.com>
Subject: Re: [PATCH v7 5/8] dt-bindings: display: add i.MX6 MIPI DSI host
 controller doc
Message-ID: <20200422152956.GE28105@pendragon.ideasonboard.com>
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Hi Adrian,

On Wed, Apr 22, 2020 at 01:15:41PM +0300, Adrian Ratiu wrote:
> On Wed, 22 Apr 2020, Laurent Pinchart wrote:
> > On Wed, Apr 22, 2020 at 03:58:33AM +0300, Laurent Pinchart wrote: 
> >> On Tue, Apr 21, 2020 at 07:16:07PM +0300, Adrian Ratiu wrote: 
> >>> This provides an example DT binding for the MIPI DSI host 
> >>> controller present on the i.MX6 SoC based on Synopsis 
> >>> DesignWare v1.01 IP.   Cc: Rob Herring <robh@kernel.org> Cc: 
> >>> Neil Armstrong <narmstrong@baylibre.com> Cc: Fabio Estevam 
> >>> <festevam@gmail.com> Cc: Laurent Pinchart 
> >>> <laurent.pinchart@ideasonboard.com> Cc: 
> >>> devicetree@vger.kernel.org Tested-by: Adrian Pop 
> >>> <pop.adrian61@gmail.com> Tested-by: Arnaud Ferraris 
> >>> <arnaud.ferraris@collabora.com> Signed-off-by: Sjoerd Simons 
> >>> <sjoerd.simons@collabora.com> Signed-off-by: Martyn Welch 
> >>> <martyn.welch@collabora.com> Signed-off-by: Adrian Ratiu 
> >>> <adrian.ratiu@collabora.com> --- Changes since v6: 
> >>>   - Added ref to the newly created snps,dw-mipi-dsi.yaml 
> >>>   (Laurent) - Moved *-cells properties outside 
> >>>   patternProperties (Laurent) - Removed the panel port 
> >>>   documentation (Laurent) - Wrapped lines at 80 chars, typo 
> >>>   fixes, sort includes (Laurent) 
> >>>  Changes since v5: 
> >>>   - Fixed missing reg warning (Fabio) - Updated dt-schema and 
> >>>   fixed warnings (Rob) 
> >>>  Changes since v4: 
> >>>   - Fixed yaml binding to pass `make dt_binding_check 
> >>>   dtbs_check` and addressed received binding feedback (Rob) 
> >>>  Changes since v3: 
> >>>   - Added commit message (Neil) - Converted to yaml format 
> >>>   (Neil) - Minor dt node + driver fixes (Rob) - Added small 
> >>>   panel example to the host controller binding 
> >>>  Changes since v2: 
> >>>   - Fixed commit tags (Emil) 
> >>> --- 
> >>>  .../display/imx/fsl,mipi-dsi-imx6.yaml        | 135 
> >>>  ++++++++++++++++++ 1 file changed, 135 insertions(+) create 
> >>>  mode 100644 
> >>>  Documentation/devicetree/bindings/display/imx/fsl,mipi-dsi-imx6.yaml 
> >>>  diff --git 
> >>> a/Documentation/devicetree/bindings/display/imx/fsl,mipi-dsi-imx6.yaml 
> >>> b/Documentation/devicetree/bindings/display/imx/fsl,mipi-dsi-imx6.yaml 
> >>> new file mode 100644 index 0000000000000..b73e3ae33a852 --- 
> >>> /dev/null +++ 
> >>> b/Documentation/devicetree/bindings/display/imx/fsl,mipi-dsi-imx6.yaml 
> >>> @@ -0,0 +1,135 @@ +# SPDX-License-Identifier: (GPL-2.0-only 
> >>> OR BSD-2-Clause) +%YAML 1.2 +--- +$id: 
> >>> http://devicetree.org/schemas/display/imx/fsl,mipi-dsi-imx6.yaml# 
> >>> +$schema: http://devicetree.org/meta-schemas/core.yaml# + 
> >>> +title: Freescale i.MX6 DW MIPI DSI Host Controller + 
> >>> +maintainers: +  - Adrian Ratiu <adrian.ratiu@collabora.com> 
> >>> + +description: | +  The i.MX6 DSI host controller is a 
> >>> Synopsys DesignWare MIPI DSI v1.01 +  IP block with a 
> >>> companion PHY IP. 
> > 
> > I forgot to mention, if there's a companion PHY, shouldn't it be 
> > referenced from the DT bindings ? 
> 
> I don't think so, that description was copied verbatim from the 
> imx6 ref manual IIRC, the physical layer is the same for MIPI DSI 
> which does TX as for MIPI CSI which does RX, but looking at the 
> ref manual and how drivers are written I don't think it's 
> necessary.

Does that mean that the PHY is controlled through the registers
specified by the reg property ? If so then this is fine.

> This might change if we wanted to unify the DSI and CSI drivers a 
> bit, but considering the scope already associated with this patch 
> series I'm a bit afraid to open a subject like that =)

That's understandable :-)

> >>> +
> >>> +  These DT bindings follow the Synopsys DW MIPI DSI bindings defined in
> >>> +  Documentation/devicetree/bindings/display/bridge/dw_mipi_dsi.txt with
> >>> +  the following device-specific properties.
> >>> +
> >>> +allOf:
> >>> +  - $ref: ../bridge/snps,dw-mipi-dsi.yaml#
> >>> +
> >>> +properties:
> >>> +  '#address-cells':
> >>> +    const: 1
> >>> +
> >>> +  '#size-cells':
> >>> +    const: 0
> >>> +
> >>> +  compatible:
> >>> +    items:
> >>> +      - const: fsl,imx6q-mipi-dsi
> >>> +      - const: snps,dw-mipi-dsi
> >>> +
> >>> +  reg:
> >>> +    maxItems: 1
> >>> +
> >>> +  interrupts:
> >>> +    maxItems: 1
> >>> +
> >>> +  clocks:
> >>> +    items:
> >>> +      - description: Module Clock
> >>> +      - description: DSI bus clock
> >>> +
> >>> +  clock-names:
> >>> +    items:
> >>> +      - const: ref
> >>> +      - const: pclk
> >>> +
> >>> +  fsl,gpr:
> >>> +    description:
> >>> +      Phandle to the iomuxc-gpr region containing the multiplexer ctrl register.
> >>> +    $ref: /schemas/types.yaml#/definitions/phandle
> >>> +
> >>> +  ports:
> >>> +    type: object
> >>> +    description: |
> >>> +      A node containing DSI input & output port nodes with endpoint
> >>> +      definitions as documented in
> >>> +      Documentation/devicetree/bindings/media/video-interfaces.txt
> >>> +      Documentation/devicetree/bindings/graph.txt
> >>> +    properties:
> >>> +      port@0:
> >>> +        type: object
> >>> +        description:
> >>> +          DSI input port node, connected to the ltdc rgb output port.
> >>> +
> >>> +      port@1:
> >>> +        type: object
> >>> +        description:
> >>> +          RGB output port node, connected to a panel or a bridge input port.
> >> 
> >> Isn't it the other way around, doesn't the bridge take RGB input and
> >> output DSI ? And to be precise, it's not about RGB, but about the input
> >> being parallel interface (DSI will also carry RGB).
> >> 
> >> I would add
> >> 
> >>     required:
> >>       - port@0
> >>       - port@1
> >> 
> >>> +
> >>> +additionalProperties: false
> >>> +
> >>> +patternProperties:
> >>> +  "^panel@[0-3]$":
> >>> +    type: object
> >>> +
> >>> +required:
> >>> +  - "#address-cells"
> >>> +  - "#size-cells"
> >>> +  - compatible
> >>> +  - reg
> >>> +  - interrupts
> >>> +  - clocks
> >>> +  - clock-names
> >>> +  - ports
> >>> +
> >>> +examples:
> >>> +  - |+
> >>> +    #include <dt-bindings/clock/imx6qdl-clock.h>
> >>> +    #include <dt-bindings/gpio/gpio.h>
> >>> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> >>> +
> >>> +    dsi: dsi@21e0000 {
> >>> +        #address-cells = <1>;
> >>> +        #size-cells = <0>;
> >>> +        compatible = "fsl,imx6q-mipi-dsi", "snps,dw-mipi-dsi";
> >>> +        reg = <0x021e0000 0x4000>;
> >>> +        interrupts = <0 102 IRQ_TYPE_LEVEL_HIGH>;
> >>> +        fsl,gpr = <&gpr>;
> >>> +        clocks = <&clks IMX6QDL_CLK_MIPI_CORE_CFG>,
> >>> +                 <&clks IMX6QDL_CLK_MIPI_IPG>;
> >>> +        clock-names = "ref", "pclk";
> >>> +
> >>> +        ports {
> >>> +            #address-cells = <1>;
> >>> +            #size-cells = <0>;
> >> 
> >> port@0 is missing.
> >> 
> >>> +            port@1 {
> >>> +                reg = <1>;
> >>> +                dsi_out: endpoint {
> >>> +                    remote-endpoint = <&panel_in>;
> >>> +                };
> >>> +            };
> >>> +        };
> >>> +
> >>> +        panel@0 {
> >>> +            compatible = "sharp,ls032b3sx01";
> >>> +            reg = <0>;
> >>> +            reset-gpios = <&gpio6 8 GPIO_ACTIVE_LOW>;
> >>> +            ports {
> >>> +                #address-cells = <1>;
> >>> +                #size-cells = <0>;
> >>> +                port@0 {
> >>> +                    reg = <0>;
> >>> +                    panel_in: endpoint {
> >>> +                        remote-endpoint = <&dsi_out>;
> >>> +                    };
> >>> +                };
> >>> +            };
> >>> +        };
> >>> +    };
> >>> +
> >>> +...

-- 
Regards,

Laurent Pinchart