Re: [PATCH v7 5/8] dt-bindings: display: add i.MX6 MIPI DSI host controller doc

From: Adrian Ratiu <adrian.ratiu@collabora•com>
To: Laurent Pinchart <laurent.pinchart@ideasonboard•com>,
	Adrian Ratiu <adrian.ratiu@collabora•com>
Cc: Rob Herring <robh@kernel•org>,
	devicetree@vger•kernel.org,
	Jernej Skrabec <jernej.skrabec@siol•net>,
	Sjoerd Simons <sjoerd.simons@collabora•com>,
	Heiko Stuebner <heiko@sntech•de>,
	Adrian Pop <pop.adrian61@gmail•com>,
	Jonas Karlman <jonas@kwiboo•se>,
	Martyn Welch <martyn.welch@collabora•com>,
	Neil Armstrong <narmstrong@baylibre•com>,
	linux-kernel@vger•kernel.org, dri-devel@lists•freedesktop.org,
	Andrzej Hajda <a.hajda@samsung•com>,
	linux-rockchip@lists•infradead.org, linux-imx@nxp•com,
	Arnaud Ferraris <arnaud.ferraris@collabora•com>,
	kernel@collabora•com, Fabio Estevam <festevam@gmail•com>,
	linux-stm32@st-md-mailman•stormreply.com,
	linux-arm-kernel@lists•infradead.org
Subject: Re: [PATCH v7 5/8] dt-bindings: display: add i.MX6 MIPI DSI host controller doc
Date: Wed, 22 Apr 2020 19:19:50 +0300	[thread overview]
Message-ID: <87368vjxw9.fsf@collabora.com> (raw)
In-Reply-To: <20200422152956.GE28105@pendragon.ideasonboard.com>

On Wed, 22 Apr 2020, Laurent Pinchart 
<laurent.pinchart@ideasonboard•com> wrote:
> 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. 
>

Yes that is correct, there is just a single set of conf registers 
specified via reg.

>> 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

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