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Date:   Mon, 24 Aug 2020 04:00:22 +0300
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Vishal Sagar <vsagar@xilinx.com>
Cc:     Rob Herring <robh@kernel.org>, Hyun Kwon <hyunk@xilinx.com>,
        "hverkuil@xs4all.nl" <hverkuil@xs4all.nl>,
        "mchehab@kernel.org" <mchehab@kernel.org>,
        "mark.rutland@arm.com" <mark.rutland@arm.com>,
        Michal Simek <michals@xilinx.com>,
        "linux-media@vger.kernel.org" <linux-media@vger.kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "joe@perches.com" <joe@perches.com>,
        Sandip Kothari <sandipk@xilinx.com>,
        Dinesh Kumar <dineshk@xilinx.com>
Subject: Re: [PATCH v3 2/3] media: dt-bindings: media: xilinx: Add Xilinx
 UHD-SDI Receiver Subsystem
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Hi Vishal,

On Wed, Aug 19, 2020 at 07:40:16PM +0300, Laurent Pinchart wrote:
> On Wed, Aug 19, 2020 at 01:45:34PM +0000, Vishal Sagar wrote:
> > On Wednesday, July 15, 2020 9:59 PM, Laurent Pinchart wrote:
> >> On Mon, Jul 13, 2020 at 12:54:47PM -0600, Rob Herring wrote:
> >>> On Thu, Jun 18, 2020 at 11:03:03AM +0530, Vishal Sagar wrote:
> >>>> Add bindings documentation for Xilinx UHD-SDI Receiver Subsystem.
> >>>>
> >>>> The Xilinx UHD-SDI Receiver Subsystem consists of SMPTE UHD-SDI (RX) IP
> >>>> core, an SDI RX to Video Bridge IP core to convert SDI video to native
> >>>> video and a Video In to AXI4-Stream IP core to convert native video to
> >>>> AXI4-Stream.
> >>>>
> >>>> Signed-off-by: Vishal Sagar <vishal.sagar@xilinx.com>
> >>>> ---
> >>>> v3
> >>>> - bpc instead of bpp
> >>>> - removed bpc as required property (default to 10 bpc)
> >>>> - add dt-bindings/media/xilinx-sdi.h
> >>>> - made line-rate as u32 instead of string
> >>>> - fixed reg
> >>>> - fixed s/upto/up to/
> >>>>
> >>>> v2
> >>>> - Removed references to xlnx,video*
> >>>> - Fixed as per Sakari Ailus and Rob Herring's comments
> >>>> - Converted to yaml format
> >>>>
> >>>>  .../bindings/media/xilinx/xlnx,sdirxss.yaml   | 132 ++++++++++++++++++
> >>>>  include/dt-bindings/media/xilinx-sdi.h        |  20 +++
> >>>>  2 files changed, 152 insertions(+)
> >>>>  create mode 100644
> >> Documentation/devicetree/bindings/media/xilinx/xlnx,sdirxss.yaml
> >>>>  create mode 100644 include/dt-bindings/media/xilinx-sdi.h
> >>>>
> >>>> diff --git
> >> a/Documentation/devicetree/bindings/media/xilinx/xlnx,sdirxss.yaml
> >> b/Documentation/devicetree/bindings/media/xilinx/xlnx,sdirxss.yaml
> >>>> new file mode 100644
> >>>> index 000000000000..6cfc18ca435f
> >>>> --- /dev/null
> >>>> +++ b/Documentation/devicetree/bindings/media/xilinx/xlnx,sdirxss.yaml
> >>>> @@ -0,0 +1,132 @@
> >>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> >>>> +%YAML 1.2
> >>>> +---
> >>>> +$id: http://devicetree.org/schemas/media/xilinx/xlnx,sdirxss.yaml#
> >>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >>>> +
> >>>> +
> >> 
> >> I think a single blank line is enough.
> > 
> > Ok I will remove extra empty line in next version.
> > 
> >>>> +title: Xilinx SMPTE UHD-SDI Receiver Subsystem
> >>>> +
> >>>> +maintainers:
> >>>> +  - Vishal Sagar <vishal.sagar@xilinx.com>
> >>>> +
> >>>> +description: |
> >>>> +  The SMPTE UHD-SDI Receiver (RX) Subsystem allows you to quickly create systems
> >>>> +  based on SMPTE SDI protocols. It receives unaligned native SDI streams from
> >>>> +  the SDI GT PHY and outputs an AXI4-Stream video stream, native video, or
> >>>> +  native SDI using Xilinx transceivers as the physical layer.
> >>>> +
> >>>> +  The subsystem consists of
> >>>> +  1 - SMPTE UHD-SDI Rx
> >>>> +  2 - SDI Rx to Native Video Bridge
> >>>> +  3 - Video In to AXI4-Stream Bridge
> >>>> +
> >>>> +  The subsystem can capture SDI streams in up to 12G mode 8 data streams and output
> >>>> +  a dual pixel per clock RGB/YUV444,422/420 10/12 bits per component AXI4-Stream.
> >>>> +
> >>>> +properties:
> >>>> +  compatible:
> >>>> +    items:
> >>>> +      - enum:
> >>>> +        - xlnx,v-smpte-uhdsdi-rx-ss-2.0
> >>>
> >>> Should be indented 2 more spaces.
> >> 
> >> Or you could simply use
> >> 
> >> properties:
> >>   compatible:
> >>     const: xlnx,v-smpte-uhdsdi-rx-ss-2.0
> > 
> > Ok I will fix this in the next version.
> > 
> >>>> +
> >>>> +  reg:
> >>>> +    maxItems: 1
> >>>> +
> >>>> +  interrupts:
> >>>> +    maxItems: 1
> >>>> +
> >>>> +  clocks:
> >>>> +    description: List of clock specifiers
> >>>
> >>> Drop. That's every 'clocks' property.
> > 
> > Ok I will drop the description in next version.
> > 
> >>>> +    items:
> >>>> +      - description: AXI4-Lite clock
> >>>> +      - description: SMPTE UHD-SDI Rx core clock
> >>>> +      - description: Video clock
> >>>> +
> >>>> +  clock-names:
> >>>> +    items:
> >>>> +      - const: s_axi_aclk
> >>>> +      - const: sdi_rx_clk
> >>>> +      - const: video_out_clk
> >>>> +
> >>>> +  xlnx,bpc:
> >>>> +    description: Bits per component supported. Can be 10 or 12 bits per component only.
> >>>> +    allOf:
> >>>
> >>> You can drop the 'allOf' now.
> > 
> > Ok will update this in next version.
> > 
> >>>> +      - $ref: "/schemas/types.yaml#/definitions/uint32"
> >>>> +      - enum: [10, 12]
> >>>
> >>> Seems like this should be a standard property?
> >> 
> >> Rob, if my understanding is correct, this tells for how many bits per
> >> component the IP core has been synthesized. I think it qualifies as a
> >> vendor property, as how to express constraints on supported formats (for
> >> IP cores that can be synthesized with different options) is highly
> >> vendor-specific.
> > 
> > Right Laurent. This is specific to Xilinx Video IP cores.
> > 
> >> Vishal, I think the question I asked in the review of v2 fell through
> >> the cracks. Is the documentation for the new IP core version available ?
> >> Should this property only be allowed for the new version, given that in
> >> v2.0 the BPC is fixed to 10 ?
> > 
> > The new IP core is released with Vivado 2020.1 but the documentation isn't yet
> > publicly updated.
> > 
> > This property is optional and the driver defaults to 10bpc in case this property is not specified.
> 
> So how about the following ?
> 
> properties:
>   compatible:
>     enum:
>       - xlnx,v-smpte-uhdsdi-rx-ss-1.0
>       - xlnx,v-smpte-uhdsdi-rx-ss-2.0
> 
>   ...
> 
>   xlnx,bpc:
>     description: ...
>     $ref: "/schemas/types.yaml#/definitions/uint32"
>     enum: [10, 12]
>     default: 10
> 
>   ...
> 
> allOf:
>   - if:
>       not:
>         properties:
>           compatible:
>             contains:
>               xlnx,v-smpte-uhdsdi-rx-ss-2.0
>     then:
>       properties:
>         xlnx,bpc: false
> 
> This indicates that the xlnx,bpc property isn't allowed for v1.0.
> Another option would be
> 
>     then:
>       properties:
>         xlnx,bpc:
> 	  const: 10
> 
> to indicate it must be equal to 10 on v1.0.

Following our offline discussion, I've revisited this review. It turns
out I have confused IP core versions. The version that only supports 10
bpc is v2.0, while I assume that the version that will support both 10
and 12 bpc will be v3.

Would the following make sense ?

properties:
  compatible:
    enum:
      - xlnx,v-smpte-uhdsdi-rx-ss-2.0
      - xlnx,v-smpte-uhdsdi-rx-ss-3.0

  ...

  xlnx,bpc:
    description: ...
    $ref: "/schemas/types.yaml#/definitions/uint32"
    enum: [10, 12]
    default: 10

  ...

allOf:
  - if:
      not:
        properties:
          compatible:
            contains:
              xlnx,v-smpte-uhdsdi-rx-ss-3.0
    then:
      properties:
        xlnx,bpc: false

Or, as proposed above,

     then:
       properties:
         xlnx,bpc:
           const: 10

> >>>> +
> >>>> +  xlnx,line-rate:
> >>>> +    description: |
> >>>> +      The maximum mode supported by the design. Possible values are as below
> >>>> +      0 - XSDI_STD_3G      -  3G mode
> >>>> +      1 - XSDI_STD_6G      -  6G mode
> >>>> +      2 - XSDI_STD_12G_8DS - 12G mode with 8 data streams
> >>>> +    allOf:
> >>>> +      - $ref: "/schemas/types.yaml#/definitions/uint32"
> >>>> +      - enum: [0, 1, 2]
> >>>
> >>> Standard?
> >> 
> >> For this one, I'm not sure. There's little support for SDI in the
> >> kernel, and I'm sure we'll get this wrong the first time. I'd rather try
> >> not to over-standardize properties before we have more examples.
> > 
> > Right. These are specific to Xilinx SDI Rx IP configuration.
> 
> I'm not sure it's Xilinx-specific, but I think we don't have enough
> examples of other SDI receivers to know if the propery could be made
> generic or not.
> 
> >>>> +
> >>>> +  xlnx,include-edh:
> >>>> +    type: boolean
> >>>> +    description: |
> >>>> +      This is present when the Error Detection and Handling processor is
> >>>> +      enabled in design.
> >>>> +
> >>>> +  ports:
> >>>> +    type: object
> >>>> +    description: |
> >>>> +      Generally the SDI port is connected to a device like SDI Broadcast camera
> >>>> +      which is independently controlled. Hence port@0 is a source port which can be
> >>>> +      connected to downstream IP which can work with AXI4 Stream data.
> >>>> +    properties:
> >>>> +      port@0:
> >>>> +        type: object
> >>>> +        description: Source port
> >>>> +        properties:
> >>>> +          reg:
> >>>> +            const: 0
> >>>> +          endpoint:
> >>>> +            type: object
> >>>> +            properties:
> >>>> +              remote-endpoint: true
> >>>> +            required:
> >>>> +              - remote-endpoint
> >>>> +            additionalProperties: false
> >>>> +        additionalProperties: false
> >> 
> >> Same here, I explained in the review of v2 that we should have an input
> >> port.
> > 
> > I will add the input / sink port to this device tree node.
> > 
> >>>> +
> >>>> +required:
> >>>> +  - compatible
> >>>> +  - reg
> >>>> +  - interrupts
> >>>> +  - clocks
> >>>> +  - clock-names
> >>>> +  - xlnx,line-rate
> >>>> +  - ports
> >>>> +
> >>>> +additionalProperties: false
> >>>> +
> >>>> +examples:
> >>>> +  - |
> >>>> +    #include <dt-bindings/media/xilinx-sdi.h>
> >>>> +    uhdsdirxss: v-smpte-uhdsdi-rxss@80000000 {
> >> 
> >> The label is not used, you can drop it.
> > 
> > Ok. I will remove this in the next version.
> > 
> >>>> +      compatible = "xlnx,v-smpte-uhdsdi-rx-ss-2.0";
> >>>> +      interrupt-parent = <&gic>;
> >>>> +      interrupts = <0 89 4>;
> >>>> +      reg = <0x80000000 0x10000>;
> >>>> +      xlnx,include-edh;
> >>>> +      xlnx,line-rate = <XSDI_STD_12G_8DS>;
> >>>> +      clocks = <&clk_1>, <&si570_1>, <&clk_2>;
> >>>> +      clock-names = "s_axi_aclk", "sdi_rx_clk", "video_out_clk";
> >>>> +      xlnx,bpc = <10>;
> >> 
> >> I would group the xlnx,* properties after the standard properties.
> > 
> > Noted. Will update in next version.
> > 
> >>>> +
> >>>> +      ports {
> >>>> +        #address-cells = <1>;
> >>>> +        #size-cells = <0>;
> >>>> +        port@0 {
> >>>> +          reg = <0>;
> >>>> +          sdirx_out: endpoint {
> >>>> +            remote-endpoint = <&vcap_sdirx_in>;
> >>>> +          };
> >>>> +        };
> >>>> +      };
> >>>> +    };
> >>>> +...
> >>>> diff --git a/include/dt-bindings/media/xilinx-sdi.h b/include/dt-bindings/media/xilinx-sdi.h
> >>>> new file mode 100644
> >>>> index 000000000000..11938fade041
> >>>> --- /dev/null
> >>>> +++ b/include/dt-bindings/media/xilinx-sdi.h
> >>>> @@ -0,0 +1,20 @@
> >>>> +/* SPDX-License-Identifier: GPL-2.0 */
> >>>> +/*
> >>>> + * Xilinx SDI device tree bindings
> >>>> + *
> >>>> + * Copyright (C) 2020 Xilinx, Inc.
> >>>> + *
> >>>> + * Contacts: Vishal Sagar <vishal.sagar@xilinx.com>
> >>>> + */
> >>>> +
> >>>> +#ifndef __DT_BINDINGS_MEDIA_XILINX_SDI_H__
> >>>> +#define __DT_BINDINGS_MEDIA_XILINX_SDI_H__
> >>>> +
> >>>> +/*
> >>>> + * SDI Configurations
> >>>> + */
> >>>> +#define XSDI_STD_3G		0
> >>>> +#define XSDI_STD_6G		1
> >>>> +#define XSDI_STD_12G_8DS	2
> >>>> +
> >>>> +#endif /* __DT_BINDINGS_MEDIA_XILINX_SDI_H__ */

-- 
Regards,

Laurent Pinchart