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Date:   Wed, 19 Aug 2020 19:40:16 +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 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.

> > > > +
> > > > +  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