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Date:   Wed, 2 Oct 2019 10:22:01 +0300
From:   Sakari Ailus <sakari.ailus@iki.fi>
To:     Vishal Sagar <vishal.sagar@xilinx.com>
Cc:     Hyun Kwon <hyun.kwon@xilinx.com>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Michal Simek <michal.simek@xilinx.com>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
        Dinesh Kumar <dineshk@xilinx.com>,
        Sandip Kothari <sandipk@xilinx.com>
Subject: Re: [PATCH 1/2] media: dt-bindings: media: xilinx: Add Xilinx
 UHD-SDI Receiver Subsystem
Message-ID: <20191002072201.GL896@valkosipuli.retiisi.org.uk>
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Hi Vishal,

On Tue, Jun 04, 2019 at 07:25:55PM +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>
> ---
>  .../bindings/media/xilinx/xlnx,sdirxss.txt         | 80 ++++++++++++++++++++++
>  1 file changed, 80 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/media/xilinx/xlnx,sdirxss.txt
> 
> diff --git a/Documentation/devicetree/bindings/media/xilinx/xlnx,sdirxss.txt b/Documentation/devicetree/bindings/media/xilinx/xlnx,sdirxss.txt
> new file mode 100644
> index 0000000..8445bee
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/xilinx/xlnx,sdirxss.txt
> @@ -0,0 +1,80 @@
> +
> +Xilinx SMPTE UHD-SDI Receiver Subsystem Device Tree Bindings
> +------------------------------------------------------------
> +
> +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 utpo 12G mode and output a dual pixel
> +per clock YUV 422 or 420 10 bits per component AXI4-Stream.
> +
> +Required properties:
> +--------------------
> +- compatible: Must contain "xlnx,v-smpte-uhdsdi-rx-ss"
> +- reg: Physical base address and length of the registers set for the device.
> +- interrupts: Contains the interrupt line number.
> +- clocks: List of phandles to AXI4-Lite clock, core clock to SMPTE UHD-SDI Rx
> +  and Video clocks.
> +- clock-names: Must contain "s_axi_aclk", "sdi_rx_clk" and "video_out_clk" in
> +  the same order as clocks listed in clocks property.
> +- xlnx,line-rate: The maximum mode supported by the design. Possible values are
> +  are as below -
> +  12G_SDI_8DS	- 12G mode
> +  6G_SDI	-  6G mode
> +  3G_SDI	-  3G mode

Is this specific to a port?

I was wondering whether we should include this to video-interfaces.txt bus
type list, and V4L2 MBUS types. This way it could be also parsed by the
v4l2-fwnode framework.

Looking at the Wikipedia article, there are preceding standards, too, that
are referred to by a pair of letters:

<URL:https://en.wikipedia.org/wiki/Serial_digital_interface#Standards>

What does "DS" stand for?

> +
> +Optional properties:
> +--------------------
> +- xlnx,include-edh: This is present when the Error Detection and Handling
> +  processor is enabled in design.
> +
> +Ports
> +-----
> +The device node shall contain one 'port' child node as defined in
> +Documentation/devicetree/bindings/media/video-interfaces.txt.
> +
> +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.
> +
> +Required port properties:
> +-------------------------
> +- reg: 0 - for source port.
> +
> +- xlnx,video-format: This can be XVIP_VF_YUV_422 or XVIP_VF_YUV_420.

Is this a property of the hardware?

> +- xlnx,video-width: This is should be 10.

This, too. If there's just one choice, is there a need for the property?

> +
> +Example:
> +		v_smpte_uhdsdi_rx_ss: v_smpte_uhdsdi_rx_ss@80000000 {
> +			compatible = "xlnx,v-smpte-uhdsdi-rx-ss";
> +			interrupt-parent = <&gic>;
> +			interrupts = <0 89 4>;
> +			reg = <0x0 0x80000000 0x0 0x10000>;
> +			xlnx,include-edh;
> +			xlnx,line-rate = "12G_SDI_8DS";
> +			clocks = <&clk_1>, <&si570_1>, <&clk_2>;
> +			clock-names = "s_axi_aclk", "sdi_rx_clk", "video_out_clk";
> +
> +			ports {
> +				#address-cells = <1>;
> +				#size-cells = <0>;
> +
> +				port@0 {
> +					reg = <0>;
> +
> +					xlnx,video-format = <XVIP_VF_YUV_422>;
> +					xlnx,video-width = <10>;
> +
> +					sdirx_out: endpoint {
> +						remote-endpoint = <&vcap_sdirx_in>;
> +					};
> +				};
> +			};
> +		};

-- 
Regards,

Sakari Ailus