Re: [PATCH v3 2/3] media: dt-bindings: media: xilinx: Add Xilinx UHD-SDI Receiver Subsystem

From: Laurent Pinchart
Date: Wed Aug 19 2020 - 12:40:45 EST

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@xxxxxxxxxx>
> > > > ---
> > > > 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@xxxxxxxxxx>
> > > > +
> > > > +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@xxxxxxxxxx>
> > > > + */
> > > > +
> > > > +#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