Hello Eugen, On Thu, Nov 12, 2020 at 03:34:35PM +0200, Eugen Hristev wrote: > Add bindings documentation for Microchip CSI2 Demultiplexer controller. > > CSI2DC is a demultiplexer from Synopsys IDI interface specification to > parallel interface connection or direct memory access. > > Signed-off-by: Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx> > --- > Changes in v5: > - modified bindings as per Rob Herring review > > Changes in v4: > - Removed property for inter-line-delay and for clock continuous/non-continuous > - Removed virtual channel by reg for second endpoint > > Changes in v3: > - Removed some text from description, as it was explained in the schema > - fixed other things as per Rob's review > - moved some text inside the schema, like the clock description > > Changes in v2: > - fixed warnings reported by dt_binding_check > > .../bindings/media/microchip,csi2dc.yaml | 119 ++++++++++++++++++ > 1 file changed, 119 insertions(+) > create mode 100644 Documentation/devicetree/bindings/media/microchip,csi2dc.yaml > > diff --git a/Documentation/devicetree/bindings/media/microchip,csi2dc.yaml b/Documentation/devicetree/bindings/media/microchip,csi2dc.yaml > new file mode 100644 > index 000000000000..e79f0d6ba9db > --- /dev/null > +++ b/Documentation/devicetree/bindings/media/microchip,csi2dc.yaml > @@ -0,0 +1,119 @@ > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) > +%YAML 1.2 > +--- > +$id: http://devicetree.org/schemas/media/microchip,csi2dc.yaml# > +$schema: http://devicetree.org/meta-schemas/core.yaml# > + > +title: Microchip CSI2 Demux Controller (CSI2DC) > + > +maintainers: > + - Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx> > + > +description: > + CSI2DC - Camera Serial Interface 2 Demux Controller > + > + CSI2DC is a hardware block that receives incoming data from an IDI interface > + and filters packets based on their data type and virtual channel identifier, > + then converts the byte stream into a cross clock domain to a pixel stream > + to a parallel interface that can be read by a sensor controller. > + > + CSI2DC provides two pipes, one video pipe and one data pipe. Video pipe > + is connected to a sensor controller and the data pipe is accessible > + as a DMA slave port to a DMA controller. > + > + CSI2DC supports a single 'port' node as a source pad with Synopsys 32-bit > + IDI interface. The connected endpoint must be a IDI interface compatible > + device (like Synopsys CSI2HOST) , that can provide 32-bit IDI interface > + connection as sink pad. Comments on a description from a non-native speaker might be mis-leading, take the following as suggestions only :) the here mentioned port node is said to be a 'source' to which an IDI interface that provides data is connected ? Is this a s/sink/source mistake or did you mean the first port node has to be connected to a source (the IDI interface) ? Also, maybe it's me but 'pad' is a media-controller concept, which should not be mentioned in bindings (as well as 'source' and 'sink' but they have a more generic usage) The first port, to me, is simply an 'IDI input port' > + For media entity and endpoints please refer to the bindings defined in > + Documentation/devicetree/bindings/media/video-interfaces.txt. I would drop 'media-entity'. To be honest I would drop this phrase and mention ../video-interfaces.txt in the ports description. Up to you. > + For Synopsys IDI interface please refer to > + Documentation/devicetree/bindings/media/snps,dw-csi-plat.txt > + > + CSI2DC supports one 'port' node as sink pad with parallel interface. This is > + called video pipe. I'm confused again, isn't the parallel interface an output ? Why is it said to be a 'sink pad' ? Isn't port one simply a 'video output port' ? Also the association between bindings' 'port' and their representation as media-controller constructs should in my opinion be avoided. Bindings are about describing hardware, and they could be used by non-Linux systems as well (at least, I've been told this multiple times :) > + This port has an 'endpoint' can then be used as a source pad for another > + controller (next in pipeline). > + Please refer to the bindings defined in > + Documentation/devicetree/bindings/media/video-interfaces.txt. > + > + CSI2DC also supports direct access to the data through AHB, via DMA channel, > + called data pipe. Is my understanding correct of this 'direct access' is not represented in DTS ? > + Because of this, the sink 'port' child node (second) is not mandatory. > + If the sink 'port' child node is missing, only data pipe is available. And so the DMA channel and the output video port are mutually exclusive ? I feel like the DMA port should be described or at least represented and made exclusive with port1 presence ? > + > +properties: > + compatible: > + const: microchip,sama7g5-csi2dc > + > + reg: > + maxItems: 1 > + > + clocks: > + maxItems: 2 > + > + clock-names: > + description: > + CSI2DC must have two clocks to function correctly. One clock is the > + peripheral clock for the inside functionality of the hardware block. > + This is named 'pclk'. The second clock must be the cross domain clock, > + in which CSI2DC will perform clock crossing. This clock must be fed > + by the next controller in pipeline, which usually is a sensor controller. > + Normally this clock should be given by this sensor controller who > + is also a clock source. This clock is named 'scck', sensor controller clock. > + items: > + - const: pclk > + - const: scck > + > + ports: > + type: object > + description: > + List of ports > + > + properties: > + port@0: > + type: object > + description: > + Input port node, single endpoint describing the input pad. > + port@1: > + type: object > + description: > + Output port node, single endpoint, describing the output pad. That's a parallel video output, correct ? Does this port support any configurable property of the ones defined by video-interfaces.txt ? Thanks j > + > +additionalProperties: false > + > +required: > + - compatible > + - reg > + - clocks > + - clock-names > + - ports > + > +examples: > + - | > + csi2dc@e1404000 { > + compatible = "microchip,sama7g5-csi2dc"; > + reg = <0xe1404000 0x500>; > + clocks = <&pclk>, <&scck>; > + clock-names = "pclk", "scck"; > + > + ports { > + #address-cells = <1>; > + #size-cells = <0>; > + port@0 { > + reg = <0>; /* must be 0, first child port */ > + csi2dc_in: endpoint { /* input from IDI interface */ > + remote-endpoint = <&csi2host_out>; > + }; > + }; > + > + port@1 { > + reg = <1>; /* must be 1, second child port */ > + csi2dc_out: endpoint { > + remote-endpoint = <&xisc_in>; /* output to sensor controller */ > + }; > + }; > + }; > + }; > + > +... > -- > 2.25.1 >
