Re: [PATCH v5 1/3] dt-bindings: media: atmel: csi2dc: add bindings for microchip csi2dc

[Eugen.Hristev]

On 17.11.2020 12:37, Jacopo Mondi wrote:
> Hi again,
> 
> 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.
>> +  For media entity and endpoints please refer to the bindings defined in
>> +  Documentation/devicetree/bindings/media/video-interfaces.txt.
>> +  For Synopsys IDI interface please refer to
>> +  Documentation/devicetree/bindings/media/snps,dw-csi-plat.txt
> 
> Is it me or this file doesn't exists on the most recent media/master
> and on v5.10-rc4 ?

Hi Jacopo,

Thanks for reviewing this patch.
You are right. As I said at some point during the review, actually this 
controller has an input the IDI interface which is not currently in 
kernel. There is a patch series that adds the Synopsys platform driver, 
but nobody worked on it anymore and I use it for testing my driver.
You can see the last version that was sent here:

https://patchwork.linuxtv.org/project/linux-media/patch/1560280855-18085-2-git-send-email-luis.oliveira@xxxxxxxxxxxx/ 


I sent this series to understand how to improve and how to get my driver 
in kernel, but indeed there are holes, especially this input type of bus 
which is not in the subsystem either.

So how would you suggest to move forward ? Remove the reference to the 
synopsys binding and just leave 'IDI interface' which is undocumented ?

Eugen

> 
>> +
>> +  CSI2DC supports one 'port' node as sink pad with parallel interface. This is
>> +  called video pipe.
>> +  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.
>> +  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.
>> +
>> +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.
>> +
>> +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
>>