Re: [RFC PATCH v4 03/12] dt-bindings: media: Add bindings for bcm2835-unicam

[Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>]

Hi Jean-Michel,

Thank you for the patch.

On Thu, Feb 03, 2022 at 06:50:00PM +0100, Jean-Michel Hautbois wrote:
> Introduce the dt-bindings documentation for bcm2835 CCP2/CSI2 Unicam
> camera interface. Also add a MAINTAINERS entry for it.

You can drop the last sentence now that the MAINTAINERS entry has been
moved out.

> Signed-off-by: Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx>
> Signed-off-by: Naushir Patuck <naush@xxxxxxxxxxxxxxx>
> Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@xxxxxxxxxxxxxxxx>
> 
> ---
> v4:
> - make MAINTAINERS its own patch
> - describe the reg and clocks correctly
> - use a vendor entry for the number of data lanes
> ---
>  .../bindings/media/brcm,bcm2835-unicam.yaml   | 110 ++++++++++++++++++
>  1 file changed, 110 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml
> 
> diff --git a/Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml b/Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml
> new file mode 100644
> index 000000000000..0725a0267c60
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml
> @@ -0,0 +1,110 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/media/brcm,bcm2835-unicam.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Broadcom BCM283x Camera Interface (Unicam)
> +
> +maintainers:
> +  - Raspberry Pi Kernel Maintenance <kernel-list@xxxxxxxxxxxxxxx>
> +
> +description: |-
> +  The Unicam block on BCM283x SoCs is the receiver for either
> +  CSI-2 or CCP2 data from image sensors or similar devices.
> +
> +  The main platform using this SoC is the Raspberry Pi family of boards.
> +  On the Pi the VideoCore firmware can also control this hardware block,
> +  and driving it from two different processors will cause issues.
> +  To avoid this, the firmware checks the device tree configuration
> +  during boot. If it finds device tree nodes starting by csi then

"[...] device tree nodes whose name starts with 'csi' then [...]"

> +  it will stop the firmware accessing the block, and it can then
> +  safely be used via the device tree binding.
> +
> +properties:
> +  compatible:
> +    const: brcm,bcm2835-unicam
> +
> +  reg:
> +    items:
> +      - description: Unicam block.
> +      - description: Clock Manager Image (CMI) block.

As Stefan pointed out, you need

  reg-names:
    items:
      - const: main
      - const: cmi

Alternatives for main could be core or unicam. Dave, do you have a
preference ?

> +
> +  interrupts:
> +    maxItems: 1
> +
> +  clocks:
> +    items:
> +      - description: Clock to drive the LP state machine of Unicam.
> +      - description: Clock for the vpu (core clock).

s/vpu/VPU/

> +
> +  clock-names:
> +    items:
> +      - const: lp
> +      - const: vpu
> +
> +  power-domains:
> +    items:
> +      - description: Unicam power domain
> +
> +  brcm,num-data-lanes:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    enum: [ 2, 4 ]
> +    description: Number of data lanes on the csi bus

I'd write

    description: |
      Number of CSI-2 data lanes supported by this Unicam instance. The number
      of data lanes actively used is specified with the data-lanes endpoint
      property.

> +
> +  port:
> +    additionalProperties: false

Shouldn't this be unevaluatedProperties ?

I would also put it after the $ref line.

> +    $ref: /schemas/graph.yaml#/$defs/port-base
> +
> +    properties:
> +      endpoint:
> +        $ref: /schemas/media/video-interfaces.yaml#
> +        unevaluatedProperties: false
> +
> +        properties:
> +          data-lanes: true
> +          link-frequencies: true

link-frequencies is specified on the sensor side, not here. You can drop
it.

> +
> +        required:
> +          - data-lanes
> +          - link-frequencies
> +
> +    required:
> +      - endpoint
> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts
> +  - clocks
> +  - clock-names
> +  - power-domains
> +  - brcm,num-data-lanes
> +  - port
> +
> +additionalProperties: False
> +
> +examples:
> +  - |
> +    #include <dt-bindings/clock/bcm2835.h>
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +    #include <dt-bindings/power/raspberrypi-power.h>
> +    csi1: csi@7e801000 {
> +        compatible = "brcm,bcm2835-unicam";
> +        reg = <0x7e801000 0x800>,
> +              <0x7e802004 0x4>;
> +        interrupts = <GIC_SPI 103 IRQ_TYPE_LEVEL_HIGH>;
> +        clocks = <&clocks BCM2835_CLOCK_CAM1>,
> +                 <&firmware_clocks 4>;
> +        clock-names = "lp", "vpu";
> +        power-domains = <&power RPI_POWER_DOMAIN_UNICAM1>;
> +        brcm,num-data-lanes = <2>;
> +        port {
> +                csi1_ep: endpoint {

Wrong indentation.

> +                        remote-endpoint = <&imx219_0>;
> +                        data-lanes = <1 2>;
> +                        link-frequencies = /bits/ 64 <456000000>;

Drop link-frequencies here too.

With these small issues fixed,

Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>

> +                };
> +        };
> +    };
> +...

-- 
Regards,

Laurent Pinchart