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From:   Alexander Stein <alexander.stein@ew.tq-group.com>
To:     jeanmichel.hautbois@ideasonboard.com,
        Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
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        dave.stevenson@raspberrypi.com, devicetree@vger.kernel.org,
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        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
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        lukasz@jany.st, mchehab@kernel.org, naush@raspberrypi.com,
        robh@kernel.org, tomi.valkeinen@ideasonboard.com,
        nsaenz@kernel.org, bcm-kernel-feedback-list@broadcom.com
Subject: Re: (EXT) [RFC PATCH v4 03/12] dt-bindings: media: Add bindings for bcm2835-unicam
Date:   Fri, 04 Feb 2022 09:50:06 +0100
Message-ID: <7954256.DvuYhMxLoT@steina-w>
Organization: TQ-Systems GmbH
In-Reply-To: <20220203175009.558868-4-jeanmichel.hautbois@ideasonboard.com>
References: <20220203175009.558868-1-jeanmichel.hautbois@ideasonboard.com> <20220203175009.558868-4-jeanmichel.hautbois@ideasonboard.com>
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Am Donnerstag, 3. Februar 2022, 18:50:00 CET schrieb Jean-Michel Hautbois:
> Introduce the dt-bindings documentation for bcm2835 CCP2/CSI2 Unicam
> camera interface. Also add a MAINTAINERS entry for it.
> 
> Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
> Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
> Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
> 
> ---
> 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@raspberrypi.com>
> +
> +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
> +  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.
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  clocks:
> +    items:
> +      - description: Clock to drive the LP state machine of Unicam.
> +      - description: Clock for the vpu (core clock).
> +
> +  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

There is already data-lanes in Documentation/devicetree/bindings/media/video-
interfaces.yaml. AFAICS these two are identical. Can't the video-
interface.yaml be used for this? I'm no expert TBH.

Regards,
Alexander