From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D8D674A8FF7; Wed, 16 Sep 2026 13:41:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789566096; cv=none; b=Nnyw//4BHSSrnAcQJXoh5UgDQMtZ0J1JUGpe79fSgLX7BFnxyUjwVBaRcXfp9eeMj8gszFhshghu8QG3xnf/Avhp/+OvtHz6nrRDExjKyi0MHY3LpeqhsPYEkt8GL9VNrUzScUudQ1OqN2ZVm92ZPqoZl/GTRdWx1RobrZHzbKI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789566096; c=relaxed/simple; bh=Y23TEL4VWjKk050EFd+EMGfECRJpcBc/J1ICpp2a8AI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=eHskPlc336nG6v6816cXD+9Kj4DwJHp4QbznZRM/0pAYytbzsV8sSh2orvRI7of9R6P6wYN85kMurXXNH4puz/zGgvO02ZPL52udAITQDa3WzC5lXhPmkPUESsN6bglSYHKrMEcg3fPA/5Qymt/eFfNjZ9sW1e3c98THusfFunU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LEPFaEgt; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LEPFaEgt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 532331F000FF; Wed, 16 Sep 2026 13:41:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789566083; bh=ty9HMdXm16jh0iP7vayc+uF466KQcdah8P1bvXP44aE=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=LEPFaEgt6q0wI/3g+F7g5JB59ceU28bS71D9rlo/TgyOvOPdq6tngHXVAp5PIrjfo PZdeE+4F89B/p8qpwwn4iPGTVxh55iZkfso0rEPHVwYvghgRVy2rlDziRgzyjxEPRJ BAS09hfxkS8bUzwoyM+Oirvz7l5CuzA0mOhCpY6HIVUNNY4FUZIzCrBeCWgIlQJjYJ oUSh0WsEDReUhKFzZ1h7gCQVLpxWXu6K6M1nl5IcZJTWiV4p7NzjxjDPa4vYRhKDIF ARSyizhnC9X1BjGy4CE/XgbZgzNwXJCNNXBV04IT92kX1Bhi2klOUXrVeab/5vHKsH 5w4MU3NXIiOLw== Message-ID: Date: Wed, 16 Sep 2026 15:41:16 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/3] dt-bindings: media: i2c: Add vision-components,mipi-module-controller To: Richard Leitner Cc: Rob Herring , Krzysztof Kozlowski , Conor Dooley , Mauro Carvalho Chehab , Laurent Pinchart , Alexander Stein , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org References: <20260915-vc-mipi-ctrl-v1-0-8a42b693d889@linux.dev> <20260915-vc-mipi-ctrl-v1-2-8a42b693d889@linux.dev> <20260916-daft-relaxed-mouse-9bfaf4@quoll> <45fd8255-6ba8-4488-acc8-4f7fc9c85ade@kernel.org> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 16/09/2026 11:01, Richard Leitner wrote: > On Wed, Sep 16, 2026 at 10:35:22AM +0200, Krzysztof Kozlowski wrote: >> On 16/09/2026 09:33, Richard Leitner wrote: >>> Hi Krzysztof, >>> >>> thanks for the review! >>> >>> On Wed, Sep 16, 2026 at 09:00:46AM +0200, Krzysztof Kozlowski wrote: >>>> On Tue, Sep 15, 2026 at 10:20:24PM +0200, Richard Leitner wrote: >>>>> Add bindings for the Vision Components MIPI Camera Module Controller. >>>>> >>>>> Signed-off-by: Richard Leitner >>>>> --- >>>>> .../vision-components,mipi-module-controller.yaml | 92 ++++++++++++++++++++++ >>>>> MAINTAINERS | 7 ++ >>>>> 2 files changed, 99 insertions(+) >>>> >>>> This fails tests, so a very brief review / a few comments: >>> >>> Mea culpa, I simply failed to run the dtb check before submitting. Sorry. >>> Will not happen again. >>> >>>> >>>>> >>>>> diff --git a/Documentation/devicetree/bindings/media/i2c/vision-components,mipi-module-controller.yaml b/Documentation/devicetree/bindings/media/i2c/vision-components,mipi-module-controller.yaml >>>>> new file mode 100644 >>>>> index 0000000000000..2a031aea68457 >>>>> --- /dev/null >>>>> +++ b/Documentation/devicetree/bindings/media/i2c/vision-components,mipi-module-controller.yaml >>>>> @@ -0,0 +1,92 @@ >>>>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) >>>>> +%YAML 1.2 >>>>> +--- >>>>> +$id: http://devicetree.org/schemas/media/i2c/vision-components,mipi-module-controller.yaml# >>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml# >>>>> + >>>>> +title: Vision Components MIPI Camera Module Controller >>>>> + >>>>> +maintainers: >>>>> + - Laurent Pinchart >>>>> + - Richard Leitner >>>>> + >>>>> +description: |- >>>>> + The MIPI camera module controller is an FPGA-based, I2C-accessible system >>>>> + controller found on MIPI camera modules from Vision Components. It abstracts >>>>> + the camera sensor behind a unified register interface, and controls and >>>>> + sequences the on-board power supplies and clocks. >>>>> + >>>>> + The camera sensor abstraction is optional. The controller exposes a tunneled >>>>> + downstream I2C bus used by the attached image sensor. The controller node >>>>> + acts as the upstream device on the host bus, while child node below the >>>>> + controller represent the sensor device reachable through the tunnel. >>>>> + >>>>> +properties: >>>>> + compatible: >>>>> + const: vision-components,mipi-module-controller >>>> >>>> There is no model name, no version, nothing identifying it better? >>>> Compatible must be specific to the device (see also writing bindings). >>> >>> There is one FPGA implemenation for all Vision Components MIPI camera >>> modules AFAICT. So I have no idea how it could be more specific, TBH... >>> >>> Adding the FPGA hardware model/type is wrong IMHO as it depends on its >>> configuration/firmware, not the hw. >>> >>> There are different versions of the configuration/firmware. But I think >>> this is also not the correct way to distinguish those, or is it? >>> >>> According to their homepage the vendor calls those modules simply >>> "VC MIPI" modules, which implies this FPGA controller is available on it. >>> So maybe "vision-components,vc-mipi-controller" would be a better fit? >>> >>> Do you have any ideas/feedback on how improve this name? >> >> So there are different modules? I see several different names on: >> https://www.mipi-modules.com/en/mipi-camera-modules/ > > Yes, there are different modules, but all feature the same controller. > Which this is basically the device driver binding for. So the idea is to > describe the controller independently from the sensor which is "behind" > it. > > This works because the controller "soft-core" should be the same on all > modules. A downstream implemenation (which I haven't studied in detail) > is available at https://github.com/VC-MIPI-modules/vc_mipi_core if that > helps? > >> >> >>> >>>> >>>>> + >>>>> + reg: >>>>> + maxItems: 1 >>>>> + >>>>> + '#clock-cells': >>>>> + const: 0 >>>>> + >>>>> + clock-frequency: >>>>> + description: Frequency of the sensor clock provided by the module >>>> >>>> Drop, implied by the compatible >>>> >>> >>> Do you mean dropping the whole property, or just the "description"? >> >> I meant entire property, but we keep discussing in Laurent's reply. >> >>> >>>>> + >>>>> + vcc-supply: >>>>> + description: Power supply of the module (3.3V) >>>>> + >>>>> + '#address-cells': >>>>> + const: 1 >>>>> + >>>>> + '#size-cells': >>>>> + const: 0 >>>> >>>> No children allowed, so why these two? >>> >>> Based on your and the bot feedback I would suggest for v2 to change this >>> "generic i2c bus" to a simple "i2c-tunnel" property which has >>> "$ref: /schemas/i2c/i2c-controller.yaml". >>> >>> This would better reflect the actual hardware, as there is only this one, >>> in firmware hard-coded I2C downstream bus. >>> >>> Would this be a sane approach? >> >> If the underlying I2C bus and sensor are important, then yes. But I have >> doubts that you need to describe the sensor if it is truly >> unadressable/invisible to the OS. > > Yes, the I2C bus and sensor is important. The device driver of the sensor > talks (via the tunneled I2C interface) directly to the sensor. > > The separate I2C controller/bus description is necessary as the tunneled > I2C bus has some quirks unfortunately. Those need to be addressed as > otherwise the sensor drivers do not work. > > So the idea is to not have a vc-mipi module binding per "sensor variant" > of the camera modules, but provide a common controller driver which > provides the I2C bus for the sensor driver. Bindings must accurately describe the device and so far - based on the website - there is no device as mipi-module-controller alone. I don't get why you assume that all of the variants are exactly identical, thus sensor variant is not applicable. If they are identical in all aspects, then why clock-frequency property? That's obviously rhetorical question, because they are not identical in all aspects and must produce different clock at least. > >> >>> >>>> >>>>> + >>>>> +required: >>>>> + - compatible >>>>> + - reg >>>>> + - '#clock-cells' >>>>> + - clock-frequency >>>>> + - vcc-supply >>>>> + - '#address-cells' >>>>> + - '#size-cells' >>>>> + >>>>> +unevaluatedProperties: false >>>> >>>> additionalProperties instead, see writing bindings or writing schema. >>>> Unless you miss here some other schema $ref. >>>> >>>>> + >>>>> +examples: >>>>> + - | >>>>> + i2c { >>>>> + #address-cells = <1>; >>>>> + #size-cells = <0>; >>>>> + >>>>> + vc_mipi_ctrl: controller@10 { >>>>> + compatible = "vision-components,mipi-module-controller"; >>>>> + reg = <0x10>; >>>>> + #clock-cells = <0>; >>>>> + clock-frequency = <37125000>; >>>>> + vcc-supply = <&cam_3v3>; >>>>> + >>>>> + #address-cells = <1>; >>>>> + #size-cells = <0>; >>>>> + >>>>> + i2c@0 { >>>>> + #address-cells = <1>; >>>>> + #size-cells = <0>; >>>>> + >>>>> + vc_mipi_sensor: camera@60 { >>>>> + compatible = "ovti,ov9281"; >>>>> + reg = <0x60>; >>>> >>>> Why having the child abstraction if it is completely abstracted? I don't >>>> fully get the explanation from description. Completely optional means no >>>> benefits, no point in it, no? >>> >>> I will try to improve the description. The idea behind this device >>> driver/devicetree node is to not rely on the sensor abstraction from >>> vision components, but to use the upstream sensor specific driver. >> >> You can use driver even without these nodes... but fine, let's assume >> you have them, so driver will talk with OV9281 sensor for example? > > The vc-mipi driver does not talk to sensor at all. This is done by the > dedicated sensor driver. The vc-mipi driver is only controlling the > regulator, clock, etc. as described and sets up the "quirk aware" > tunneled i2c interface. I meant, driver for the sensor. So who controls sensor supplies? Not the sensor driver? It tells something how the hardware is managed, no? > Best regards, Krzysztof