From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 D21A939B971; Wed, 25 Mar 2026 13:44:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774446257; cv=none; b=QIxe0doP55mRADx9Te4mLdxrw26nV46juN4Tyv+R3B3HEeHEzetmx4JTOcwnOzkYUhx3y/BkpCrFyMkrEfmzC5yOwG7GFA9nLsByULhSLxfWkWKOFfUNiwu5VYKHh+Ykk9OA5w61nlP/CJHRvqOKkAHSqyCrYvntcnqHFbF0x1w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774446257; c=relaxed/simple; bh=aVeXl96fDbGRyWT9TuYudXskoTKKztaf86ZZMUJH2uY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=WLI4L4zZ50YTw4BQvuosdRb3PKD9YqglamTX7VGFrKS6/gC7VrlgvnpGFOzzeNWPrUIqx49pyjiR5DdoAcBPlViWccEKXsgcx0l0F0HjMS736AzllHBVeO96dqbvEeRHVj/eRLfPB3hDp6ryl0HLdQrBUU2chQMoNbLiDcf2XnE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=p4AihPRo; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="p4AihPRo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DD68BC2BCB2; Wed, 25 Mar 2026 13:44:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774446257; bh=aVeXl96fDbGRyWT9TuYudXskoTKKztaf86ZZMUJH2uY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=p4AihPRowNRLIXM9svfzj3qzeKVnNy5WH65pGvsiAxcbQeXP0oQGRXwiI+aCheJTz wDXHlIeARdHnYZrA9nAtz/3RbZxsNrAXhLCCVBtwl+xx9stzvo8D2M8H9w++fDGREv e9lg/m8rOwKgVLbSHFGmqC+XsOTj/xzCpTtZAMqkuGlO8fA5H9YugXKEEiZ2mKHJuc bBWciyOpVs2o0w4WtwqAy38tM/Ik96po/+IDRo5ONUiSnhERevFyVcBpBA9pdmPeK1 HYmdNeP29gvJ8nrZs8WqfmLx7Q2dl9ImlvRzbHUWO/DBKW9fLWRmaG24s8PD5dekbc jywatYRKKItIw== Message-ID: Date: Wed, 25 Mar 2026 14:44:13 +0100 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 1/2] dt-bindings: iio: proximity: add ST VL53L1X ToF sensor To: Jonathan Cameron , Sirat Cc: linux-iio@vger.kernel.org, devicetree@vger.kernel.org, jic23@kernel.org, dlechner@baylibre.com, nuno.sa@analog.com, andy@kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, linux-kernel@vger.kernel.org References: <20260325063254.18062-1-email@sirat.me> <20260325063254.18062-2-email@sirat.me> <20260325-gentle-earthworm-of-progress-1f9f46@quoll> <4d10b6c0-d599-4fc5-b9ed-ce669ac46e84@kernel.org> <20260325133806.00007b68@huawei.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 25/03/2026 14:38, Jonathan Cameron wrote: > On Wed, 25 Mar 2026 15:18:05 +0600 > Sirat wrote: > >> On Wed, Mar 25, 2026 at 2:58 PM Krzysztof Kozlowski wrote: >>> >>> On 25/03/2026 09:48, Sirat wrote: >>>> On Wed, Mar 25, 2026 at 2:05 PM Krzysztof Kozlowski wrote: >>>>> >>>>> On Wed, Mar 25, 2026 at 12:32:22PM +0600, Siratul Islam wrote: >>>>>> Add device tree binding documentation for the STMicroelectronics >>>>>> VL53L1X Time-of-Flight ranging sensor connected via I2C. >>>>>> >>>>>> Make vdd-supply required. The device requires power to operate >>>>>> and the property should have been required from the start. >>>>> >>>>> That's ABI break and device for many years was working fine, so this >>>>> should not be changed. >>>>> >>>> Jonathan and David asked that vdd-supply be made required. I feel like >>>> there is a conflict here that I am not able to resolve myself. >>>> >>>> What I think about it is the binding does not correctly describe the >>>> hardware and we should consider this a bug and fix it. >>>> The driver worked because of a fallback mechanism (dummy/fake >>>> regulator) and not because power was optional. >>>> >>> >>> >>> I looked at v6 and v5 and I do not see such comment for binding that >>> existing device should change ABI. Can you point me to it? >>> >> "Make it required and add a note to the commit message to say why the >> requirement should always have been there. Devices tend not to work >> with no power." - Jonathan (v3: >> https://lore.kernel.org/linux-iio/20260322115704.10b2e0d4@jic23-huawei) >> >> "No, bindings should not depend on driver implementation." - David >> (When I asked if I should drop the hard requirement in the binding, >> v6: https://lore.kernel.org/linux-iio/55e92148-b5de-4fb8-af0b-9476235341bc@baylibre.com/) >> >> "From the point of view of the devicetree, it doesn't matter what the >> driver does. It matters that the chip can't work without power. ;-)" - >> David (v1: https://lore.kernel.org/linux-iio/d0ec6a2f-6d30-4774-8950-15dd3c4b020b@baylibre.com) >> >> I'm not sure if this is the correct way to quote. But I have added the links. > > This came up a few years back - though I doubt I can track down the > exact discussion however. > > From a Linux point of view we are breaking binding checks only if the > supply (that should always have been there as chips tend not to work > well without power) is not present. We absolutely have to > keep the driver running whether or not the supply is specified. > Do other DT users provide such a constraint? I've no idea. > > If the DT maintainer preference is leave it not required (perhaps > with a comment saying new users of the binding should supply it) > then that's fine by me. I'll keep it in mind for future similar changes. If this was other ABI, e.g. clock, then answer would be - do not require it, because that's ABI break. Therefore I would stick to that also to regulators. Once Rob also expressed such thoughts, although noting that it is not that big deal. New device in this binding of course should require the supply. Best regards, Krzysztof