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 0E3A4149C79; Fri, 23 Aug 2024 09:09:15 +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=1724404156; cv=none; b=I7sZSryRaUZDfhDaV5jC8zjYtw0e1N/2CKCiIrUk2azRzOJdgGvBwtygp24Ojn+rYVz1KjQtgwOP0+GSj9iSofoecXgAZufy8IzMavmiiubjGH/n5qg94rg6/ImCSYKTv/Z7ga3ma6WmqyqILPLCdFXTGSDYYO+qXZm1NLeGEp4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724404156; c=relaxed/simple; bh=pWVW/DKrRF/+sVlMcTSKkgOJkDnCjGIovyZ27nyrLs4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=i67b6GYADHwE33wgyM2MZI2HttMx6pCzZ/6lIouTmTdDHRZ/2k2Y4sbz3wAetIEjoiXrvqnNZUWY023UlyGzMboE53vm8a78JBJ9kMSd5qdri4vpFP0J1+AjWXy4dZ0kV/ew1kMgJol4MJxVcO/g4qc3Fi9MaIdx/R8yF5LNG5g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OCgt+uDS; 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="OCgt+uDS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AD55EC32786; Fri, 23 Aug 2024 09:09:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724404155; bh=pWVW/DKrRF/+sVlMcTSKkgOJkDnCjGIovyZ27nyrLs4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=OCgt+uDS0N2lw/qclh3LAkT4zfKSNtONT9mnxq5NzY24VfaIngVmwtcrfR89wq/i+ XnU/A1beEmk8w+IeYvHFwKwGwTuNpi0T4AyLpIiOpSCi79yX+Uanp053iwoag9vlpT CSJpEe1Qt7UjN03+QqC7t0S7LdA1gVwsagDaNUScXJNEijwXhrtC0/ItB4mpDYtlVr +P0XHwcCjEIE76G6UkKHRwlugabef48VxDUVEjpPmAOuzFQbCdSrVnhTTKh7vHyGEw uBN+uEphEKEGl979evy9IROdaO00MsUAupdLx2hS1DIK+i0ZqTDCzxN76vKyJHyWhp Z7aTsaF48Ki1g== Message-ID: <46153017-9ab2-4a2f-afe6-9321e0f65f03@kernel.org> Date: Fri, 23 Aug 2024 11:09:08 +0200 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 6/7] dt-bindings: iio: adc: add adi,ad7606c-{16,18} compatible strings To: Jonathan Cameron , Alexandru Ardelean Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, krzk+dt@kernel.org, robh@kernel.org, lars@metafoo.de, michael.hennerich@analog.com, gstols@baylibre.com References: <20240819064721.91494-1-aardelean@baylibre.com> <20240819064721.91494-7-aardelean@baylibre.com> <20240821212606.6981eae1@jic23-huawei> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 21/08/2024 22:26, Jonathan Cameron wrote: > >>>> + type: object >>>> + $ref: adc.yaml >>>> + unevaluatedProperties: false >>>> + >>>> + properties: >>>> + reg: >>>> + description: The channel number. >>>> + minimum: 0 >>>> + maximum: 7 >>>> + >>>> + diff-channel: >>>> + description: Channel is bipolar differential. >>> >>> There is diff-channels property, why do we need one more? >> >> Yeah, I wanted to use that. >> Maybe I will try another spin at that. >> The thing with "diff-channels" is that it requires 2 ints. >> So, diff-channels = <0 0>. >> To use it here, a rule would need to be put in place where "reg == >> diff-channels[0] && reg == diff-channels[1]". >> That also works from my side. >> Part of the reason for this patchset, was to also get some feedback >> (if this is the correct direction). >> > So I 'think' this is a datasheet matching thing. > In many cases, even for strictly differential devices, the pin > naming allows for a clear A - B channel description. Here > in the non differential modes, the negative pins are effectively > not used (from a really quick look at the datasheet) > > So we 'could' introduce magic channels (give them high numbers) for > the negative ends. I think we may want to do that for the > userspace ABI (0-0 on the few times it has come up has been a > calibration / self check mode not what you have here - it > wires the actual inputs together). Alternative is just present > them as a simple voltage and don't worry about the differential aspect > as it's not hugely different to bipolar (where the zero level is > effectively the negative input of a differential ADC. > > For the binding I'm fine with the binding using A, A as you suggest > with an update to adc.yaml to cover this corner. Yep, let's add it to adc.yaml. > > We never (I think) have bindings for the self check case where the input > is wired to both sides. It's just a mode that is applied to > any inputs that are wired. > Best regards, Krzysztof