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Tue, 11 Aug 2026 13:31:00 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Tue, 11 Aug 2026 15:30:58 -0500 Message-Id: Cc: =?utf-8?q?Nuno_S=C3=A1?= , "Andy Shevchenko" , , , , Subject: Re: [PATCH v3 1/9] dt-bindings: iio: adc: support the TI ADS126x ADC family From: "Kurt Borja" To: "David Lechner" , "Kurt Borja" , "Jonathan Cameron" , "Rob Herring" , "Krzysztof Kozlowski" , "Conor Dooley" , "Linus Walleij" , "Bartosz Golaszewski" X-Mailer: aerc 0.21.0-0-g5549850facc2 References: <20260807-ads126x-v3-0-f89925d72792@gmail.com> <20260807-ads126x-v3-1-f89925d72792@gmail.com> In-Reply-To: On Mon Aug 10, 2026 at 11:42 AM -05, David Lechner wrote: > On 8/9/26 3:26 AM, Kurt Borja wrote: >> On Sat Aug 8, 2026 at 1:38 PM -05, David Lechner wrote: >>> On 8/7/26 10:58 PM, Kurt Borja wrote: >>>> The ADS1262 and ADS1263 are 32-bit, 38.4-kSPS delta-sigma ADCs with an >>>> integrated PGA, internal reference, excitation and burn-out current >>>> sources for sensor biasing and diagnostics. The ADS1263 adds a second, >>>> 24-bit delta-sigma ADC (ADC2) for background measurements. >>>> >>> >>> ... >>> >>>> +patternProperties: >>>> + "^ain([0-9]|com)-supply$": >>>> + description: >>>> + Common-mode voltage supply connected to AIN or AINCOM. >>>> + >>>> + "^refp[1-3]-supply$": >>>> + description: >>>> + Positive voltage reference connected to REFP1 (AIN0), REFP2 (AI= N2) or >>>> + REFP3 (AIN4). If not described, its assumed to be connected to = ground >>>> + (0V). >>> >>> Would we really have a case with a negative only reference? I would say= if not >>> described, assume the pin is free for other use. >>=20 >> In bipolar supply configurations, I believe it would make sense to wire >> the negative reference to -2.5V and ground the positive. Also we have >> the ti,reference-reversal case, where you may wire the "negative" >> reference to say 2.5V and the positive to ground. >>=20 > > OK. I guess the better wording for both of these would be that if any > channel references one of these in reference-sources and it is not presen= t > assume it is connected to ground (0V). I'll go for this wording. > >>> >>>> + >>>> + "^refn[1-3]-supply$": >>>> + description: >>>> + Negative voltage reference connected to REFN1 (AIN1), REFN2 (AI= N3) or >>>> + REFN3 (AIN5). If not described, its assumed to be connected to = ground >>>> + (0V). >>> >>> Assumption is only true when corresponding refp supply is described. Ot= herwise >>> we should assume the pin is free for other uses. >>=20 >> I'll clarify it. >>=20 >>> >>>> + >>>> + "^ti,refp[1-3]-refn[1-3]-resistor-ohms$": >>>> + description: >>>> + Magnitude of the external reference resistor connected between = REFP >>>> + and REFN. In ratiometric configurations, such as RTD measure= ments, the >>>> + IDAC excitation current returns through this resistor, generati= ng the >>>> + reference voltage for the conversion. >>>> + >>>> + "^channel@[0-9]+$": >>>> + $ref: /schemas/iio/adc/adc.yaml# >>>> + unevaluatedProperties: false >>>> + >>>> + properties: >>>> + reg: >>>> + maxItems: 1 >>>> + >>>> + single-channel: >>>> + minimum: 0 >>>> + maximum: 10 >>>> + >>>> + common-mode-channel: >>>> + minimum: 0 >>>> + maximum: 10 >>>> + default: 10 >>>> + >>>> + diff-channels: >>>> + description: | >>>> + In addition to the analog input pins 0 (AIN0) - 10 (AINCOM)= , there are >>>> + special inputs that can be selected from the following valu= es: >>>> + 11: Temperature sensor monitor >>>> + 12: Analog power supply monitor >>>> + 13: Digital power supply monitor >>>> + 14: TDAC test signal >>> >>> For reasons mentioned in the reply to the cover letter, I'm not a fan o= f the >>> monitor channels here. >>> >>>> + items: >>>> + minimum: 0 >>>> + maximum: 14 >>>> + >>> >>> ... >>> >>>> + input-chopping: true >>>> + >>>> + ti,idac-rotation: >>> >>> Should we make this one a standard property like input-chopping? >>=20 >> Maybe excitation-current-chopping or excitation-channel-chopping? > > I suppose. All of the TI literature seems to call it "rotation" rather > than "chopping", but I did find a few other sources that call it > "chopping" and that would be consistent with input-chopping. Yes, IMO it makes more sense to go for the chopping term. > > I would go with excitation-channel-chopping since we are swapping > the current generators, not just the current magnitude. I'll add the patch. --=20 Thanks, ~ Kurt