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([2600:8803:e7e4:500:e190:78b2:dd4e:ba94]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-7e9ec2ba18esm2689450a34.16.2026.06.30.08.24.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 30 Jun 2026 08:24:19 -0700 (PDT) Message-ID: Date: Tue, 30 Jun 2026 10:24:19 -0500 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 1/2] dt-bindings: iio: adc: ti,ads1298: add ADS1299 EEG ADC variants To: Md Shofiqul Islam , linux-iio@vger.kernel.org Cc: jic23@kernel.org, nuno.sa@analog.com, andy@kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, mike.looijmans@topic.nl, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260630140311.1473031-1-shofiqtest@gmail.com> Content-Language: en-US From: David Lechner In-Reply-To: <20260630140311.1473031-1-shofiqtest@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/30/26 9:03 AM, Md Shofiqul Islam wrote: > The ADS1299, ADS1299-4, and ADS1299-6 share the same SPI interface > and register map as the ADS1298 ECG ADC family but are designed for > EEG and biopotential measurement. Key differences from ADS1298: > - PGA gain up to 24x (vs 12x for ADS1298) > - Internal reference is always 2.4V (no 4V option) > > Add compatible strings and update the vref-supply description to > document the ADS1299 reference voltage behaviour. > > Signed-off-by: Md Shofiqul Islam > --- > .../bindings/iio/adc/ti,ads1298.yaml | 31 ++++++++++++++++--- > 1 file changed, 26 insertions(+), 5 deletions(-) > > diff --git a/Documentation/devicetree/bindings/iio/adc/ti,ads1298.yaml b/Documentation/devicetree/bindings/iio/adc/ti,ads1298.yaml > index 71f9f9b745cb..82c5181126df 100644 > --- a/Documentation/devicetree/bindings/iio/adc/ti,ads1298.yaml > +++ b/Documentation/devicetree/bindings/iio/adc/ti,ads1298.yaml > @@ -4,11 +4,16 @@ > $id: http://devicetree.org/schemas/iio/adc/ti,ads1298.yaml# > $schema: http://devicetree.org/meta-schemas/core.yaml# > > -title: Texas Instruments' ads1298 medical ADC chips > +title: Texas Instruments ADS1298/ADS1299 biopotential ADC chips > > description: | > - Datasheet at: https://www.ti.com/product/ADS1298 > - Bindings for this chip aren't complete. > + ADS1298/ADS1298R: 8-channel, 24-bit ECG ADC. > + Datasheet: https://www.ti.com/product/ADS1298 > + > + ADS1299/ADS1299-4/ADS1299-6: 8/4/6-channel, 24-bit EEG/biopotential ADC. > + Identical SPI interface and register map to the ADS1298 family, but with > + a higher maximum PGA gain (24x vs 12x) and fixed 2.4V internal reference. > + Datasheet: https://www.ti.com/product/ADS1299 > > maintainers: > - Mike Looijmans > @@ -17,6 +22,9 @@ properties: > compatible: > enum: > - ti,ads1298 > + - ti,ads1299 > + - ti,ads1299-4 > + - ti,ads1299-6 > > reg: > maxItems: 1 > @@ -33,8 +41,10 @@ properties: > > vref-supply: > description: > - Optional reference voltage. If omitted, internal reference is used, > - which is 2.4V when analog supply is below 4.4V, 4V otherwise. > + Optional reference voltage. If omitted, internal reference is used. > + For ADS1298, the internal reference is 2.4V when analog supply is > + below 4.4V, 4V otherwise. For ADS1299, the internal reference is > + always 2.4V. Not sure the dt-bindings care about the internal reference. It should just be a driver implementation detail. So I would just trim this down to: Optional reference voltage. If omitted, internal reference is used. > > clocks: > description: Optional 2.048 MHz external source clock on CLK pin > @@ -75,5 +85,16 @@ examples: > spi-max-frequency = <20000000>; > spi-cpha; > }; > + > + adc@2 { > + reg = <2>; > + compatible = "ti,ads1299"; > + label = "ads1299-1-eeg"; > + avdd-supply = <®_iso_5v_a>; > + interrupt-parent = <&gpio0>; > + interrupts = <79 IRQ_TYPE_EDGE_FALLING>; > + spi-max-frequency = <20000000>; > + spi-cpha; > + }; Since the chips are nearly identical, not sure a 2nd example is particularly useful. > }; > ...