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 3C0A43B27EE; Wed, 1 Jul 2026 09:44:17 +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=1782899058; cv=none; b=IfJ3VHhUkJ9Oroej/iTaC2t6FCgS3ph52Mc0UdU/MZUejMXbWX0IET2bp2e9bJGMzyBRocffWY2Ama4K2fhOEUUvUALxZbvoflvCDwcte7FTB8ohmy80Sj+9J17UxWf4TV6X696PUDt43wHmwCT75hJHjeINdDCDCCV3kI8yJl4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782899058; c=relaxed/simple; bh=L6gkE72ufhclaMsI9upfCCNyGuXGgsjo3LbkP0RV2nk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Razp98PZF0S8TUBGg3wtHNi9BJsVkkAqS1T/R51WhoBexkzCPm6wwT/+yRuZlG1AN2kQf1WA5QUAxDsxuMuR//g9gUP+o+E9zhBIiDjlLpMtU2k/vC//+TqhqHabLmd6Cc89GrBblfuRNVkEF2BastJtDbu0+7Ux9w/G4CoQOpk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BoKche5Z; 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="BoKche5Z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D11781F000E9; Wed, 1 Jul 2026 09:44:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782899057; bh=pdPYIL3HALxZogHYg0wjFJy2CbGUybJni4StUn9EnZo=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=BoKche5ZxfRqJ9lbhZ1h7tEhVaEhxuOvJPRI2Vauwh8RZw5BhkISbdiJGOiyjHOYZ 0vjdkZWVL8bORczFhKTZmzCLdfpYj8YQOFUEJNVyn/Lw1gx2o8pQ1CVHEhAkAq7XBx t+7YnM88YthN0QEly28funTYqOsCfvOyuJp9JPVnk11wGkc8nb8f8Z+9UOet80cejX vh8pcIYToGdadBHc7E0hQ3oPudIA4waAQCiHQZvfhY86Cr4RG3sP3+rIxk3PLPcd1V akHtJUazJuqPm5UktfVPA55tHjfun62zimeIslcUIvDxbcM0hfB5GFhz0M6oErImFK aW2BkXA8mjL4Q== Date: Wed, 1 Jul 2026 10:44:12 +0100 From: Conor Dooley To: Jonathan Cameron Cc: Md Shofiqul Islam , linux-iio@vger.kernel.org, dlechner@baylibre.com, 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 Subject: Re: [PATCH 1/2] dt-bindings: iio: adc: ti,ads1298: add ADS1299 EEG ADC variants Message-ID: <20260701-relic-urologist-87fd855061cf@spud> References: <20260630140311.1473031-1-shofiqtest@gmail.com> <20260701001428.1670e3cc@jic23-huawei> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="RoLiFFBC7RdAvuci" Content-Disposition: inline In-Reply-To: <20260701001428.1670e3cc@jic23-huawei> --RoLiFFBC7RdAvuci Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jul 01, 2026 at 12:14:28AM +0100, Jonathan Cameron wrote: > On Tue, 30 Jun 2026 17:03:10 +0300 > Md Shofiqul Islam wrote: >=20 > > 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) > >=20 > > Add compatible strings and update the vref-supply description to > > document the ADS1299 reference voltage behaviour. > >=20 > > Signed-off-by: Md Shofiqul Islam >=20 > > =20 > > maintainers: > > - Mike Looijmans > > @@ -17,6 +22,9 @@ properties: > > compatible: > > enum: > > - ti,ads1298 > > + - ti,ads1299 > > + - ti,ads1299-4 > > + - ti,ads1299-6 >=20 > As the channel count is a discoverable feature (encoded as a field in the > ID Register, I think we can use just the one compatible). FWIW it is > nice to see a manufacturer making this discoverable! I'd expect any > future drop in parts to vary the other part of the ID, but this field > should be respected - as such this doesn't fall into the stuff I've been > discussing with DT maintainers about fallback compatibles needing to > be specific (I'm way behind so not sure where that thread got to!) I forget that thread too, but I think the difference is discoverable ID versus discoverable capabilities. If you match on a generic compatible with a new discoverable ID you've got no idea how to handle it. Matching on an existing specific compatible with a new ID, you treat it as the existing device. Matching on a generic compatible with the ability to discover the channel count, you know what to do. --RoLiFFBC7RdAvuci Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCakThbAAKCRB4tDGHoIJi 0qvMAQCJ69bB5L3ocBA6VKhb4Wr9dF1buVfCYfzqkr76eKFUrQEA7LN3v7YQXcuW Q0UlZmdAvhGtveWrDdS/gRU8P7DlWAI= =ZT6k -----END PGP SIGNATURE----- --RoLiFFBC7RdAvuci--