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 9553D324B06; Wed, 28 Jan 2026 17:00:15 +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=1769619615; cv=none; b=Se8tuudGdJ314qC9XIpYOYiGTxzE2nY4dyB6vVKRptiS2h4ITvjjDFb0uU2FH7/tZj+DW8JQWsBxpr3nNwjeOQ1lKLnqnOG3rnr2/mnxD1RxFSciewNlOJkiRwVHQlWcduIhQIW0dCKN/btCzVxm3IIQKC63hLcoLVLwWYjwkxA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769619615; c=relaxed/simple; bh=vyPijSiORLrhf1vw8XfUJJuj6sjnbOIb/14ClasAikU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jDEHtno64N72zkv9QDL4dEfhqkLvj8wI6Aa1UFUAD0mMGqkiJYe11KatTYAjD/xLRfdis9wNDX9hz8AxuJ9c9aMdEKbh8WzJYKg2LJirsyP65PxXO0CuYrTyLXu1E70mgNmJpRhsgumq4ecPR/MPeaAK0yGGo9QKWwFa4CWk020= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Owcsb6Gn; 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="Owcsb6Gn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ABEB7C4CEF1; Wed, 28 Jan 2026 17:00:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769619615; bh=vyPijSiORLrhf1vw8XfUJJuj6sjnbOIb/14ClasAikU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Owcsb6GnWtzfdY6z+v3eDATFep3K4bF0Hd09BiEFyNsjArbt0ODIFhX8PGXxVk512 ur6ESHMAcEleL5EI9g+t2zk9+qQz8VCtfWYLXAmT+7EhJeDmvDJp7h6yhngrAWxKpW 7ohPXYtLV2pntprsn4K1JNEW2fM3rUCEvXgV5wIThTMCKd31eebu3o35oLFzaOqVnp MNVcSqwd8kDlUBSdM0vqiSEkF/RONY28vulehojAOuwVQb7rbkjdkSVeT8asvQ0Usr EKEs+H9G4oB6Jzm3zJ4ZivRXUn2zWlUxBzjNicLjnxEIAIOL8wpSCgMwigI13Atpzo eRdkeLmp4XUBg== Date: Wed, 28 Jan 2026 17:00:10 +0000 From: Conor Dooley To: David Jander Cc: Oleksij Rempel , Jonathan Cameron , Rob Herring , Krzysztof Kozlowski , Conor Dooley , kernel@pengutronix.de, linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, devicetree@vger.kernel.org, Andy Shevchenko , David Lechner , Nuno =?iso-8859-1?Q?S=E1?= Subject: Re: [PATCH v2 2/8] dt-bindings: iio: dac: maxim,ds4424: add maxim,rfs-ohms property Message-ID: <20260128-omit-bubbling-9224777f4071@spud> References: <20260127060939.3914006-1-o.rempel@pengutronix.de> <20260127060939.3914006-3-o.rempel@pengutronix.de> <20260127-consonant-vividness-13707c7cf8f6@spud> <20260127-rockiness-finalize-e0b50b9d823f@spud> <20260128090118.5c1d7906@erd003.prtnl> Precedence: bulk X-Mailing-List: linux-iio@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="m6BRV1LwaCRhnwbk" Content-Disposition: inline In-Reply-To: <20260128090118.5c1d7906@erd003.prtnl> --m6BRV1LwaCRhnwbk Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jan 28, 2026 at 09:01:18AM +0100, David Jander wrote: > On Tue, 27 Jan 2026 19:55:26 +0000 > Conor Dooley wrote: >=20 > > On Tue, Jan 27, 2026 at 07:49:20PM +0000, Conor Dooley wrote: > > > On Tue, Jan 27, 2026 at 07:09:33AM +0100, Oleksij Rempel wrote: =20 > > > > The Maxim DS4422/DS4424 and DS4402/DS4404 current DACs determine th= eir > > > > full-scale output current via external resistors (Rfs) connected to= the > > > > FSx pins. Without knowing these values, the full-scale range of the > > > > hardware is undefined. > > > >=20 > > > > Add the 'maxim,rfs-ohms' property to describe these physical compon= ents. > > > > This property is required to provide a complete description of the > > > > hardware configuration. > > > >=20 > > > > Signed-off-by: Oleksij Rempel > > > > --- > > > > changes v2: > > > > - make maxim,rfs-ohms a required property as the hardware range is = undefined > > > > without external resistors. > > > > - add allOf constraints to enforce 2 vs 4 items in maxim,rfs-ohms b= ased on > > > > compatible string. > > > > - drop explicit $ref for maxim,rfs-ohms to fix dt_binding_check war= ning. > > > > - update example in binding to include the new required property. > > > > --- > > > > .../bindings/iio/dac/maxim,ds4424.yaml | 36 +++++++++++++++= ++++ > > > > 1 file changed, 36 insertions(+) > > > >=20 > > > > diff --git a/Documentation/devicetree/bindings/iio/dac/maxim,ds4424= =2Eyaml b/Documentation/devicetree/bindings/iio/dac/maxim,ds4424.yaml > > > > index efe63e6cb55d..400afd8771aa 100644 > > > > --- a/Documentation/devicetree/bindings/iio/dac/maxim,ds4424.yaml > > > > +++ b/Documentation/devicetree/bindings/iio/dac/maxim,ds4424.yaml > > > > @@ -27,9 +27,44 @@ properties: > > > > =20 > > > > vcc-supply: true > > > > =20 > > > > + maxim,rfs-ohms: > > > > + description: | > > > > + Array of resistance values in Ohms for the external Rfs resi= stors > > > > + connected to the FS pins. > > > > + - For DS44x2 (2 channels): 2 values required. > > > > + - For DS44x4 (4 channels): 4 values required. > > > > + Typical values range from 40000 (40 kOhm) to 160000 (160 kOh= m). =20 > > >=20 > > > Add here > > > maxItems: 4 > > > minItems: 2 > > >=20 > > > Are 40kOhm and 160kOhm actual max/min values, or just a suggested ran= ge? =20 > >=20 > > Datasheet for the ds4424 seems to imply they're actual max/min values: > > "Input resistors (RFS) must be between the speciifed values to ensure t= he > > device meets its accuracy and linearity specifications." > > In that case, consider also adding something like: > > items: > > maximum: 40000 > > minimum: 160000 > >=20 > > Although, that would complain about the 5100 Ohms you're using. How come > > the example lies outside of the "typical" range? >=20 > Sorry to chime in here out of nowhere with this, but 2 things: No no, don't apologise - that's good info and makes sense. Thanks. > 1. Rfs for DS4402/4 has a different "typical" range than DS4424 (different > Vref and different output current range). > 2. "Typical" or "recommended" ranges should not translate to a hard limit= in > the driver. IMHO, no max or min value should be enforced here. --m6BRV1LwaCRhnwbk Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCaXpAmgAKCRB4tDGHoIJi 0mjLAP42bZ+VfG5ssTl5dKm/yhQ90F96Jm0tk+aXu3nH3zl9/wD/SvHoYPb9PnMC BRCG/zHPh2OhiMc1AYSKeIwdz0E4Zgk= =uaEK -----END PGP SIGNATURE----- --m6BRV1LwaCRhnwbk--