From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from metis.whiteo.stw.pengutronix.de (metis.whiteo.stw.pengutronix.de [185.203.201.7]) (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 DEA07303A1D for ; Mon, 26 Jan 2026 09:54:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.203.201.7 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769421271; cv=none; b=nN1PkzBmOBJRpXIeMraMc7BT8Z6zV52TATPhwnA6TJBOrczFyDkefJPs45MdTUCDMpWwbhsaEJKUidvDtJNOr0hdBL2EcGrlMM80dghI7NTM2cNY0Bvlsm18Rvx3hVbIkrvrRPH0sdt+Gn1yw/eZaMTK5anKxWvzFzBmucGBplw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769421271; c=relaxed/simple; bh=XJgEyDrt9RXr9PCSjP5T5g9s+edYYN1rV7UfyY57nRU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=H329Tm5VT+3J2bp6Puj5YsemZRr1aPwc1WfZ3GBseV+dnoWfIRsNKoW58kvUGJdTwKTIoVm8ZEQXFrcipuC0voN1iyksXJIPM9syM5ka7NJCjBcYjE02BC5lHhGB6+ePvhgbXN/xaoeo8UJ3jGlLNCm1IHHqsdnp/Rrk8zyySEo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de; spf=pass smtp.mailfrom=pengutronix.de; arc=none smtp.client-ip=185.203.201.7 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=pengutronix.de Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1vkJIi-0003xn-8v; Mon, 26 Jan 2026 10:54:28 +0100 Received: from pty.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::c5]) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1vkJIi-002Yjr-0r; Mon, 26 Jan 2026 10:54:27 +0100 Received: from ore by pty.whiteo.stw.pengutronix.de with local (Exim 4.96) (envelope-from ) id 1vkJIh-00GVqU-1a; Mon, 26 Jan 2026 10:54:27 +0100 Date: Mon, 26 Jan 2026 10:54:27 +0100 From: Oleksij Rempel To: Jonathan Cameron Cc: Andy Shevchenko , Rob Herring , Conor Dooley , devicetree@vger.kernel.org, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Conor Dooley , Nuno =?utf-8?B?U8Oh?= , kernel@pengutronix.de, David Jander , Krzysztof Kozlowski , David Lechner Subject: Re: [PATCH v1 2/8] dt-bindings: iio: dac: maxim,ds4424: add maxim,rfs-ohms property Message-ID: References: <20260119182424.1660601-1-o.rempel@pengutronix.de> <20260119182424.1660601-3-o.rempel@pengutronix.de> <20260119-turbine-feminize-9dcd5c86feec@spud> <20260123092819.6ae81211@jic23-huawei> <20260125102207.37ce3501@jic23-huawei> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260125102207.37ce3501@jic23-huawei> X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-SA-Exim-Connect-IP: 2a0a:edc0:0:c01:1d::a2 X-SA-Exim-Mail-From: ore@pengutronix.de X-SA-Exim-Scanned: No (on metis.whiteo.stw.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: devicetree@vger.kernel.org On Sun, Jan 25, 2026 at 10:22:07AM +0000, Jonathan Cameron wrote: > On Fri, 23 Jan 2026 11:03:38 +0100 > Oleksij Rempel wrote: > > > On Fri, Jan 23, 2026 at 09:28:19AM +0000, Jonathan Cameron wrote: > > > On Mon, 19 Jan 2026 18:27:52 +0000 > > > Conor Dooley wrote: > > > > > > > On Mon, Jan 19, 2026 at 07:24:18PM +0100, Oleksij Rempel wrote: > > > > > Introduce the 'maxim,rfs-ohms' property. The full-scale output current > > > > > of these DACs is determined by external resistors (Rfs) connected to > > > > > the FS pins. The driver requires the physical resistance values to > > > > > calculate the correct current scale (Amps per step) for the IIO > > > > > subsystem. > > > > > > > > > > Keep it optional to avoid forcing updates of existing DTs; without it > > > > > the driver cannot derive a correct IIO scale. > > > > > > > > I don't really follow the logic here, if the driver doesn't work > > > > properly without it, shouldn't it be a required property even if that > > > > means existing devicetrees get new warnings? Warnings are preferable to > > > > the drivers malfunctioning on those devices, after all! > > > > > > Agreed. The driver can paper over holes or I guess we could provide a default > > > if the datasheet has some reference value or similar? > > > > No, this DAC controls the current. The current range is application specific and > > defined by the load resistors. Is it better to not provide scale if this > > information not available, guessing it will make things worse and > > potentially damage some HW. > > > Then does this need to be a fix on the driver side? > Or are you just suggesting not proving the scale if we don't have enough info? > That's fine if so. I suggest to not provide scale if we don't have enough info. It will be disabled in the driver if maxim,rfs-ohms is not provided in the DT. -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |