From nobody Tue Feb 10 03:37:39 2026 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 5752A36CDE8 for ; Mon, 19 Jan 2026 18:24:33 +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=1768847077; cv=none; b=DmzMdTq5VAUsihASWqx1Cq4HBgbW9rjF+haq38P3u+UaABN4qUZTeN7cF1fzvfcW6SURPh8aOAUY3SIrWH4WjnWrLAlY7CSpuJ+puBRDhApg09xdN/rU5n1ZsGofnIzPo84+QtsnkUATi+OLn8I/xoROZVfxtpNIu8w7X0WQZGE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768847077; c=relaxed/simple; bh=gKdxgCeUIfsMv9ke4Upzqo22FIpf6SCbXM4wJZi9nto=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mEDbyX65moYMs38sSABU6hMMIIGqrwzFldB7HxPxU93BuJAKPgZne1njO1GFPxCwmki0JdJB/XGNj6ZGca5qFakHuuIC5eZChBc1Myq2mdAEkiKtSiCsuYByJZrUA+zBsihNgiq2drAmdwY9subiwzYrhJgom5aINSLC2i6OKss= 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 1vhtvO-0004SS-7c; Mon, 19 Jan 2026 19:24:26 +0100 Received: from dude04.red.stw.pengutronix.de ([2a0a:edc0:0:1101:1d::ac] helo=dude04) 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 1vhtvO-001SUr-1Y; Mon, 19 Jan 2026 19:24:25 +0100 Received: from ore by dude04 with local (Exim 4.98.2) (envelope-from ) id 1vhtvN-00000006y2f-2wCL; Mon, 19 Jan 2026 19:24:25 +0100 From: Oleksij Rempel To: Jonathan Cameron , Rob Herring , Krzysztof Kozlowski , Conor Dooley Cc: Oleksij Rempel , kernel@pengutronix.de, linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, devicetree@vger.kernel.org, Andy Shevchenko , David Lechner , =?UTF-8?q?Nuno=20S=C3=A1?= , David Jander Subject: [PATCH v1 8/8] iio: dac: ds4424: document output sign and probe verification Date: Mon, 19 Jan 2026 19:24:24 +0100 Message-ID: <20260119182424.1660601-9-o.rempel@pengutronix.de> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260119182424.1660601-1-o.rempel@pengutronix.de> References: <20260119182424.1660601-1-o.rempel@pengutronix.de> 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 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: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Document that a zero output value is encoded with a don't-care sign bit and that the driver verifies device presence via a readable register since the hardware provides no device ID. Signed-off-by: Oleksij Rempel --- drivers/iio/dac/ds4424.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/iio/dac/ds4424.c b/drivers/iio/dac/ds4424.c index 13acb427d43b..2ccac674878e 100644 --- a/drivers/iio/dac/ds4424.c +++ b/drivers/iio/dac/ds4424.c @@ -194,6 +194,7 @@ static int ds4424_write_raw(struct iio_dev *indio_dev, if (val < -max_val || val > max_val) return -EINVAL; =20 + /* Canonicalize 0 to sink; datasheet treats sign as don't-care. */ if (val > 0) { raw.source_bit =3D DS4424_SOURCE_I; raw.dx =3D val; @@ -213,6 +214,7 @@ static int ds4424_verify_chip(struct iio_dev *indio_dev) { int ret, val; =20 + /* No device ID; verify presence by a readable register. */ ret =3D ds4424_get_value(indio_dev, &val, 0); if (ret < 0) dev_err(&indio_dev->dev, --=20 2.47.3