From nobody Tue Feb 10 07:21:17 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 5663A36A016 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=1768847078; cv=none; b=Ko3cpRPZ5DyoX6LtptGF0e+SU3j62MBnvaD7H0po59MWR8rxt8VzKxFYyIaQdFZDCG+b/1VV4DqUNCR+rq9hP3gldheMaSnEOLpPykjbEis+4yTaDC1gkf2uQL+riZxN4h1HMo4C1oF5Jli3ZkKrq5HLLJbJR6VpT9ewDcTkkvE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768847078; c=relaxed/simple; bh=+L8hofjKyjTSzyKgvlJ00wSPTK1EZoc14n6gT4ZKxvI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aBIyc1ulwfrxW9HSGCYnyOf6VCMJIjvijyz3s3zTsRWFcEC3f/NgRcGtMu7NOX15dQAJzW0sNNErBhHlSwWDuEWbaTGdIFGlcUnInyxkOdxyJ7bn5sJJ/O9DRIu7Xvm7TCgUltvlrBU/n9MBPuhGNLorNI55dKay1TzDESdknkI= 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-0004SO-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-001SUi-1B; Mon, 19 Jan 2026 19:24:25 +0100 Received: from ore by dude04 with local (Exim 4.98.2) (envelope-from ) id 1vhtvN-00000006y1y-2aWd; Mon, 19 Jan 2026 19:24:25 +0100 From: Oleksij Rempel To: Jonathan Cameron , Rob Herring , Krzysztof Kozlowski , Conor Dooley Cc: Oleksij Rempel , stable@vger.kernel.org, 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 4/8] iio: dac: ds4424: reject -128 RAW value Date: Mon, 19 Jan 2026 19:24:20 +0100 Message-ID: <20260119182424.1660601-5-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" The DS442x DAC uses sign-magnitude encoding, so -128 cannot be represented in hardware. With the previous check, userspace could pass -128, which gets converted to a magnitude of 128 and then truncated by the 7-bit DAC field. This ends up programming a zero magnitude with the sign bit set, i.e. an unintended output (effectively 0 mA instead of -128 steps). Reject -128 to avoid silently producing the wrong current. Fixes: d632a2bd8ffc ("iio: dac: ds4422/ds4424 dac driver") Cc: Signed-off-by: Oleksij Rempel --- drivers/iio/dac/ds4424.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/iio/dac/ds4424.c b/drivers/iio/dac/ds4424.c index 072b7e6672cf..9c24c37d3c42 100644 --- a/drivers/iio/dac/ds4424.c +++ b/drivers/iio/dac/ds4424.c @@ -143,7 +143,7 @@ static int ds4424_write_raw(struct iio_dev *indio_dev, =20 switch (mask) { case IIO_CHAN_INFO_RAW: - if (val < S8_MIN || val > S8_MAX) + if (val <=3D S8_MIN || val > S8_MAX) return -EINVAL; =20 if (val > 0) { --=20 2.47.3