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Sun, 06 Sep 2026 04:42:46 -0700 (PDT) From: Abdelnasser Hussein To: gregkh@linuxfoundation.org, jic23@kernel.org, nuno.sa@analog.com, Michael.Hennerich@analog.com Cc: dlechner@baylibre.com, andy@kernel.org, linux@analog.com, linux-iio@vger.kernel.org, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org, Abdelnasser Hussein Subject: [PATCH v4 1/2] staging: iio: adc: ad7816: Serialize SPI read operations Date: Sun, 6 Sep 2026 14:40:48 +0300 Message-ID: <20260906114049.32912-2-abdelnasserhussein11@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260906114049.32912-1-abdelnasserhussein11@gmail.com> References: <20260906114049.32912-1-abdelnasserhussein11@gmail.com> 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 Content-Type: text/plain; charset="utf-8" Add a mutex to serialize SPI read operations and prevent data corruption. U= sed guard(mutex) and devm_mutex_init() for safer and automatic cleanup. Signed-off-by: Abdelnasser Hussein --- drivers/staging/iio/adc/ad7816.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/staging/iio/adc/ad7816.c b/drivers/staging/iio/adc/ad7= 816.c index 0e32a2295990..ab80b3a889bb 100644 --- a/drivers/staging/iio/adc/ad7816.c +++ b/drivers/staging/iio/adc/ad7816.c @@ -14,6 +14,8 @@ #include #include #include +#include +#include =20 #include #include @@ -65,7 +67,8 @@ static int ad7816_spi_read(struct ad7816_chip_info *chip,= u16 *data) { struct spi_device *spi_dev =3D chip->spi_dev; int ret; - __be16 buf; + + guard(mutex)(&chip->lock); =20 gpiod_set_value(chip->rdwr_pin, 1); gpiod_set_value(chip->rdwr_pin, 0); @@ -360,6 +363,10 @@ static int ad7816_probe(struct spi_device *spi_dev) return -ENOMEM; chip =3D iio_priv(indio_dev); =20 + ret =3D devm_mutex_init(&spi_dev->dev, &chip->lock); + if (ret) + return ret; + chip->spi_dev =3D spi_dev; for (i =3D 0; i <=3D AD7816_CS_MAX; i++) chip->oti_data[i] =3D 203; --=20 2.54.0 From nobody Sat Sep 26 01:04:59 2026 Received: from mail-wm1-f47.google.com (mail-wm1-f47.google.com [209.85.128.47]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 81D0538236E for ; 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Sun, 06 Sep 2026 04:43:13 -0700 (PDT) Received: from fedora ([154.182.82.204]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4858ab73c2bsm19356223f8f.22.2026.09.06.04.43.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 06 Sep 2026 04:43:13 -0700 (PDT) From: Abdelnasser Hussein To: gregkh@linuxfoundation.org, jic23@kernel.org, nuno.sa@analog.com, Michael.Hennerich@analog.com Cc: dlechner@baylibre.com, andy@kernel.org, linux@analog.com, linux-iio@vger.kernel.org, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org, Abdelnasser Hussein Subject: [PATCH v4 2/2] staging: iio: adc: ad7816: Use DMA-safe buffer for SPI read Date: Sun, 6 Sep 2026 14:40:49 +0300 Message-ID: <20260906114049.32912-3-abdelnasserhussein11@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260906114049.32912-1-abdelnasserhussein11@gmail.com> References: <20260906114049.32912-1-abdelnasserhussein11@gmail.com> 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 Content-Type: text/plain; charset="utf-8" Stack buffers are not guaranteed to be cache-coherent and must not be used with SPI reads, which can trigger issues with VMAP_STACK. Fix this by using a dedicated DMA-safe rx_buf aligned with IIO_DMA_MINALIGN. Also, correct the sizeof() argument from *data to chip->rx_buf to match the buffer size. Fixes: 7024425db64a ("staging: iio: adc: new driver for AD7816 devices") Signed-off-by: Abdelnasser Hussein --- drivers/staging/iio/adc/ad7816.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/staging/iio/adc/ad7816.c b/drivers/staging/iio/adc/ad7= 816.c index ab80b3a889bb..e14ae805f076 100644 --- a/drivers/staging/iio/adc/ad7816.c +++ b/drivers/staging/iio/adc/ad7816.c @@ -52,6 +52,8 @@ struct ad7816_chip_info { u8 oti_data[AD7816_CS_MAX + 1]; u8 channel_id; /* 0 always be temperature */ u8 mode; + struct mutex lock; /* protect device state during SPI transfers */ + __be16 rx_buf __aligned(IIO_DMA_MINALIGN); }; =20 enum ad7816_type { @@ -94,13 +96,13 @@ static int ad7816_spi_read(struct ad7816_chip_info *chi= p, u16 *data) =20 gpiod_set_value(chip->rdwr_pin, 0); gpiod_set_value(chip->rdwr_pin, 1); - ret =3D spi_read(spi_dev, &buf, sizeof(*data)); + ret =3D spi_read(spi_dev, &chip->rx_buf, sizeof(chip->rx_buf)); if (ret < 0) { dev_err(&spi_dev->dev, "SPI data read error\n"); return ret; } =20 - *data =3D be16_to_cpu(buf); + *data =3D be16_to_cpu(chip->rx_buf); =20 return ret; } --=20 2.54.0