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Tue, 11 Feb 2025 18:46:44 -0500 Received: from ASHBMBX8.ad.analog.com (10.64.17.5) by ASHBMBX8.ad.analog.com (10.64.17.5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.14; Tue, 11 Feb 2025 18:46:44 -0500 Received: from zeus.spd.analog.com (10.66.68.11) by ashbmbx8.ad.analog.com (10.64.17.5) with Microsoft SMTP Server id 15.2.986.14 via Frontend Transport; Tue, 11 Feb 2025 18:46:44 -0500 Received: from JSANTO12-L01.ad.analog.com ([10.65.60.206]) by zeus.spd.analog.com (8.15.1/8.15.1) with ESMTP id 51BNkXAl009863; Tue, 11 Feb 2025 18:46:35 -0500 From: Jonathan Santos To: , , CC: Jonathan Santos , , , , , , , , , Subject: [PATCH v3 02/17] iio: adc: ad7768-1: set MOSI idle state to prevent accidental reset Date: Tue, 11 Feb 2025 20:46:30 -0300 Message-ID: <20250211234630.1007989-1-Jonathan.Santos@analog.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ADIRuleOP-NewSCL: Rule Triggered X-Proofpoint-ORIG-GUID: MDcFvKKOP3YI3htj5VmP1Q1yAF9Cbep3 X-Proofpoint-GUID: MDcFvKKOP3YI3htj5VmP1Q1yAF9Cbep3 X-Authority-Analysis: v=2.4 cv=VPInn8PX c=1 sm=1 tr=0 ts=67abe165 cx=c_pps a=PpDZqlmH/M8setHirZLBMw==:117 a=PpDZqlmH/M8setHirZLBMw==:17 a=T2h4t0Lz3GQA:10 a=gAnH3GRIAAAA:8 a=x-s49S57KS4xq0-Af7kA:9 a=oVHKYsEdi7-vN-J5QA_j:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1057,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-02-11_10,2025-02-11_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 suspectscore=0 malwarescore=0 bulkscore=0 mlxscore=0 lowpriorityscore=0 priorityscore=1501 clxscore=1015 mlxlogscore=916 phishscore=0 adultscore=0 spamscore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2501170000 definitions=main-2502110158 Datasheet recommends Setting the MOSI idle state to high in order to prevent accidental reset of the device when SCLK is free running. This happens when the controller clocks out a 1 followed by 63 zeros while the CS is held low. Check if SPI controller supports SPI_MOSI_IDLE_HIGH flag and set it. Fixes: a5f8c7da3dbe ("iio: adc: Add AD7768-1 ADC basic support") Signed-off-by: Jonathan Santos --- v3 Changes: * Patch moved closer to start of the patch set. v2 Changes: * Only setup SPI_MOSI_IDLE_HIGH flag if the controller supports it, otherwise the driver continues the same. I realized that using bits_per_word does not avoid the problem that MOSI idle state is trying to solve. If the controller drives the MOSI low between bytes during a transfer, nothing happens. --- drivers/iio/adc/ad7768-1.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c index c3cf04311c40..2e2d50ccb744 100644 --- a/drivers/iio/adc/ad7768-1.c +++ b/drivers/iio/adc/ad7768-1.c @@ -574,6 +574,21 @@ static int ad7768_probe(struct spi_device *spi) return -ENOMEM; st = iio_priv(indio_dev); + /* + * Datasheet recommends SDI line to be kept high when data is not being + * clocked out of the controller and the spi clock is free running, + * to prevent accidental reset. + * Since many controllers do not support the SPI_MOSI_IDLE_HIGH flag + * yet, only request the MOSI idle state to enable if the controller + * supports it. + */ + if (spi->controller->mode_bits & SPI_MOSI_IDLE_HIGH) { + spi->mode |= SPI_MOSI_IDLE_HIGH; + ret = spi_setup(spi); + if (ret < 0) + return ret; + } + st->spi = spi; st->vref = devm_regulator_get(&spi->dev, "vref");