From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-dy1-f195.google.com (mail-dy1-f195.google.com [74.125.82.195]) (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 A6AC12F8E8E for ; Sun, 10 May 2026 07:29:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.195 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778398183; cv=none; b=CyAgM0+SEhJ8tGfin2x3/51TQgTTHWNb546ePlh0e7PDTQH8aq7laZpZ07RN7jDclu8oiTrm+H0U4L3iiONCR3uL4oH9Pn7WQbza6eZDcGQexq8t2iZWGlZxAcITPN4sYqtJv+T3EI6SK7T65zFABS4IsRnJucuSxuS6Jfwu0i4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778398183; c=relaxed/simple; bh=qWCmPhOrDnUxqUKogWTLDFIt9grLd2AwEu1Rc3nJqfw=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=RA2TdqGDTp3LEPXu/MsWDwNe6oBcyI5DjoxOK1zFHyDvx/LQIjcNpwJSN/Sb+EQSEFkMQSXjmMeEz8tiEKjUL+hcSRlSAs22mzFXl8IIC0mW2EePm5prxibTbWRiyCnAWclIMdGBQhpMOaBMZoXq8C8lsd+uI2xVBDsTLZV/uic= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=EtWpE/2h; arc=none smtp.client-ip=74.125.82.195 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="EtWpE/2h" Received: by mail-dy1-f195.google.com with SMTP id 5a478bee46e88-2c156c4a9efso4363259eec.1 for ; Sun, 10 May 2026 00:29:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1778398182; x=1779002982; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=hAJj9gR9YqXW3Aa8yL22LCa/R0RncrwiTc1yi2jGMAM=; b=EtWpE/2hzHH7TmDXEoL/UblqPWLEuoboSleiqC3O05tG+8FXdrHHhlCPNEI/sB8bRi m/IGBEaOtCmv9CvLzsQjI8gRT9YdVTFzY4afxJy2K5QA6rCAFhU/McN4pGRB9B91X9Q7 7GKIqVKFwn3W1sae10rFgDl8vamRm+qU22PT9auhtXrREw0vBrZ0nOZfPc6olbS1IXBa LUnm2UXRzpxa+XKZo65hjNGQPbSraC5v7XygQCwl8jikzN3duFP4d5z65VUBaI2fxmem agw0QEqmt1RGNTHRzsqZ9grio+VxKS2l7KTpMsWyjHIcchLJTZHAG4gIjXN+RNKkW3Bw LRmA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1778398182; x=1779002982; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=hAJj9gR9YqXW3Aa8yL22LCa/R0RncrwiTc1yi2jGMAM=; b=qb2HPZE3SGVnCtn+Ar8DJ08JffebBNJRM/YwTUXoHr+GyrJKdq2qfVVpluacviB2dS Uy2LmHRh+A172zg9mguLTpU2ZZGXxHktfJf4wRiEL7H/0g1+gTAW3dpWhrH6WfrLtkme bErhjsOMCdHh1npn6CJThn0k20479FqeRWVf1b87hRETZLh5SES2gX00WCGlySrGFTxX 0yBXmJ5eI6Wn4fQGvwg9MUQz5fPicMnrUnoOgeuG33YcTEBUvHxYXv2nLF6gv+L3rYuC AtD5v1ifcU2B6+y1zr2E26TLJpNSn+KYJbuZ5C1KKbbVJ50I/xYLUf62k1icczuyPSXd +HAA== X-Forwarded-Encrypted: i=1; AFNElJ9kLcOtp6UMcycr/yX/5FDmn5wHbjQhpR+l9Jo6y2WHRNrO7/jhZIbXUoy2NHSLbdVjNr9VNo4/TcDZjHI=@vger.kernel.org X-Gm-Message-State: AOJu0Yyzqoz/lB8nyoU7k58rdI/dtwg/cq5Hyv6a3zCeo+FqWslBe64z ZRne0QmSdJQqu9WWhhjzbwtTEQJ9OnKXhSg0oya1mcgaGh7St9NnjRrq X-Gm-Gg: Acq92OExddfZK4shN6/2BSduFRCnyAXV1bFsbeq391TiWD5f2fCrX5G31iX3qp6pnO7 NuAMoruivBRzN1p4PFYeIqUIsOrqzYrXkHpxb+qwfaYOO0/43Jrcf3yoe6plBDzCctO06X9hVqu zVEL++tJGPDGeaZnC9PBnu5lGr3trHbHXfNe60XIF8hjbXz5Jfwc21jJD9MYZ5iOWJgZZXWnFYR dzsGHWe7GkdLUDP5u3X+PGAXsotfwcdVMHg7vc6EjzRDzog637RUtYD9Zz5Scw7KALNIXfwjNSg nD5dsxeslcXc5Kd23veA+7n3z59S9QJIStoltjBKTjyb3gJkkwCoMq46BCY3nFOSJ6M6eu8gq6P WIjwqMyHsJpydFGSppMsMgmYi8Ixs/rQmIzF+FE1MEFFpzpD0ZYeIJ3DhddVuUjoccCEnbtIauP rJU4HLGyn6bb2o2ShHmj6fQ+YdWbbU2JZPQ/WIJevEFzh0IocD9YKVDog= X-Received: by 2002:a05:7022:688c:b0:130:c9dc:bc55 with SMTP id a92af1059eb24-1319cf5d736mr10234387c88.28.1778398181601; Sun, 10 May 2026 00:29:41 -0700 (PDT) Received: from localhost.localdomain ([76.32.119.210]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-13277bb2b14sm11920107c88.0.2026.05.10.00.29.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 10 May 2026 00:29:41 -0700 (PDT) From: Hungyu Lin To: lars@metafoo.de, Michael.Hennerich@analog.com, jic23@kernel.org, gregkh@linuxfoundation.org Cc: dlechner@baylibre.com, nuno.sa@analog.com, andy@kernel.org, linux-iio@vger.kernel.org, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org, Hungyu Lin Subject: [PATCH] staging: iio: addac: adt7316: document SPI interface switching sequence Date: Sun, 10 May 2026 07:29:18 +0000 Message-Id: <20260510072918.85734-1-dennylin0707@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The device powers up in I2C mode. Switching to SPI mode requires sending a sequence of SPI writes as described in the datasheet. During this sequence, the device may still be in I2C mode, so SPI transactions may not be recognized and can fail. Such errors are expected and are ignored. Add a comment to clarify this behavior. Signed-off-by: Hungyu Lin --- drivers/staging/iio/addac/adt7316-spi.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/staging/iio/addac/adt7316-spi.c b/drivers/staging/iio/addac/adt7316-spi.c index f91325d11394..6d710e1d4aaa 100644 --- a/drivers/staging/iio/addac/adt7316-spi.c +++ b/drivers/staging/iio/addac/adt7316-spi.c @@ -106,7 +106,15 @@ static int adt7316_spi_probe(struct spi_device *spi_dev) return -EINVAL; } - /* switch from default I2C protocol to SPI protocol */ + /* + * The device powers up in I2C mode. Switching to SPI mode + * requires sending a sequence of SPI writes as described in + * the datasheet. + * + * During this sequence, the device may still be in I2C mode, + * so SPI transactions may not be recognized and can fail. + * Such errors are expected and are ignored. + */ adt7316_spi_write(spi_dev, 0, 0); adt7316_spi_write(spi_dev, 0, 0); adt7316_spi_write(spi_dev, 0, 0); -- 2.34.1