From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f178.google.com (mail-pl1-f178.google.com [209.85.214.178]) (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 F20B7223322 for ; Fri, 1 May 2026 02:35:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.178 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777602944; cv=none; b=WiCBe594zSSMhOuSyGd4vqMW1z4evlhm2di9nqo1+kT+dyREIm5K6gLZNEOfQozpAkPI/MJJTsSgmxLk6ehEt4YYusqoPwImW1mkCmoigOcHdz5WU9m8Zk2IyhajAu1D8SxUCvgKYdoFDojHRRiKKriwm2ocIat2t7PH/yZ7k4Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777602944; c=relaxed/simple; bh=Aocggj3/ePT4e+jesYw7vvuMFmGQ27GviwPBpJeA378=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XdS/tTd/LMskY+F8r2t0mHxgdci/E88i1QFy8SJflVxIpt6p+fvbNeYriOviM+tggeUl6vTPvN3nbgG7kuZu3ir5Bryk/DzfIsf2zo/miTrSw9pfB1wVWhlFM8oJ9bQ2C3ndoBow2+9BVp6dZHbbGQhD1aCBBJeXWnrDXlUIzm8= 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=rAn1fXZH; arc=none smtp.client-ip=209.85.214.178 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="rAn1fXZH" Received: by mail-pl1-f178.google.com with SMTP id d9443c01a7336-2b7adb38d65so14255975ad.2 for ; Thu, 30 Apr 2026 19:35:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1777602942; x=1778207742; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=BSfAJ6VemJUOPmI4zNJhVr/AZDIzWGdUsU6uHQklRW0=; b=rAn1fXZHJD+cUUsNuJppNI0jtcY1SFSTZVyVBdvAFMZTgojUvRKFZXlBPLUNgOHGue yWgWeRPoXaAVzjyb37PHmz7AItj9wTOS/6ufQ64UmuiPrsKSJGwXyDyuJKRkqUc2tDEK OJdBX5PThwYjzCZnEduTwOOw9M/fr0xYv1DakaL0ixSTN0OwZyJV/quHTqlkpHsD8ZA6 gPIUCp3BDXPl0jYB6E5DiYPWtUrcVaP/xSdvOzlWnlgaUnYIueNVdN4M9Mvpas2+rdmA 8iQn/G8cdTFOWmEDGqECbOeoo5rscT1G3DrtQ3rkzzSMv7xZZ5UONycKyTBNmWpBiOIx efZw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1777602942; x=1778207742; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=BSfAJ6VemJUOPmI4zNJhVr/AZDIzWGdUsU6uHQklRW0=; b=BIQrKWtt873hj+5jkT3XjdtLT1lSMQ6X3NiggwcO3sNsESmVSNz135EcRy2J3jIN6H 4MHjCwH9/ffpZQcxikOnpz7AnZtcmMPMkMc5fZ/9Zne2xV9fGSor8c9/RXX6q9csVfaK YeNBH+cajwnsxSmV3yf6Gy81lFIyq04SyMPhQwN7dcuoVn2qWPF77NIvIMBCqs7L6JLg GU5oG7eItqsiuwOqzYqj1AePuEoaGNucsx59Wp/lsGh73pynrI8VwkFYknnzkYRGsftt 2uspGxp0Se61RYmlI/s3jwDTRSTTY2PizPS6jPr7dIJ65vW2NPWeUj1FDYR7ZTD52sKz eecw== X-Gm-Message-State: AOJu0Yx9x8lTzSOSmu7XNZFcxJgHaq2jD9JA4sSbvUNE7A92asPNNMV6 Ue+QGpe4cQdNODtTPpY56HkdC7GHAAJEQrdQSdrbiIalkM7GHXoTQsZw X-Gm-Gg: AeBDiesXvHOKbSj1jGcdp0N9l1Q222h4nTtc7QITvhXVR3AA9PNUlH0qlXx2vW4TNV0 KPxRyXaMgxBCcGQHlTB0zwPG2+OH+dV1qya7+fZihMH/BWdeeKq4x0fPZ/Uu87AVdQjl+mNlWb2 MKjJchXXbKbm3UjOhNptgUHwIp0u9H3BRzc3u8aAtDm6h41mTY7GBKVanFmlcaSi2InkPyTsWaK 55tCVdwiOyNt24Vs/UC5rJy0Y6J2/S3vMAVaJsfRrKNsY9Lj9SskCrhEwXrORpUaaw/iDcsrTik 4I89azyDl4i+r98LPI04A91qOhCZYeYJuuYbhlcVIW9Y3jtwGd7byQMS3vJ2GZdMUBgbaO2RpVs PRLM3sATVlif6b9FC2WBBRsMEb79O1otPrpW5b5VxuUalG1wcbeEkliwktp6E+NKiOTIOBtCNJU Ij5rKuPx/BPH+EsU/dQngnbfwXdyPzieKcCGCyjz2+lShCa0/rNOZOOmq8y+0UKihwxHT4wmfya VhfjBh52mrfEgnO X-Received: by 2002:a17:903:2ed0:b0:2b2:4a9a:b168 with SMTP id d9443c01a7336-2b9a23175c0mr57603095ad.11.1777602942231; Thu, 30 Apr 2026 19:35:42 -0700 (PDT) Received: from tabrez-VivoBook-ASUSLaptop-X513UA-KM513UA.. ([116.72.73.183]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b9caa7e791sm9341385ad.7.2026.04.30.19.35.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Apr 2026 19:35:41 -0700 (PDT) From: Tabrez Ahmed To: Guenter Roeck Cc: linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org, shuah@kernel.org, me@brighamcampbell.com, Tabrez Ahmed , Sashiko Subject: [PATCH v5 1/3] hwmon: (ads7871) Fix endianness bug in 16-bit register reads Date: Fri, 1 May 2026 08:05:28 +0530 Message-ID: <20260501023530.31160-2-tabreztalks@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260501023530.31160-1-tabreztalks@gmail.com> References: <20260501023530.31160-1-tabreztalks@gmail.com> Precedence: bulk X-Mailing-List: linux-hwmon@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The ads7871_read_reg16() function relies on spi_w8r16() to read the 16-bit sensor output. The ADS7871 device transmits the Least Significant Byte (LSB) first. On Little-Endian architectures, spi_w8r16() correctly reconstructs the 16-bit value. However, on Big-Endian architectures, the byte swapping causes the first received byte (LSB) to be placed in the most significant byte of the u16, resulting in corrupted voltage readings. Replace spi_w8r16() with a manual spi_write_then_read() into a byte array, and safely reconstruct the integer using get_unaligned_le16() to ensure correct behavior across all architectures. Additionally, use a u8 variable for the command byte to ensure the correct instruction is transmitted on Big-Endian systems. Reported-by: Sashiko Closes: https://sashiko.dev/#/patchset/20260418034601.90226-1-tabreztalks@gmail.com Signed-off-by: Tabrez Ahmed --- drivers/hwmon/ads7871.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/drivers/hwmon/ads7871.c b/drivers/hwmon/ads7871.c index 9bfdf9e6bcd77..d77eff430935b 100644 --- a/drivers/hwmon/ads7871.c +++ b/drivers/hwmon/ads7871.c @@ -59,9 +59,9 @@ #include #include #include +#include #define DEVICE_NAME "ads7871" - struct ads7871_data { struct spi_device *spi; }; @@ -77,9 +77,17 @@ static int ads7871_read_reg8(struct spi_device *spi, int reg) static int ads7871_read_reg16(struct spi_device *spi, int reg) { int ret; + u8 tx_cmd; + u8 rx_buf[2]; + reg = reg | INST_READ_BM | INST_16BIT_BM; - ret = spi_w8r16(spi, reg); - return ret; + tx_cmd = reg; + + ret = spi_write_then_read(spi, &tx_cmd, 1, rx_buf, 2); + if (ret < 0) + return ret; + + return get_unaligned_le16(rx_buf); } static int ads7871_write_reg8(struct spi_device *spi, int reg, u8 val) -- 2.43.0