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From: Dimitri Fedrau <dima.fedrau@gmail.com>
Cc: Dimitri Fedrau <dima.fedrau@gmail.com>,
	Jonathan Cameron <jic23@kernel.org>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Andrew Hepp <andrew.hepp@ahepp.dev>,
	linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] iio: temperature: mcp9600: Fix temperature reading for negative values
Date: Wed, 24 Apr 2024 20:59:10 +0200	[thread overview]
Message-ID: <20240424185913.1177127-1-dima.fedrau@gmail.com> (raw)

Temperature is stored as 16bit value in two's complement format. Current
implementation ignores the sign bit. Make it aware of the sign bit by
using sign_extend32.

Fixes: 3f6b9598b6df ("iio: temperature: Add MCP9600 thermocouple EMF converter")
Signed-off-by: Dimitri Fedrau <dima.fedrau@gmail.com>
---
 drivers/iio/temperature/mcp9600.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/temperature/mcp9600.c b/drivers/iio/temperature/mcp9600.c
index 46845804292b..7a3eef5d5e75 100644
--- a/drivers/iio/temperature/mcp9600.c
+++ b/drivers/iio/temperature/mcp9600.c
@@ -52,7 +52,8 @@ static int mcp9600_read(struct mcp9600_data *data,
 
 	if (ret < 0)
 		return ret;
-	*val = ret;
+
+	*val = sign_extend32(ret, 15);
 
 	return 0;
 }
-- 
2.39.2


             reply	other threads:[~2024-04-24 18:59 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-24 18:59 Dimitri Fedrau [this message]
2024-04-27  8:49 ` [PATCH] iio: temperature: mcp9600: Fix temperature reading for negative values Marcelo Schmitt
2024-04-27 19:57   ` Dimitri Fedrau
2024-04-28 13:46     ` Jonathan Cameron
2024-04-28 18:46       ` Andrew Hepp
2024-04-29 19:44         ` Jonathan Cameron
2024-04-28 18:53       ` Marcelo Schmitt

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