linux-kernel - [PATCH] media: i2c: imx296: Fix error handling while reading temperature

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Message-Id: <827f94730c85b742f9ae66209b383a50ca79ec43.1681683246.git.christophe.jaillet@wanadoo.fr>
Date:   Mon, 17 Apr 2023 00:14:42 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Manivannan Sadhasivam <mani@...nel.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        linux-media@...r.kernel.org
Subject: [PATCH] media: i2c: imx296: Fix error handling while reading temperature

If imx296_read() returns an error, its returned value is a negative value.
But because of the "& IMX296_TMDOUT_MASK" (i.e. 0x3ff), 'tmdout' can't be
negative.

So the error handling does not work as expected and a wrong value is used
to compute the temperature.

Apply the IMX296_TMDOUT_MASK mask after checking for errors to fix it.

Fixes: cb33db2b6ccf ("media: i2c: IMX296 camera sensor driver")
Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
 drivers/media/i2c/imx296.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/media/i2c/imx296.c b/drivers/media/i2c/imx296.c
index 4f22c0515ef8..c3d6d52fc772 100644
--- a/drivers/media/i2c/imx296.c
+++ b/drivers/media/i2c/imx296.c
@@ -922,10 +922,12 @@ static int imx296_read_temperature(struct imx296 *sensor, int *temp)
 	if (ret < 0)
 		return ret;
 
-	tmdout = imx296_read(sensor, IMX296_TMDOUT) & IMX296_TMDOUT_MASK;
+	tmdout = imx296_read(sensor, IMX296_TMDOUT);
 	if (tmdout < 0)
 		return tmdout;
 
+	tmdout &= IMX296_TMDOUT_MASK;
+
 	/* T(°C) = 246.312 - 0.304 * TMDOUT */;
 	*temp = 246312 - 304 * tmdout;
 
-- 
2.34.1