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From: Nikhil Gautam <nikhilgtr@gmail.com>
To: Jonathan Cameron <jic23@kernel.org>
Cc: "David Lechner" <dlechner@baylibre.com>,
	"Nuno Sá" <nuno.sa@analog.com>,
	"Andy Shevchenko" <andy@kernel.org>,
	"Stefan Windfeldt-Prytz" <stefan.windfeldt-prytz@axis.com>,
	linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Nikhil Gautam" <nikhilgtr@gmail.com>
Subject: [PATCH v1 1/4] iio: light: opt4001: Fix read-modify-write of wrong register in power down
Date: Mon, 13 Jul 2026 01:54:48 +0530	[thread overview]
Message-ID: <20260712202451.20822-2-nikhilgtr@gmail.com> (raw)
In-Reply-To: <20260712202451.20822-1-nikhilgtr@gmail.com>

opt4001_power_down() intends to clear the operating mode bits in the
CTRL register but reads OPT4001_DEVICE_ID instead of OPT4001_CTRL.
The device ID value with the mode bits masked out is then written to
CTRL, corrupting the conversion time and fault count configuration.

Read the CTRL register instead so only the operating mode bits are
cleared and the rest of the configuration is preserved.

Signed-off-by: Nikhil Gautam <nikhilgtr@gmail.com>
---
 drivers/iio/light/opt4001.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/light/opt4001.c b/drivers/iio/light/opt4001.c
index ba4eb82d9bc2..f2cf496cc243 100644
--- a/drivers/iio/light/opt4001.c
+++ b/drivers/iio/light/opt4001.c
@@ -228,7 +228,7 @@ static int opt4001_power_down(struct opt4001_chip *chip)
 	int ret;
 	unsigned int reg;
 
-	ret = regmap_read(chip->regmap, OPT4001_DEVICE_ID, &reg);
+	ret = regmap_read(chip->regmap, OPT4001_CTRL, &reg);
 	if (ret) {
 		dev_err(dev, "Failed to read configuration\n");
 		return ret;
-- 
2.39.5


  reply	other threads:[~2026-07-12 20:25 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-12 20:24 [PATCH 0/4] iio: light: opt4001: Fixes from code review Nikhil Gautam
2026-07-12 20:24 ` Nikhil Gautam [this message]
2026-07-13  0:42   ` [PATCH v1 1/4] iio: light: opt4001: Fix read-modify-write of wrong register in power down Jonathan Cameron
2026-07-13  3:33     ` Nikhil Gautam
2026-07-12 20:24 ` [PATCH v1 2/4] iio: light: opt4001: Fix incompatible pointer type passed to div_u64_rem() Nikhil Gautam
2026-07-13  0:43   ` Jonathan Cameron
2026-07-13  3:31     ` Nikhil Gautam
2026-07-12 20:24 ` [PATCH v1 3/4] iio: light: opt4001: Reject integration times with a non-zero seconds part Nikhil Gautam
2026-07-13  0:44   ` Jonathan Cameron
2026-07-12 20:24 ` [PATCH v1 4/4] iio: light: opt4001: Fix reversed GENMASK() arguments in fault count mask Nikhil Gautam
2026-07-13  0:45   ` Jonathan Cameron
2026-07-13 11:25   ` Andy Shevchenko

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