linux-kernel - [PATCH 4.19 36/96] iio: gyro: mpu3050: fix chip ID reading

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Message-Id: <20190424170922.335765869@linuxfoundation.org>
Date:   Wed, 24 Apr 2019 19:09:41 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Sergey Larin <cerg2010cerg2010@...l.ru>,
        Linus Walleij <linus.walleij@...aro.org>,
        Stable@...r.kernel.org,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>
Subject: [PATCH 4.19 36/96] iio: gyro: mpu3050: fix chip ID reading

From: Sergey Larin <cerg2010cerg2010@...l.ru>

commit 409a51e0a4a5f908763191fae2c29008632eb712 upstream.

According to the datasheet, the last bit of CHIP_ID register controls
I2C bus, and the first one is unused. Handle this correctly.

Note that there are chips out there that have a value such that
the id check currently fails.

Signed-off-by: Sergey Larin <cerg2010cerg2010@...l.ru>
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
Cc: <Stable@...r.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/iio/gyro/mpu3050-core.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/iio/gyro/mpu3050-core.c
+++ b/drivers/iio/gyro/mpu3050-core.c
@@ -29,7 +29,8 @@
 
 #include "mpu3050.h"
 
-#define MPU3050_CHIP_ID		0x69
+#define MPU3050_CHIP_ID		0x68
+#define MPU3050_CHIP_ID_MASK	0x7E
 
 /*
  * Register map: anything suffixed *_H is a big-endian high byte and always
@@ -1176,8 +1177,9 @@ int mpu3050_common_probe(struct device *
 		goto err_power_down;
 	}
 
-	if (val != MPU3050_CHIP_ID) {
-		dev_err(dev, "unsupported chip id %02x\n", (u8)val);
+	if ((val & MPU3050_CHIP_ID_MASK) != MPU3050_CHIP_ID) {
+		dev_err(dev, "unsupported chip id %02x\n",
+				(u8)(val & MPU3050_CHIP_ID_MASK));
 		ret = -ENODEV;
 		goto err_power_down;
 	}