This is a note to let you know that I've just added the patch titled
iio: bmg160: reset chip when probing
to my staging git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From 4bdc9029685ac03be50b320b29691766d2326c2b Mon Sep 17 00:00:00 2001
From: Quentin Schulz <quentin.schulz@xxxxxxxxxxxxxxxxxx>
Date: Tue, 21 Mar 2017 16:52:14 +0100
Subject: iio: bmg160: reset chip when probing
The gyroscope chip might need to be reset to be used.
Without the chip being reset, the driver stopped at the first
regmap_read (to get the CHIP_ID) and failed to probe.
The datasheet of the gyroscope says that a minimum wait of 30ms after
the reset has to be done.
This patch has been checked on a BMX055 and the datasheet of the BMG160
and the BMI055 give the same reset register and bits.
Signed-off-by: Quentin Schulz <quentin.schulz@xxxxxxxxxxxxxxxxxx>
Cc: <Stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jonathan Cameron <jic23@xxxxxxxxxx>
---
drivers/iio/gyro/bmg160_core.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/drivers/iio/gyro/bmg160_core.c b/drivers/iio/gyro/bmg160_core.c
index f7fcfa886f72..821919dd245b 100644
--- a/drivers/iio/gyro/bmg160_core.c
+++ b/drivers/iio/gyro/bmg160_core.c
@@ -27,6 +27,7 @@
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/regmap.h>
+#include <linux/delay.h>
#include "bmg160.h"
#define BMG160_IRQ_NAME "bmg160_event"
@@ -52,6 +53,9 @@
#define BMG160_DEF_BW 100
#define BMG160_REG_PMU_BW_RES BIT(7)
+#define BMG160_GYRO_REG_RESET 0x14
+#define BMG160_GYRO_RESET_VAL 0xb6
+
#define BMG160_REG_INT_MAP_0 0x17
#define BMG160_INT_MAP_0_BIT_ANY BIT(1)
@@ -236,6 +240,14 @@ static int bmg160_chip_init(struct bmg160_data *data)
int ret;
unsigned int val;
+ /*
+ * Reset chip to get it in a known good state. A delay of 30ms after
+ * reset is required according to the datasheet.
+ */
+ regmap_write(data->regmap, BMG160_GYRO_REG_RESET,
+ BMG160_GYRO_RESET_VAL);
+ usleep_range(30000, 30700);
+
ret = regmap_read(data->regmap, BMG160_REG_CHIP_ID, &val);
if (ret < 0) {
dev_err(dev, "Error reading reg_chip_id\n");
--
2.12.1