On 21/03/17 15:52, Quentin Schulz wrote:
> 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>
Applied to the fixes-togreg branch of iio.git and marked for stable.
Thanks,
Jonathan
> ---
> 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 f7fcfa8..821919d 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");
>
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