[PATCH 5.9 212/252] iio: imu: st_lsm6dsx: set 10ms as min shub slave timeout

Greg Kroah-Hartman
2020-11-23T12:59:03Z

From: Lorenzo Bianconi <lorenzo@kernel.org>

commit fe0b980ffd1dd8b10c09f82385514819ba2a661d upstream.

Set 10ms as minimum i2c slave configuration timeout since st_lsm6dsx
relies on accel ODR for i2c master clock and at high sample rates
(e.g. 833Hz or 416Hz) the slave sensor occasionally may need more cycles
than i2c master timeout (2s/833Hz + 1 ~ 3ms) to apply the configuration
resulting in an uncomplete slave configuration and a constant reading
from the i2c slave connected to st_lsm6dsx i2c master.

Fixes: 8f9a5249e3d9 ("iio: imu: st_lsm6dsx: enable 833Hz sample frequency for tagged sensors")
Fixes: c91c1c844ebd ("iio: imu: st_lsm6dsx: add i2c embedded controller support")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Cc: <Stable@vger.kernel.org>
Link: https://lore.kernel.org/r/a69c8236bf16a1569966815ed71710af2722ed7d.1604247274.git.lorenzo@kernel.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c
@@ -156,11 +156,13 @@ static const struct st_lsm6dsx_ext_dev_s
static void st_lsm6dsx_shub_wait_complete(struct st_lsm6dsx_hw *hw)
{
struct st_lsm6dsx_sensor *sensor;
- u32 odr;
+ u32 odr, timeout;

sensor = iio_priv(hw->iio_devs[ST_LSM6DSX_ID_ACC]);
odr = (hw->enable_mask & BIT(ST_LSM6DSX_ID_ACC)) ? sensor->odr : 12500;
- msleep((2000000U / odr) + 1);
+ /* set 10ms as minimum timeout for i2c slave configuration */
+ timeout = max_t(u32, 2000000U / odr + 1, 10);
+ msleep(timeout);
}

/*