The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 3a63da26db0a864134f023f088d41deacd509997 Mon Sep 17 00:00:00 2001

From: Lorenzo Bianconi lorenzo@kernel.org Date: Fri, 13 Mar 2020 19:06:00 +0100 Subject: [PATCH] iio: imu: st_lsm6dsx: flush hw FIFO before resetting the device

flush hw FIFO before device reset in order to avoid possible races on interrupt line 1. If the first interrupt line is asserted during hw reset the device will work in I3C-only mode (if it is supported)

Fixes: 801a6e0af0c6 ("iio: imu: st_lsm6dsx: add support to LSM6DSO") Fixes: 43901008fde0 ("iio: imu: st_lsm6dsx: add support to LSM6DSR") Reported-by: Mario Tesi mario.tesi@st.com Signed-off-by: Lorenzo Bianconi lorenzo@kernel.org Reviewed-by: Vitor Soares vitor.soares@synopsys.com Tested-by: Vitor Soares vitor.soares@synopsys.com Cc: Stable@vger.kernel.org Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com

diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c index 84d219ae6aee..4426524b59f2 100644 --- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c @@ -2036,11 +2036,21 @@ static int st_lsm6dsx_init_hw_timer(struct st_lsm6dsx_hw *hw) return 0; }

-static int st_lsm6dsx_init_device(struct st_lsm6dsx_hw *hw) +static int st_lsm6dsx_reset_device(struct st_lsm6dsx_hw *hw) { const struct st_lsm6dsx_reg *reg; int err;

+ /* + * flush hw FIFO before device reset in order to avoid + * possible races on interrupt line 1. If the first interrupt + * line is asserted during hw reset the device will work in + * I3C-only mode (if it is supported) + */ + err = st_lsm6dsx_flush_fifo(hw); + if (err < 0 && err != -ENOTSUPP) + return err; + /* device sw reset */ reg = &hw->settings->reset; err = regmap_update_bits(hw->regmap, reg->addr, reg->mask, @@ -2059,6 +2069,18 @@ static int st_lsm6dsx_init_device(struct st_lsm6dsx_hw *hw)

msleep(50);

+ return 0; +} + +static int st_lsm6dsx_init_device(struct st_lsm6dsx_hw *hw) +{ + const struct st_lsm6dsx_reg *reg; + int err; + + err = st_lsm6dsx_reset_device(hw); + if (err < 0) + return err; + /* enable Block Data Update */ reg = &hw->settings->bdu; err = regmap_update_bits(hw->regmap, reg->addr, reg->mask,