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iio: imu: st_lsm6dsx: fix edge-trigger interrupts 

commit 3f9bce7a22 upstream

If we are using edge IRQs, new samples can arrive while processing
current interrupt since there are no hw guarantees the irq line
stays "low" long enough to properly detect the new interrupt.
In this case the new sample will be missed.
Polling FIFO status register in st_lsm6dsx_handler_thread routine
allow us to read new samples even if the interrupt arrives while
processing previous data and the timeslot where the line is "low"
is too short to be properly detected.

Fixes: 89ca88a7cd ("iio: imu: st_lsm6dsx: support active-low interrupts")
Fixes: 290a6ce11d ("iio: imu: add support to lsm6dsx driver")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/5e93cda7dc1e665f5685c53ad8e9ea71dbae782d.1605378871.git.lorenzo@kernel.org
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
[sudip: manual backport to old irq handler path]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
Lorenzo Bianconi 2020-11-14 19:39:05 +01:00 committed by Greg Kroah-Hartman
parent 87ea51c902
commit 6f367fb1b7
1 changed files with 21 additions and 5 deletions
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26
drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
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@ -664,13 +664,29 @@ static irqreturn_t st_lsm6dsx_handler_irq(int irq, void *private)
static irqreturn_t st_lsm6dsx_handler_thread(int irq, void *private)
{
struct st_lsm6dsx_hw *hw = private;
int count;
int fifo_len = 0, len;
mutex_lock(&hw->fifo_lock);
count = hw->settings->fifo_ops.read_fifo(hw);
mutex_unlock(&hw->fifo_lock);
/*
* If we are using edge IRQs, new samples can arrive while
* processing current interrupt since there are no hw
* guarantees the irq line stays "low" long enough to properly
* detect the new interrupt. In this case the new sample will
* be missed.
* Polling FIFO status register allow us to read new
* samples even if the interrupt arrives while processing
* previous data and the timeslot where the line is "low" is
* too short to be properly detected.
*/
do {
mutex_lock(&hw->fifo_lock);
len = hw->settings->fifo_ops.read_fifo(hw);
mutex_unlock(&hw->fifo_lock);
return count ? IRQ_HANDLED : IRQ_NONE;
if (len > 0)
fifo_len += len;
} while (len > 0);
return fifo_len ? IRQ_HANDLED : IRQ_NONE;
}
static int st_lsm6dsx_buffer_preenable(struct iio_dev *iio_dev)