On PREEMPT_RT enabled kernels unmarked hrtimers are moved into soft
interrupt expiry mode by default.
The IIO hrtimer-trigger needs to run in hard interrupt context since it
will end up calling generic_handle_irq() which has the requirement to run
in hard interrupt context.
Explicitly specify that the timer needs to run in hard interrupt context by
using the HRTIMER_MODE_REL_HARD flag.
Fixes: f5c2f0215e36 ("hrtimer: Move unmarked hrtimers to soft interrupt expiry on RT")
Reported-by: Christian Eggers <ceggers@xxxxxxx>
Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
---
Changes since v1:
* Also pass HRTIMER_MODE_REL_HARD to hrtimer_start().
---
drivers/iio/trigger/iio-trig-hrtimer.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/iio/trigger/iio-trig-hrtimer.c b/drivers/iio/trigger/iio-trig-hrtimer.c
index f59bf8d58586..410de837d041 100644
--- a/drivers/iio/trigger/iio-trig-hrtimer.c
+++ b/drivers/iio/trigger/iio-trig-hrtimer.c
@@ -102,7 +102,7 @@ static int iio_trig_hrtimer_set_state(struct iio_trigger *trig, bool state)
if (state)
hrtimer_start(&trig_info->timer, trig_info->period,
- HRTIMER_MODE_REL);
+ HRTIMER_MODE_REL_HARD);
else
hrtimer_cancel(&trig_info->timer);
@@ -132,7 +132,7 @@ static struct iio_sw_trigger *iio_trig_hrtimer_probe(const char *name)
trig_info->swt.trigger->ops = &iio_hrtimer_trigger_ops;
trig_info->swt.trigger->dev.groups = iio_hrtimer_attr_groups;
- hrtimer_init(&trig_info->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ hrtimer_init(&trig_info->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
trig_info->timer.function = iio_hrtimer_trig_handler;
trig_info->sampling_frequency = HRTIMER_DEFAULT_SAMPLING_FREQUENCY;
--
2.20.1
