From 65925b65ed98ffdb277cf5ea1af45731dac0b30b Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Sat, 21 May 2016 20:43:16 +0200 Subject: iio: st_sensors: switch to a threaded interrupt commit 98ad8b41f58dff6b30713d7f09ae3834b8df7ded ("iio: st_sensors: verify interrupt event to status") caused a regression when reading ST sensors from a HRTimer trigger rather than the intrinsic interrupts: the HRTimer may trigger faster than the sensor provides new values, and as the check against new values available as a cause of the interrupt trigger was done in the poll function, this would bail out of the HRTimer interrupt with IRQ_NONE. So clearly we need to only check the new values available from the proper interrupt handler and not from the poll function, which should rather just read the raw values from the registers, put them into the buffer and be happy. To achieve this: switch the ST Sensors over to using a true threaded interrupt handler. In the interrupt thread, check if new values are available, else yield to the (potential) next device on the same interrupt line to check the registers. If the interrupt was ours, proceed to poll the values. Instead of relying on iio_trigger_generic_data_rdy_poll() as a top half to wake up the thread that polls the sensor for new data, have the thread call iio_trigger_poll_chained() after determining that is is the proper source of the interrupt. This is modelled on drivers/iio/accel/mma8452.c which is already using a properly threaded interrupt handler. In order to get the same precision in timestamps as previously, where samples would be timestamped in the poll function pf->timestamp when calling iio_trigger_generic_data_rdy_poll() we introduce a local timestamp in the sensor data, set it in the top half (fastpath) of the interrupt handler and provide that to the core when calling iio_push_to_buffers_with_timestamp(). Additionally: if the active scanmask is not set for the sensor no IRQs should be enabled and we need to bail out with IRQ_NONE. This can happen if spurious IRQs fire when installing the threaded interrupt handler. Tested with hard interrupt triggers on LIS331DL, then also tested with hrtimers on the same sensor by creating a 75Hz HRTimer and using it to poll the sensor. Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Cc: Giuseppe Barba <giuseppe.barba@st.com> Cc: Denis Ciocca <denis.ciocca@st.com> Reported-by: Crestez Dan Leonard <cdleonard@gmail.com> Tested-by: Crestez Dan Leonard <cdleonard@gmail.com> Tested-by: Jonathan Cameron <jic23@kernel.org> Fixes: 97865fe41322 ("iio: st_sensors: verify interrupt event to status") Signed-off-by: Jonathan Cameron <jic23@kernel.org> --- include/linux/iio/common/st_sensors.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/iio/common/st_sensors.h b/include/linux/iio/common/st_sensors.h index d029ffac0d69..99403b19092f 100644 --- a/include/linux/iio/common/st_sensors.h +++ b/include/linux/iio/common/st_sensors.h @@ -223,6 +223,8 @@ struct st_sensor_settings { * @get_irq_data_ready: Function to get the IRQ used for data ready signal. * @tf: Transfer function structure used by I/O operations. * @tb: Transfer buffers and mutex used by I/O operations. + * @hw_irq_trigger: if we're using the hardware interrupt on the sensor. + * @hw_timestamp: Latest timestamp from the interrupt handler, when in use. */ struct st_sensor_data { struct device *dev; @@ -247,6 +249,9 @@ struct st_sensor_data { const struct st_sensor_transfer_function *tf; struct st_sensor_transfer_buffer tb; + + bool hw_irq_trigger; + s64 hw_timestamp; }; #ifdef CONFIG_IIO_BUFFER @@ -260,7 +265,8 @@ int st_sensors_allocate_trigger(struct iio_dev *indio_dev, const struct iio_trigger_ops *trigger_ops); void st_sensors_deallocate_trigger(struct iio_dev *indio_dev); - +int st_sensors_validate_device(struct iio_trigger *trig, + struct iio_dev *indio_dev); #else static inline int st_sensors_allocate_trigger(struct iio_dev *indio_dev, const struct iio_trigger_ops *trigger_ops) @@ -271,6 +277,7 @@ static inline void st_sensors_deallocate_trigger(struct iio_dev *indio_dev) { return; } +#define st_sensors_validate_device NULL #endif int st_sensors_init_sensor(struct iio_dev *indio_dev, -- cgit v1.2.3