iio: hid-sensors: Use software trigger

Recent changes linux mainline resulted in warning:
"genirq: Warn about using IRQF_ONESHOT without a threaded handler"
when HID sensor hub is used.

When INDIO_BUFFER_TRIGGERED is used, the core attaches a poll function
when enabling the buffer. This poll function uses request_threaded_irq()
with both bottom half and top half handlers. But when using HID
sensor hub, bottom half (thread handler) is not registered.

In HID sensors, once a sensor is powered on, the hub collects samples
and pushes data to the host when programmed thresholds are met. When
this data is received for a sensor, it is pushed using
iio_push_to_buffers_with_ts().

The sensor is powered ON or OFF based on the trigger callback
set_trigger_state() when the poll function is attached. During the call
to iio_triggered_buffer_setup_ext(), the HID sensor specifies only a
handler function but provides no thread handler, as there is no data
to read from the hub in thread context. Internally, this results in
calling request_threaded_irq(). Recent kernel changes now warn when
request_threaded_irq() is called without a thread handler.

To address this issue, fundamental changes are required to avoid using
iio_triggered_buffer_setup_ext(). HID sensors can use
INDIO_BUFFER_SOFTWARE instead of INDIO_BUFFER_TRIGGERED, as this can
work in trigger-less mode.

In this approach, when user space opens the buffer, the sensor is powered
on, and when the buffer is closed, the sensor is powered off using
iio_buffer_setup_ops callbacks.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/common/hid-sensors/hid-sensor-trigger.c b/drivers/iio/common/hid-sensors/hid-sensor-trigger.c
index 5540e2d28f4acf358328229def0d511bc549931c..417c4ab8c1b27f7e4e155c48321686073d631d3a 100644 (file)
--- a/drivers/iio/common/hid-sensors/hid-sensor-trigger.c
+++ b/drivers/iio/common/hid-sensors/hid-sensor-trigger.c
@@ -14,6 +14,7 @@
 #include <linux/iio/triggered_buffer.h>
 #include <linux/iio/trigger_consumer.h>
 #include <linux/iio/sysfs.h>
+#include <linux/iio/kfifo_buf.h>
 #include "hid-sensor-trigger.h"
 
 static ssize_t _hid_sensor_set_report_latency(struct device *dev,
@@ -202,12 +203,21 @@ static void hid_sensor_set_power_work(struct work_struct *work)
                _hid_sensor_power_state(attrb, true);
 }
 
-static int hid_sensor_data_rdy_trigger_set_state(struct iio_trigger *trig,
-                                               bool state)
+static int buffer_postenable(struct iio_dev *indio_dev)
 {
-       return hid_sensor_power_state(iio_trigger_get_drvdata(trig), state);
+       return hid_sensor_power_state(iio_device_get_drvdata(indio_dev), 1);
 }
 
+static int buffer_predisable(struct iio_dev *indio_dev)
+{
+       return hid_sensor_power_state(iio_device_get_drvdata(indio_dev), 0);
+}
+
+static const struct iio_buffer_setup_ops hid_sensor_buffer_ops = {
+       .postenable = buffer_postenable,
+       .predisable = buffer_predisable,
+};
+
 void hid_sensor_remove_trigger(struct iio_dev *indio_dev,
                               struct hid_sensor_common *attrb)
 {
@@ -219,14 +229,9 @@ void hid_sensor_remove_trigger(struct iio_dev *indio_dev,
        cancel_work_sync(&attrb->work);
        iio_trigger_unregister(attrb->trigger);
        iio_trigger_free(attrb->trigger);
-       iio_triggered_buffer_cleanup(indio_dev);
 }
 EXPORT_SYMBOL_NS(hid_sensor_remove_trigger, "IIO_HID");
 
-static const struct iio_trigger_ops hid_sensor_trigger_ops = {
-       .set_trigger_state = &hid_sensor_data_rdy_trigger_set_state,
-};
-
 int hid_sensor_setup_trigger(struct iio_dev *indio_dev, const char *name,
                                struct hid_sensor_common *attrb)
 {
@@ -239,25 +244,34 @@ int hid_sensor_setup_trigger(struct iio_dev *indio_dev, const char *name,
        else
                fifo_attrs = NULL;
 
-       ret = iio_triggered_buffer_setup_ext(indio_dev,
-                                            &iio_pollfunc_store_time, NULL,
-                                            IIO_BUFFER_DIRECTION_IN,
-                                            NULL, fifo_attrs);
+       indio_dev->modes = INDIO_DIRECT_MODE | INDIO_HARDWARE_TRIGGERED;
+
+       ret = devm_iio_kfifo_buffer_setup_ext(&indio_dev->dev, indio_dev,
+                                             &hid_sensor_buffer_ops,
+                                             fifo_attrs);
        if (ret) {
-               dev_err(&indio_dev->dev, "Triggered Buffer Setup Failed\n");
+               dev_err(&indio_dev->dev, "Kfifo Buffer Setup Failed\n");
                return ret;
        }
 
+       /*
+        * The current user space in distro "iio-sensor-proxy" is not working in
+        * trigerless mode and it expects
+        * /sys/bus/iio/devices/iio:device0/trigger/current_trigger.
+        * The change replacing iio_triggered_buffer_setup_ext() with
+        * devm_iio_kfifo_buffer_setup_ext() will not create attribute without
+        * registering a trigger with INDIO_HARDWARE_TRIGGERED.
+        * So the below code fragment is still required.
+        */
+
        trig = iio_trigger_alloc(indio_dev->dev.parent,
                                 "%s-dev%d", name, iio_device_id(indio_dev));
        if (trig == NULL) {
                dev_err(&indio_dev->dev, "Trigger Allocate Failed\n");
-               ret = -ENOMEM;
-               goto error_triggered_buffer_cleanup;
+               return -ENOMEM;
        }
 
        iio_trigger_set_drvdata(trig, attrb);
-       trig->ops = &hid_sensor_trigger_ops;
        ret = iio_trigger_register(trig);
 
        if (ret) {
@@ -284,8 +298,6 @@ error_unreg_trigger:
        iio_trigger_unregister(trig);
 error_free_trig:
        iio_trigger_free(trig);
-error_triggered_buffer_cleanup:
-       iio_triggered_buffer_cleanup(indio_dev);
        return ret;
 }
 EXPORT_SYMBOL_NS(hid_sensor_setup_trigger, "IIO_HID");