Re: [PATCH v1] HID: hid-sensor-hub: Extend API for async reads

On Sun, 2015-02-01 at 10:25 +0000, Jonathan Cameron wrote:

On 12/01/15 01:57, Srinivas Pandruvada wrote:

quoted

Add additional flag to read in async mode. In this mode the caller will get
reply via registered callback for capture_sample. Callbacks can be registered
using sensor_hub_register_callback function. The usage id parameter of the
capture_sample can be matched with the usage id of the requested attribute.

Signed-off-by: Srinivas Pandruvada <redacted>

Looks like a straightforward 'pattern' to me.  Only real question is whether
reversing the logic in the read function to make the synchronous case the
one that has the if statement would lead to a cleaner result?

Submitted new version with the suggested change, by reversing the logic.

Thanks,
Srinivas

quoted

---
 drivers/hid/hid-sensor-hub.c                  | 15 ++++++++++++++-
 drivers/iio/accel/hid-sensor-accel-3d.c       |  3 ++-
 drivers/iio/gyro/hid-sensor-gyro-3d.c         |  3 ++-
 drivers/iio/light/hid-sensor-als.c            |  3 ++-
 drivers/iio/light/hid-sensor-prox.c           |  3 ++-
 drivers/iio/magnetometer/hid-sensor-magn-3d.c |  3 ++-
 drivers/iio/orientation/hid-sensor-incl-3d.c  |  3 ++-
 drivers/iio/pressure/hid-sensor-press.c       |  3 ++-
 drivers/rtc/rtc-hid-sensor-time.c             |  2 +-
 include/linux/hid-sensor-hub.h                | 19 +++++++++++++------
 10 files changed, 42 insertions(+), 15 deletions(-)

diff --git a/drivers/hid/hid-sensor-hub.c b/drivers/hid/hid-sensor-hub.c
index 8bed109..7403b25 100644
--- a/drivers/hid/hid-sensor-hub.c
+++ b/drivers/hid/hid-sensor-hub.c

@@ -275,13 +275,26 @@ EXPORT_SYMBOL_GPL(sensor_hub_get_feature);
 
 int sensor_hub_input_attr_get_raw_value(struct hid_sensor_hub_device *hsdev,
 					u32 usage_id,
-					u32 attr_usage_id, u32 report_id)
+					u32 attr_usage_id, u32 report_id,
+					enum sensor_hub_read_flags flag)
 {
 	struct sensor_hub_data *data = hid_get_drvdata(hsdev->hdev);
 	unsigned long flags;
 	struct hid_report *report;
 	int ret_val = 0;

This seems a little backwards from the normal case where we have
additional stuff (e.g. under an if) for the synchronous case
than the the asynchronous case.  That would require (I think)
2 or 3 if blocks, rather than the one.  It does look like
reorgansing the synchronous case to pull the report creation
earlier would reduce the time the mutex is held and make
it easier to separate out the synchronous only parts...

What do you think?

This is clearly the least invasive patch necessary, but seems
like the resulting code is slightly less clean than it would
otherwise be, with slightly more repitition...

quoted

+	if (flag == SENSOR_HUB_ASYNC) {
+		report = sensor_hub_report(report_id, hsdev->hdev,
+					   HID_INPUT_REPORT);
+		if (!report)
+			return -EINVAL;
+
+		mutex_lock(&data->mutex);
+		hid_hw_request(hsdev->hdev, report, HID_REQ_GET_REPORT);
+		mutex_unlock(&data->mutex);
+		return 0;
+	}
+
 	mutex_lock(&hsdev->mutex);
 	memset(&hsdev->pending, 0, sizeof(hsdev->pending));
 	init_completion(&hsdev->pending.ready);

diff --git a/drivers/iio/accel/hid-sensor-accel-3d.c b/drivers/iio/accel/hid-sensor-accel-3d.c
index d5d9531..0085c2f 100644
--- a/drivers/iio/accel/hid-sensor-accel-3d.c
+++ b/drivers/iio/accel/hid-sensor-accel-3d.c

@@ -130,7 +130,8 @@ static int accel_3d_read_raw(struct iio_dev *indio_dev,
 			*val = sensor_hub_input_attr_get_raw_value(
 					accel_state->common_attributes.hsdev,
 					HID_USAGE_SENSOR_ACCEL_3D, address,
-					report_id);
+					report_id,
+					SENSOR_HUB_SYNC);
 		else {
 			*val = 0;
 			hid_sensor_power_state(&accel_state->common_attributes,

diff --git a/drivers/iio/gyro/hid-sensor-gyro-3d.c b/drivers/iio/gyro/hid-sensor-gyro-3d.c
index a3ea1e8..bdcd105 100644
--- a/drivers/iio/gyro/hid-sensor-gyro-3d.c
+++ b/drivers/iio/gyro/hid-sensor-gyro-3d.c

@@ -130,7 +130,8 @@ static int gyro_3d_read_raw(struct iio_dev *indio_dev,
 			*val = sensor_hub_input_attr_get_raw_value(
 					gyro_state->common_attributes.hsdev,
 					HID_USAGE_SENSOR_GYRO_3D, address,
-					report_id);
+					report_id,
+					SENSOR_HUB_SYNC);
 		else {
 			*val = 0;
 			hid_sensor_power_state(&gyro_state->common_attributes,

diff --git a/drivers/iio/light/hid-sensor-als.c b/drivers/iio/light/hid-sensor-als.c
index a5283d7..321862d 100644
--- a/drivers/iio/light/hid-sensor-als.c
+++ b/drivers/iio/light/hid-sensor-als.c

@@ -109,7 +109,8 @@ static int als_read_raw(struct iio_dev *indio_dev,
 			*val = sensor_hub_input_attr_get_raw_value(
 					als_state->common_attributes.hsdev,
 					HID_USAGE_SENSOR_ALS, address,
-					report_id);
+					report_id,
+					SENSOR_HUB_SYNC);
 			hid_sensor_power_state(&als_state->common_attributes,
 						false);
 		} else {

diff --git a/drivers/iio/light/hid-sensor-prox.c b/drivers/iio/light/hid-sensor-prox.c
index f5a5146..db9c60e 100644
--- a/drivers/iio/light/hid-sensor-prox.c
+++ b/drivers/iio/light/hid-sensor-prox.c

@@ -105,7 +105,8 @@ static int prox_read_raw(struct iio_dev *indio_dev,
 			*val = sensor_hub_input_attr_get_raw_value(
 				prox_state->common_attributes.hsdev,
 				HID_USAGE_SENSOR_PROX, address,
-				report_id);
+				report_id,
+				SENSOR_HUB_SYNC);
 			hid_sensor_power_state(&prox_state->common_attributes,
 						false);
 		} else {

diff --git a/drivers/iio/magnetometer/hid-sensor-magn-3d.c b/drivers/iio/magnetometer/hid-sensor-magn-3d.c
index 6294575..4d299f3 100644
--- a/drivers/iio/magnetometer/hid-sensor-magn-3d.c
+++ b/drivers/iio/magnetometer/hid-sensor-magn-3d.c

@@ -178,7 +178,8 @@ static int magn_3d_read_raw(struct iio_dev *indio_dev,
 			*val = sensor_hub_input_attr_get_raw_value(
 				magn_state->common_attributes.hsdev,
 				HID_USAGE_SENSOR_COMPASS_3D, address,
-				report_id);
+				report_id,
+				SENSOR_HUB_SYNC);
 		else {
 			*val = 0;
 			hid_sensor_power_state(&magn_state->common_attributes,

diff --git a/drivers/iio/orientation/hid-sensor-incl-3d.c b/drivers/iio/orientation/hid-sensor-incl-3d.c
index 1ff181b..45bed08 100644
--- a/drivers/iio/orientation/hid-sensor-incl-3d.c
+++ b/drivers/iio/orientation/hid-sensor-incl-3d.c

@@ -132,7 +132,8 @@ static int incl_3d_read_raw(struct iio_dev *indio_dev,
 			*val = sensor_hub_input_attr_get_raw_value(
 				incl_state->common_attributes.hsdev,
 				HID_USAGE_SENSOR_INCLINOMETER_3D, address,
-				report_id);
+				report_id,
+				SENSOR_HUB_SYNC);
 		else {
 			hid_sensor_power_state(&incl_state->common_attributes,
 						false);

diff --git a/drivers/iio/pressure/hid-sensor-press.c b/drivers/iio/pressure/hid-sensor-press.c
index 7649286..ac150f0 100644
--- a/drivers/iio/pressure/hid-sensor-press.c
+++ b/drivers/iio/pressure/hid-sensor-press.c

@@ -108,7 +108,8 @@ static int press_read_raw(struct iio_dev *indio_dev,
 			*val = sensor_hub_input_attr_get_raw_value(
 				press_state->common_attributes.hsdev,
 				HID_USAGE_SENSOR_PRESSURE, address,
-				report_id);
+				report_id,
+				SENSOR_HUB_SYNC);
 			hid_sensor_power_state(&press_state->common_attributes,
 						false);
 		} else {

diff --git a/drivers/rtc/rtc-hid-sensor-time.c b/drivers/rtc/rtc-hid-sensor-time.c
index ae7c2ba..af4f85a 100644
--- a/drivers/rtc/rtc-hid-sensor-time.c
+++ b/drivers/rtc/rtc-hid-sensor-time.c

@@ -213,7 +213,7 @@ static int hid_rtc_read_time(struct device *dev, struct rtc_time *tm)
 	/* get a report with all values through requesting one value */
 	sensor_hub_input_attr_get_raw_value(time_state->common_attributes.hsdev,
 			HID_USAGE_SENSOR_TIME, hid_time_addresses[0],
-			time_state->info[0].report_id);
+			time_state->info[0].report_id, SENSOR_HUB_SYNC);
 	/* wait for all values (event) */
 	ret = wait_for_completion_killable_timeout(
 			&time_state->comp_last_time, HZ*6);

diff --git a/include/linux/hid-sensor-hub.h b/include/linux/hid-sensor-hub.h
index a51c768..d48e91f 100644
--- a/include/linux/hid-sensor-hub.h
+++ b/include/linux/hid-sensor-hub.h

@@ -171,20 +171,27 @@ int sensor_hub_input_get_attribute_info(struct hid_sensor_hub_device *hsdev,
 			struct hid_sensor_hub_attribute_info *info);
 
 /**
-* sensor_hub_input_attr_get_raw_value() - Synchronous read request
+* sensor_hub_input_attr_get_raw_value() - Attribute read request
 * @hsdev:	Hub device instance.
 * @usage_id:	Attribute usage id of parent physical device as per spec
 * @attr_usage_id:	Attribute usage id as per spec
 * @report_id:	Report id to look for
+* @flag:	Synchronour or asynchronous read
 *
-* Issues a synchronous read request for an input attribute. Returns
-* data upto 32 bits. Since client can get events, so this call should
-* not be used for data paths, this will impact performance.
+* Issues a synchronous or asynchronous read request for an input attribute.
+* Returns data upto 32 bits.
 */
 
+enum sensor_hub_read_flags {
+	SENSOR_HUB_SYNC,
+	SENSOR_HUB_ASYNC,
+};
+
 int sensor_hub_input_attr_get_raw_value(struct hid_sensor_hub_device *hsdev,
-			u32 usage_id,
-			u32 attr_usage_id, u32 report_id);
+					u32 usage_id,
+					u32 attr_usage_id, u32 report_id,
+					enum sensor_hub_read_flags flag
+);
 /**
 * sensor_hub_set_feature() - Feature set request
 * @hsdev:	Hub device instance.