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

[Srinivas Pandruvada <srinivas.pandruvada-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

On Sun, 2015-02-01 at 10:25 +0000, Jonathan Cameron wrote:
> On 12/01/15 01:57, Srinivas Pandruvada wrote:
> > 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 <srinivas.pandruvada-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> 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

> > ---
> >  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...
> > +	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.
> > 
>