On 22/02/17 05:40, Pandruvada, Srinivas wrote:

On Wed, 2017-02-22 at 17:17 +0800, Song Hongyan wrote:

quoted

In function _hid_sensor_power_state(), when
hid_sensor_read_poll_value()
is called, sensor's all properties will be updated by the value from
sensor hardware/firmware.
In some implementation, sensor hardware/firmware will do a power
cycle
during S3. In this case, after resume, once
hid_sensor_read_poll_value()
is called, sensor's all properties which are kept by driver during S3
will be changed to default value.
But instead, if a set feature function is called first, sensor
hardware/firmware will be recovered to the last status. So change the
sensor_hub_set_feature() calling order to behind of set feature
function
to avoid sensor properties lose.

Signed-off-by: Song Hongyan <redacted>

Acked-by: Srinivas Pandruvada <srinivas.pandruvada-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>

Hi Song,

The patch message, whilst excellent on the technical detail, gives me
no sense of urgency on this. Is this a fix we want to have heading for
stable ASAP or are we looking at something seen in some developmental
hardware for example?
Links to bug reports, or examples of hardware suffering from the issue
are always helpful as well.

Also for something like this a 'fixes' tag is very helpful when people
are looking to back port it.

Anyhow, I'm going to hold off on taking this one until I have more
information. Right now it makes little difference as the next fixes
pull request from me will probably not be until next weekend.

Thanks,

Jonathan

quoted

---
 drivers/iio/common/hid-sensors/hid-sensor-trigger.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/common/hid-sensors/hid-sensor-trigger.c

b/drivers/iio/common/hid-sensors/hid-sensor-trigger.c
index a3cce3a..ecf592d 100644

--- a/drivers/iio/common/hid-sensors/hid-sensor-trigger.c
+++ b/drivers/iio/common/hid-sensors/hid-sensor-trigger.c

@@ -51,8 +51,6 @@ static int _hid_sensor_power_state(struct

hid_sensor_common *st, bool state)
 			st->report_state.report_id,
 			st->report_state.index,
 			HID_USAGE_SENSOR_PROP_REPORTING_STATE_ALL_EV
ENTS_ENUM);
-
-		poll_value = hid_sensor_read_poll_value(st);
 	} else {
 		int val;
 

@@ -89,7 +87,9 @@ static int _hid_sensor_power_state(struct

hid_sensor_common *st, bool state)
 	sensor_hub_get_feature(st->hsdev, st->power_state.report_id,
 			       st->power_state.index,
 			       sizeof(state_val), &state_val);
-	if (state && poll_value)
+	if (state)
+		poll_value = hid_sensor_read_poll_value(st);
+	if (poll_value > 0)
 		msleep_interruptible(poll_value * 2);
 
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