Patch "hid-sensor: Fix suspend/resume delay" has been added to the 4.1-stable tree

This is a note to let you know that I've just added the patch titled

hid-sensor: Fix suspend/resume delay

to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
hid-sensor-fix-suspend-resume-delay.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Srinivas Pandruvada <[email protected]>
Date: Mon, 1 Jun 2015 16:36:27 -0700
Subject: hid-sensor: Fix suspend/resume delay

From: Srinivas Pandruvada <[email protected]>

commit 1e25aa9641e8f3fa39cd5e46b4afcafd7f12a44b upstream.

By default all the sensors are runtime suspended state (lowest power state). During Linux suspend process, all the run time suspended devices are resumed and then suspended. This caused all sensors to power up and introduced delay in suspend time, when we introduced runtime PM for HID sensors. The opposite process happens during resume process.

To fix this, we do powerup process of the sensors only when the request is issued from user (raw or tiggerred). In this way when runtime, resume calls for powerup it will simply return as this will not match user requested state.

Note this is a regression fix as the increase in suspend / resume times can be substantial (report of 8 seconds on Len's laptop!)

---
 drivers/iio/common/hid-sensors/hid-sensor-trigger.c |   11 ++++++++++-
 include/linux/hid-sensor-hub.h                      |    1 +
 2 files changed, 11 insertions(+), 1 deletion(-)

@@ -36,6 +36,8 @@ static int _hid_sensor_power_state(struc
 	s32 poll_value = 0;
 
 	if (state) {
+		if (!atomic_read(&st->user_requested_state))
+			return 0;
 		if (sensor_hub_device_open(st->hsdev))
 			return -EIO;
 

@@ -52,8 +54,12 @@ static int _hid_sensor_power_state(struc
 
 		poll_value = hid_sensor_read_poll_value(st);
 	} else {
-		if (!atomic_dec_and_test(&st->data_ready))
+		int val;
+
+		val = atomic_dec_if_positive(&st->data_ready);
+		if (val < 0)
 			return 0;
+
 		sensor_hub_device_close(st->hsdev);
 		state_val = hid_sensor_get_usage_index(st->hsdev,
 			st->power_state.report_id,

@@ -92,9 +98,11 @@ EXPORT_SYMBOL(hid_sensor_power_state);
 
 int hid_sensor_power_state(struct hid_sensor_common *st, bool state)
 {
+
 #ifdef CONFIG_PM
 	int ret;
 
+	atomic_set(&st->user_requested_state, state);
 	if (state)
 		ret = pm_runtime_get_sync(&st->pdev->dev);
 	else {

@@ -109,6 +117,7 @@ int hid_sensor_power_state(struct hid_se
 
  	return 0;
 #else
+	atomic_set(&st->user_requested_state, state);
 	return _hid_sensor_power_state(st, state);
 #endif
 }

@@ -230,6 +230,7 @@ struct hid_sensor_common {
 	struct platform_device *pdev;
 	unsigned usage_id;
 	atomic_t data_ready;
+	atomic_t user_requested_state;
 	struct iio_trigger *trigger;
 	struct hid_sensor_hub_attribute_info poll;
 	struct hid_sensor_hub_attribute_info report_state;

Patches currently in stable-queue which might be from [email protected] are

queue-4.1/hid-sensor-fix-suspend-resume-delay.patch