Fix for iio race

iio-race-fix.patch

@@ -0,0 +1,83 @@
+From eafad73ed3851707fa6e3124a255fc049ff9545d Mon Sep 17 00:00:00 2001
+From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
+Date: Sat, 12 Aug 2017 09:09:21 -0700
+Subject: iio: hid-sensor-trigger: Fix the race with user space powering up
+ sensors
+
+It has been reported for a while that with iio-sensor-proxy service the
+rotation only works after one suspend/resume cycle. This required a wait
+in the systemd unit file to avoid race. I found a Yoga 900 where I could
+reproduce this.
+
+The problem scenerio is:
+- During sensor driver init, enable run time PM and also set a
+  auto-suspend for 3 seconds.
+	This result in one runtime resume. But there is a check to avoid
+a powerup in this sequence, but rpm is active
+- User space iio-sensor-proxy tries to power up the sensor. Since rpm is
+  active it will simply return. But sensors were not actually
+powered up in the prior sequence, so actaully the sensors will not work
+- After 3 seconds the auto suspend kicks
+
+If we add a wait in systemd service file to fire iio-sensor-proxy after
+3 seconds, then now everything will work as the runtime resume will
+actually powerup the sensor as this is a user request.
+
+To avoid this:
+- Remove the check to match user requested state, this will cause a
+  brief powerup, but if the iio-sensor-proxy starts immediately it will
+still work as the sensors are ON.
+- Also move the autosuspend delay to place when user requested turn off
+  of sensors, like after user finished raw read or buffer disable
+
+Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
+Tested-by: Bastien Nocera <hadess@hadess.net>
+Cc: <Stable@vger.kernel.org>
+Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
+---
+ drivers/iio/common/hid-sensors/hid-sensor-trigger.c | 8 ++++----
+ 1 file changed, 4 insertions(+), 4 deletions(-)
+
+diff --git a/drivers/iio/common/hid-sensors/hid-sensor-trigger.c b/drivers/iio/common/hid-sensors/hid-sensor-trigger.c
+index 16ade0a..0e4b379 100644
+--- a/drivers/iio/common/hid-sensors/hid-sensor-trigger.c
++++ b/drivers/iio/common/hid-sensors/hid-sensor-trigger.c
+@@ -111,8 +111,6 @@ static int _hid_sensor_power_state(struct hid_sensor_common *st, bool state)
+ 	s32 poll_value = 0;
+ 
+ 	if (state) {
+-		if (!atomic_read(&st->user_requested_state))
+-			return 0;
+ 		if (sensor_hub_device_open(st->hsdev))
+ 			return -EIO;
+ 
+@@ -161,6 +159,9 @@ static int _hid_sensor_power_state(struct hid_sensor_common *st, bool state)
+ 				       &report_val);
+ 	}
+ 
++	pr_debug("HID_SENSOR %s set power_state %d report_state %d\n",
++		 st->pdev->name, state_val, report_val);
++
+ 	sensor_hub_get_feature(st->hsdev, st->power_state.report_id,
+ 			       st->power_state.index,
+ 			       sizeof(state_val), &state_val);
+@@ -182,6 +183,7 @@ int hid_sensor_power_state(struct hid_sensor_common *st, bool state)
+ 		ret = pm_runtime_get_sync(&st->pdev->dev);
+ 	else {
+ 		pm_runtime_mark_last_busy(&st->pdev->dev);
++		pm_runtime_use_autosuspend(&st->pdev->dev);
+ 		ret = pm_runtime_put_autosuspend(&st->pdev->dev);
+ 	}
+ 	if (ret < 0) {
+@@ -285,8 +287,6 @@ int hid_sensor_setup_trigger(struct iio_dev *indio_dev, const char *name,
+ 	/* Default to 3 seconds, but can be changed from sysfs */
+ 	pm_runtime_set_autosuspend_delay(&attrb->pdev->dev,
+ 					 3000);
+-	pm_runtime_use_autosuspend(&attrb->pdev->dev);
+-
+ 	return ret;
+ error_unreg_trigger:
+ 	iio_trigger_unregister(trig);
+-- 
+cgit v1.1
+

kernel.spec

@@ -646,6 +646,9 @@ Patch616: 0016-Input-silead-Do-not-try-to-directly-access-the-GPIO-.patch
 # rhbz 1476467
 Patch617: Fix-for-module-sig-verification.patch
 
+# request for bug fix
+Patch618: iio-race-fix.patch
+
 # END OF PATCH DEFINITIONS
 
 %endif
@@ -2199,6 +2202,9 @@ fi
 #
 #
 %changelog
+* Wed Aug 16 2017 Laura Abbott <labbott@redhat.com>
+- Fix for iio race
+
 * Wed Aug 16 2017 Hans de Goede <jwrdegoede@fedoraproject.org>
 - Enable CONFIG_DRM_VBOXVIDEO=m on x86
 - Enable CONFIG_R8188EU=m on x86_64, some Cherry Trail devices use this