This is a note to let you know that I've just added the patch titled
iio: hid-sensor-trigger: Fix sometimes not powering up the sensor
to my staging git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From 6f92253024d9d947a4f454654840ce479e251376 Mon Sep 17 00:00:00 2001
From: Hans de Goede <hdegoede@xxxxxxxxxx>
Date: Sat, 14 Apr 2018 17:09:09 +0200
Subject: iio: hid-sensor-trigger: Fix sometimes not powering up the sensor
after resume
hid_sensor_set_power_work() powers the sensors back up after a resume
based on the user_requested_state atomic_t.
But hid_sensor_power_state() treats this as a boolean flag, leading to
the following problematic scenario:
1) Some app starts using the iio-sensor in buffered / triggered mode,
hid_sensor_data_rdy_trigger_set_state(true) gets called, setting
user_requested_state to 1.
2) Something directly accesses a _raw value through sysfs, leading
to a call to hid_sensor_power_state(true) followed by
hid_sensor_power_state(false) call, this sets user_requested_state
to 1 followed by setting it to 0.
3) Suspend/resume the machine, hid_sensor_set_power_work() now does
NOT power the sensor back up because user_requested_state (wrongly)
is 0. Which stops the app using the sensor in buffered mode from
receiving any new values.
This commit changes user_requested_state to a counter tracking how many
times hid_sensor_power_state(true) was called instead, fixing this.
Cc: Bastien Nocera <hadess@xxxxxxxxxx>
Cc: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>
Cc: <Stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
---
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 cfb6588565ba..4905a997a7ec 100644
--- a/drivers/iio/common/hid-sensors/hid-sensor-trigger.c
+++ b/drivers/iio/common/hid-sensors/hid-sensor-trigger.c
@@ -178,14 +178,14 @@ 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 (atomic_add_unless(&st->runtime_pm_enable, 1, 1))
pm_runtime_enable(&st->pdev->dev);
- if (state)
+ if (state) {
+ atomic_inc(&st->user_requested_state);
ret = pm_runtime_get_sync(&st->pdev->dev);
- else {
+ } else {
+ atomic_dec(&st->user_requested_state);
pm_runtime_mark_last_busy(&st->pdev->dev);
pm_runtime_use_autosuspend(&st->pdev->dev);
ret = pm_runtime_put_autosuspend(&st->pdev->dev);
--
2.17.0
