On Sat, 14 Apr 2018 17:09:09 +0200
Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
> 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>
Looks sensible to me.
I'll give it a few days at least though for others to comment.
Thanks,
Jonathan
> ---
> 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);
--
To unsubscribe from this list: send the line "unsubscribe linux-iio" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
