On Sun, 2018-04-15 at 15:58 +0100, Jonathan Cameron wrote:
> 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>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>
Which App is doing like this?
Thanks,
Srinivas
>
> 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);
>
>
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