Am Mittwoch, dem 05.04.2023 um 15:52 +0300 schrieb Sakari Ailus:
> Hi Martin,
>
> On Wed, Apr 05, 2023 at 11:29:03AM +0200, Martin Kepplinger wrote:
> > pm_runtime_get_if_in_use() does not only return nonzero values when
> > the device is in use, it can return a negative errno too.
> >
> > And especially during resuming from system suspend, when runtime pm
> > is not yet up again, this can very well happen. And in such a case
> > the subsequent pm_runtime_put() call would result in a refcount
> > underflow!
>
> I think this issue should have a more generic solution, it's very
> difficult
> to address this in drivers only with the current APIs.
>
> pm_runtime_get_if_in_use() will also return an error if runtime PM is
> disabled, so this patch will break the driver for that configuration.
ok but the driver is currently broken for any *other* error returned by
pm_runtime_get_if_in_use() (than the runtime-PM disabled error).
The execution-path during system-resume I'm interested in gets -EAGAIN
here. Would it be ok for you if I'd return early only for that one
error only here?
>
> >
> > Fix it by correctly using pm_runtime_get_if_in_use().
> >
> > Signed-off-by: Martin Kepplinger <martin.kepplinger@xxxxxxx>
> > ---
> > drivers/media/i2c/hi846.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/media/i2c/hi846.c b/drivers/media/i2c/hi846.c
> > index 5b5ea5425e984..0b0eda2e223cd 100644
> > --- a/drivers/media/i2c/hi846.c
> > +++ b/drivers/media/i2c/hi846.c
> > @@ -1544,7 +1544,7 @@ static int hi846_set_ctrl(struct v4l2_ctrl
> > *ctrl)
> > exposure_max);
> > }
> >
> > - if (!pm_runtime_get_if_in_use(&client->dev))
> > + if (pm_runtime_get_if_in_use(&client->dev) <= 0)
> > return 0;
> >
> > switch (ctrl->id) {
>
