Messages in this thread | | | Date | Wed, 5 Apr 2023 15:52:52 +0300 | From | Sakari Ailus <> | Subject | Re: [PATCH v1 1/2] media: hi846: fix usage of pm_runtime_get_if_in_use() |
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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.
> > Fix it by correctly using pm_runtime_get_if_in_use(). > > Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm> > --- > 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) {
-- Kind regards,
Sakari Ailus
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