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@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) {
--
Kind regards,
Sakari Ailus
