Re: [PATCH v2 6/7] media: imx319: Put usage_count correctly in s_ctrl callback

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Hi Laurent,

On Mon, Nov 20, 2023 at 11:45:03AM +0200, Laurent Pinchart wrote:
> On Mon, Nov 20, 2023 at 09:32:10AM +0000, Sakari Ailus wrote:
> > On Sat, Nov 18, 2023 at 08:52:48PM +0200, Laurent Pinchart wrote:
> > > On Fri, Nov 17, 2023 at 01:14:32PM +0200, Sakari Ailus wrote:
> > > > pm_runtime_get_if_in_use() returns an error if Runtime PM is disabled for
> > > > the device, in which case it won't increment the use count.
> > > > pm_runtime_put() does that unconditionally however. Only call
> > > > pm_runtime_put() in case pm_runtime_get_if_in_use() has returned a value >
> > > > 0.
> > > 
> > > Why don't you use pm_runtime_get_if_active() ?
> > 
> > It's only meaningful if the driver uses autosuspend. The imx319 driver does
> > not.
> 
> Does pm_runtime_get_if_active() causes issues with the driver uses
> autosuspend ? Standardizing on a single API that covers all the use
> cases would increase consistency and make the code base easier to
> understand. Beside, the driver should switch to autosuspend :-) Using
> the correct RPM calls already is a good thing, if they don't introduce
> any issue.

Both are fine but they're there for a different purpose. The driver should
consistently use either usage_count or status based calls (for autosuspend
to make sense).

> 
> > > Other than that, same comment as for patch 5/7, I don't like the
> > > increased complexity.
> > > 
> > > These comments apply to 7/7 as well.
> > > 
> > > > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > > > ---
> > > >  drivers/media/i2c/imx319.c | 8 +++++---
> > > >  1 file changed, 5 insertions(+), 3 deletions(-)
> > > > 
> > > > diff --git a/drivers/media/i2c/imx319.c b/drivers/media/i2c/imx319.c
> > > > index 5378f607f340..e7b2d0c20d29 100644
> > > > --- a/drivers/media/i2c/imx319.c
> > > > +++ b/drivers/media/i2c/imx319.c
> > > > @@ -1880,8 +1880,8 @@ static int imx319_set_ctrl(struct v4l2_ctrl *ctrl)
> > > >  	struct imx319 *imx319 = container_of(ctrl->handler,
> > > >  					     struct imx319, ctrl_handler);
> > > >  	struct i2c_client *client = v4l2_get_subdevdata(&imx319->sd);
> > > > +	int ret, pm_status;
> > > >  	s64 max;
> > > > -	int ret;
> > > >  
> > > >  	/* Propagate change of current control to all related controls */
> > > >  	switch (ctrl->id) {
> > > > @@ -1898,7 +1898,8 @@ static int imx319_set_ctrl(struct v4l2_ctrl *ctrl)
> > > >  	 * Applying V4L2 control value only happens
> > > >  	 * when power is up for streaming
> > > >  	 */
> > > > -	if (!pm_runtime_get_if_in_use(&client->dev))
> > > > +	pm_status = pm_runtime_get_if_in_use(&client->dev);
> > > > +	if (!pm_status)
> > > >  		return 0;
> > > >  
> > > >  	switch (ctrl->id) {
> > > > @@ -1937,7 +1938,8 @@ static int imx319_set_ctrl(struct v4l2_ctrl *ctrl)
> > > >  		break;
> > > >  	}
> > > >  
> > > > -	pm_runtime_put(&client->dev);
> > > > +	if (pm_status > 0)
> > > > +		pm_runtime_put(&client->dev);
> > > >  
> > > >  	return ret;
> > > >  }
> 

-- 
Regards,

Sakari Ailus