diff mbox series

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

Message ID 20231117111433.1561669-7-sakari.ailus@linux.intel.com (mailing list archive)
State Changes Requested, archived
Headers show
Series Small Runtime PM API changes | expand

Commit Message

Sakari Ailus Nov. 17, 2023, 11:14 a.m. UTC
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.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/media/i2c/imx319.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

Comments

Laurent Pinchart Nov. 18, 2023, 6:52 p.m. UTC | #1
Hi Sakari,

Thank you for the patch.

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() ?

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;
>  }
Sakari Ailus Nov. 20, 2023, 9:32 a.m. UTC | #2
Hi Laurent,

On Sat, Nov 18, 2023 at 08:52:48PM +0200, Laurent Pinchart wrote:
> Hi Sakari,
> 
> Thank you for the patch.
> 
> 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.

> 
> 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;
> >  }
>
Laurent Pinchart Nov. 20, 2023, 9:45 a.m. UTC | #3
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.

> > 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;
> > >  }
Sakari Ailus Nov. 21, 2023, 8:18 a.m. UTC | #4
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;
> > > >  }
>
Laurent Pinchart Nov. 21, 2023, 8:25 a.m. UTC | #5
On Tue, Nov 21, 2023 at 08:18:24AM +0000, Sakari Ailus wrote:
> 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).

But what's the drawback of using pm_runtime_get_if_active() in all cases
(for camera sensor drivers) ? The semantics in the .s_ctrl() handler is
"I want to proceed only if the device is powered on", and that's exactly
what pm_runtime_get_if_active() gives us. The semantics of using
pm_runtime_get_if_in_use() is "I want to proceed if someone else is
holding a reference". It happens to give the same practical result as
pm_runtime_get_if_active() when not using autosuspend, but it's still
not the right semantics.

> > > > 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;
> > > > >  }
Sakari Ailus Nov. 21, 2023, 8:44 a.m. UTC | #6
Hi Laurent,

On Tue, Nov 21, 2023 at 10:25:35AM +0200, Laurent Pinchart wrote:
> On Tue, Nov 21, 2023 at 08:18:24AM +0000, Sakari Ailus wrote:
> > 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).
> 
> But what's the drawback of using pm_runtime_get_if_active() in all cases
> (for camera sensor drivers) ? The semantics in the .s_ctrl() handler is
> "I want to proceed only if the device is powered on", and that's exactly
> what pm_runtime_get_if_active() gives us. The semantics of using
> pm_runtime_get_if_in_use() is "I want to proceed if someone else is
> holding a reference". It happens to give the same practical result as
> pm_runtime_get_if_active() when not using autosuspend, but it's still
> not the right semantics.

Well, using the _active() variant here may introduce an unneeded write
operation so that isn't actually an issue. But using the _if_in_use()
variant in a driver using autosuspend may lead to missing a write --- as it
returns 0 if the usage_count is 0 even if the device is in active state. Oh
well.

I can change the driver to use autosuspend but I think I'll split the set
into two, one doing the Runtime PM API changes and another to address
issues in sensor drivers.

> 
> > > > > 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;
> > > > > >  }
>
diff mbox series

Patch

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;
 }