Hi Mauro,
On Wed, May 05, 2021 at 12:57:00PM +0200, Mauro Carvalho Chehab wrote:
> Em Wed, 5 May 2021 13:34:09 +0300
> Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> escreveu:
>
> > Hi Mauro,
> >
> > Thanks for the patch.
> >
> > On Wed, May 05, 2021 at 11:42:15AM +0200, Mauro Carvalho Chehab wrote:
> > > The pm_runtime_get_sync() internally increments the
> > > dev->power.usage_count without decrementing it, even on errors.
> > >
> > > There is a bug at ccs_pm_get_init(): when this function returns
> > > an error, the stream is not started, and RPM usage_count
> > > should not be incremented. However, if the calls to
> > > v4l2_ctrl_handler_setup() return errors, it will be kept
> > > incremented.
> > >
> > > At ccs_suspend() the best is to replace it by the new
> > > pm_runtime_resume_and_get(), introduced by:
> > > commit dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter")
> > > in order to properly decrement the usage counter automatically,
> > > in the case of errors.
> > >
> > > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
> >
> > Could you add Fixes: line and Cc: stable?
>
> Sure. See the fixes one enclosed.
>
> > The patch that breaks this is 96e3a6b92f23a .
> >
> > It would be better to fix the bug first so the patch to the stable trees
> > doesn't need special handling.
Please ignore this comment.
> >
> > > ---
> > > drivers/media/i2c/ccs/ccs-core.c | 39 ++++++++++++++++++++------------
> > > 1 file changed, 24 insertions(+), 15 deletions(-)
> > >
> > > diff --git a/drivers/media/i2c/ccs/ccs-core.c b/drivers/media/i2c/ccs/ccs-core.c
> > > index b05f409014b2..04c3ab9e37b4 100644
> > > --- a/drivers/media/i2c/ccs/ccs-core.c
> > > +++ b/drivers/media/i2c/ccs/ccs-core.c
> > > @@ -1880,21 +1880,33 @@ static int ccs_pm_get_init(struct ccs_sensor *sensor)
> > > struct i2c_client *client = v4l2_get_subdevdata(&sensor->src->sd);
> > > int rval;
> > >
> > > + /*
> > > + * It can't use pm_runtime_resume_and_get() here, as the driver
> > > + * relies at the returned value to detect if the device was already
> > > + * active or not.
> > > + */
> > > rval = pm_runtime_get_sync(&client->dev);
> > > - if (rval < 0) {
> > > - pm_runtime_put_noidle(&client->dev);
> > > + if (rval < 0)
> > > + goto error;
> > >
> > > - return rval;
> > > - } else if (!rval) {
> > > - rval = v4l2_ctrl_handler_setup(&sensor->pixel_array->
> > > - ctrl_handler);
> > > - if (rval)
> > > - return rval;
> > > + /* Device was already active, so don't set controls */
> > > + if (rval == 1)
> > > + return 0;
> > >
> > > - return v4l2_ctrl_handler_setup(&sensor->src->ctrl_handler);
> > > - }
> > > + /* Restore V4L2 controls to the suspended device */
> > > + rval = v4l2_ctrl_handler_setup(&sensor->pixel_array->ctrl_handler);
> > > + if (rval)
> > > + goto error;
> > >
> > > + rval = v4l2_ctrl_handler_setup(&sensor->src->ctrl_handler);
> > > + if (rval)
> > > + goto error;
> > > +
> > > + /* Keep PM runtime usage_count incremented on success */
> > > return 0;
> > > +error:
> > > + pm_runtime_put_noidle(&client->dev);
> >
> > This needs to be pm_runtime_put() as the device has been successfully.
>
> Ok.
>
> >
> > > + return rval;
> > > }
> > >
> > > static int ccs_set_stream(struct v4l2_subdev *subdev, int enable)
> > > @@ -3089,12 +3101,9 @@ static int __maybe_unused ccs_suspend(struct device *dev)
> > > bool streaming = sensor->streaming;
> > > int rval;
> > >
> > > - rval = pm_runtime_get_sync(dev);
> > > - if (rval < 0) {
> > > - pm_runtime_put_noidle(dev);
> > > -
> > > + rval = pm_runtime_resume_and_get(dev);
> > > + if (rval < 0)
> > > return rval;
> > > - }
> > >
> > > if (sensor->streaming)
> > > ccs_stop_streaming(sensor);
> >
>
> Thanks,
> Mauro
>
> ---
>
> [PATCH] media: i2c: ccs-core: fix pm_runtime_get_sync() usage count
>
> The pm_runtime_get_sync() internally increments the
> dev->power.usage_count without decrementing it, even on errors.
>
> There is a bug at ccs_pm_get_init(): when this function returns
> an error, the stream is not started, and RPM usage_count
> should not be incremented. However, if the calls to
> v4l2_ctrl_handler_setup() return errors, it will be kept
> incremented.
>
> At ccs_suspend() the best is to replace it by the new
> pm_runtime_resume_and_get(), introduced by:
> commit dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter")
> in order to properly decrement the usage counter automatically,
> in the case of errors.
>
> Fixes: 96e3a6b92f23 ("media: smiapp: Avoid maintaining power state information")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
Acked-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
>
> diff --git a/drivers/media/i2c/ccs/ccs-core.c b/drivers/media/i2c/ccs/ccs-core.c
> index b05f409014b2..5ea471fefa3a 100644
> --- a/drivers/media/i2c/ccs/ccs-core.c
> +++ b/drivers/media/i2c/ccs/ccs-core.c
> @@ -1880,21 +1880,33 @@ static int ccs_pm_get_init(struct ccs_sensor *sensor)
> struct i2c_client *client = v4l2_get_subdevdata(&sensor->src->sd);
> int rval;
>
> + /*
> + * It can't use pm_runtime_resume_and_get() here, as the driver
> + * relies at the returned value to detect if the device was already
> + * active or not.
> + */
> rval = pm_runtime_get_sync(&client->dev);
> - if (rval < 0) {
> - pm_runtime_put_noidle(&client->dev);
> + if (rval < 0)
> + goto error;
>
> - return rval;
> - } else if (!rval) {
> - rval = v4l2_ctrl_handler_setup(&sensor->pixel_array->
> - ctrl_handler);
> - if (rval)
> - return rval;
> + /* Device was already active, so don't set controls */
> + if (rval == 1)
> + return 0;
>
> - return v4l2_ctrl_handler_setup(&sensor->src->ctrl_handler);
> - }
> + /* Restore V4L2 controls to the suspended device */
> + rval = v4l2_ctrl_handler_setup(&sensor->pixel_array->ctrl_handler);
> + if (rval)
> + goto error;
>
> + rval = v4l2_ctrl_handler_setup(&sensor->src->ctrl_handler);
> + if (rval)
> + goto error;
> +
> + /* Keep PM runtime usage_count incremented on success */
> return 0;
> +error:
> + pm_runtime_put(&client->dev);
> + return rval;
> }
>
> static int ccs_set_stream(struct v4l2_subdev *subdev, int enable)
>
>
>
>
--
Kind regards,
Sakari Ailus
