| Message ID | 20231117111433.1561669-6-sakari.ailus@linux.intel.com (mailing list archive) |
|---|---|
| State | Changes Requested, archived |
| Headers | show |
| Series | Small Runtime PM API changes | expand |
Hi Sakari On Fri, Nov 17, 2023 at 01:14:31PM +0200, Sakari Ailus wrote: > Use pm_runtime_get_if_active() to get the device's runtime PM usage_count > and set controls, then use runtime PM autosuspend once the controls have > been set (instead of likely transitioning to suspended state immediately). > > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> > --- > drivers/media/i2c/ov8858.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/drivers/media/i2c/ov8858.c b/drivers/media/i2c/ov8858.c > index 3af6125a2eee..a99b91700a8d 100644 > --- a/drivers/media/i2c/ov8858.c > +++ b/drivers/media/i2c/ov8858.c > @@ -1538,7 +1538,7 @@ static int ov8858_set_ctrl(struct v4l2_ctrl *ctrl) > struct v4l2_subdev_state *state; > u16 digi_gain; > s64 max_exp; > - int ret; > + int ret, pm_status; > > /* > * The control handler and the subdev state use the same mutex and the > @@ -1561,7 +1561,8 @@ static int ov8858_set_ctrl(struct v4l2_ctrl *ctrl) > break; > } > > - if (!pm_runtime_get_if_in_use(&client->dev)) > + pm_status = pm_runtime_get_if_active(&client->dev); > + if (!pm_status) > return 0; > > switch (ctrl->id) { > @@ -1601,7 +1602,8 @@ static int ov8858_set_ctrl(struct v4l2_ctrl *ctrl) > break; > } > > - pm_runtime_put(&client->dev); > + if (pm_status > 0) I'm not 100% sure I get this bit. If we get here it means pm_status is either -EINVAL or > 0, otherwise we would have exited earlier. What's the point of checking for > 0 here ? There are two cases where pm_status is -EINVAL, either !CONFIG_PM and the the below call is a nop, or if pm_runtime has not been enabled by the driver, which means the driver doesn't use pm_runtime at all. Are there other cases I have missed that require checking here for pm_status > 0 ? > + pm_runtime_mark_busy_autosusp(&client->dev); > > return ret; > } > -- > 2.39.2 >
Hi Jacopo, On Fri, Nov 17, 2023 at 04:30:15PM +0100, Jacopo Mondi wrote: > Hi Sakari > > On Fri, Nov 17, 2023 at 01:14:31PM +0200, Sakari Ailus wrote: > > Use pm_runtime_get_if_active() to get the device's runtime PM usage_count > > and set controls, then use runtime PM autosuspend once the controls have > > been set (instead of likely transitioning to suspended state immediately). > > > > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> > > --- > > drivers/media/i2c/ov8858.c | 8 +++++--- > > 1 file changed, 5 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/media/i2c/ov8858.c b/drivers/media/i2c/ov8858.c > > index 3af6125a2eee..a99b91700a8d 100644 > > --- a/drivers/media/i2c/ov8858.c > > +++ b/drivers/media/i2c/ov8858.c > > @@ -1538,7 +1538,7 @@ static int ov8858_set_ctrl(struct v4l2_ctrl *ctrl) > > struct v4l2_subdev_state *state; > > u16 digi_gain; > > s64 max_exp; > > - int ret; > > + int ret, pm_status; > > > > /* > > * The control handler and the subdev state use the same mutex and the > > @@ -1561,7 +1561,8 @@ static int ov8858_set_ctrl(struct v4l2_ctrl *ctrl) > > break; > > } > > > > - if (!pm_runtime_get_if_in_use(&client->dev)) > > + pm_status = pm_runtime_get_if_active(&client->dev); > > + if (!pm_status) > > return 0; > > > > switch (ctrl->id) { > > @@ -1601,7 +1602,8 @@ static int ov8858_set_ctrl(struct v4l2_ctrl *ctrl) > > break; > > } > > > > - pm_runtime_put(&client->dev); > > + if (pm_status > 0) > > I'm not 100% sure I get this bit. > > If we get here it means pm_status is either -EINVAL or > 0, otherwise > we would have exited earlier. > > What's the point of checking for > 0 here ? > > There are two cases where pm_status is -EINVAL, either !CONFIG_PM and > the the below call is a nop, or if pm_runtime has not been enabled by > the driver, which means the driver doesn't use pm_runtime at all. > > Are there other cases I have missed that require checking here for > pm_status > 0 ? Other than Runtime PM being disabled, I don't think that should happen. So as such this patch does not fix a bug. I just prefer to be extra cautious when it comes to use counts. > > > + pm_runtime_mark_busy_autosusp(&client->dev); > > > > return ret; > > }
Hi Sakari On Sat, Nov 18, 2023 at 11:12:41AM +0000, Sakari Ailus wrote: > On Fri, Nov 17, 2023 at 04:30:15PM +0100, Jacopo Mondi wrote: > > On Fri, Nov 17, 2023 at 01:14:31PM +0200, Sakari Ailus wrote: > > > Use pm_runtime_get_if_active() to get the device's runtime PM usage_count > > > and set controls, then use runtime PM autosuspend once the controls have > > > been set (instead of likely transitioning to suspended state immediately). > > > > > > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> > > > --- > > > drivers/media/i2c/ov8858.c | 8 +++++--- > > > 1 file changed, 5 insertions(+), 3 deletions(-) > > > > > > diff --git a/drivers/media/i2c/ov8858.c b/drivers/media/i2c/ov8858.c > > > index 3af6125a2eee..a99b91700a8d 100644 > > > --- a/drivers/media/i2c/ov8858.c > > > +++ b/drivers/media/i2c/ov8858.c > > > @@ -1538,7 +1538,7 @@ static int ov8858_set_ctrl(struct v4l2_ctrl *ctrl) > > > struct v4l2_subdev_state *state; > > > u16 digi_gain; > > > s64 max_exp; > > > - int ret; > > > + int ret, pm_status; > > > > > > /* > > > * The control handler and the subdev state use the same mutex and the > > > @@ -1561,7 +1561,8 @@ static int ov8858_set_ctrl(struct v4l2_ctrl *ctrl) > > > break; > > > } > > > > > > - if (!pm_runtime_get_if_in_use(&client->dev)) > > > + pm_status = pm_runtime_get_if_active(&client->dev); > > > + if (!pm_status) > > > return 0; > > > > > > switch (ctrl->id) { > > > @@ -1601,7 +1602,8 @@ static int ov8858_set_ctrl(struct v4l2_ctrl *ctrl) > > > break; > > > } > > > > > > - pm_runtime_put(&client->dev); > > > + if (pm_status > 0) > > > > I'm not 100% sure I get this bit. > > > > If we get here it means pm_status is either -EINVAL or > 0, otherwise > > we would have exited earlier. > > > > What's the point of checking for > 0 here ? > > > > There are two cases where pm_status is -EINVAL, either !CONFIG_PM and > > the the below call is a nop, or if pm_runtime has not been enabled by > > the driver, which means the driver doesn't use pm_runtime at all. > > > > Are there other cases I have missed that require checking here for > > pm_status > 0 ? > > Other than Runtime PM being disabled, I don't think that should happen. > > So as such this patch does not fix a bug. I just prefer to be extra > cautious when it comes to use counts. What happened to the old motto of "if it's not broken, don't fix it" ? :-) I like how this series (slightly) simplifies the runtime PM API by giving pm_runtime_get_if_active() the right behaviour for the most common use cases. Let's continue in that direction, and evolve the API to simplify driver, not render them more complex. I would prefer refactoring this series to first switch drivers to pm_runtime_get_if_active(), and then use autosuspend at the end of the .s_ctrl() handler. That can be two patches, each modifying all relevant sensor driver. > > > + pm_runtime_mark_busy_autosusp(&client->dev); > > > > > > return ret; > > > }
Hi Laurent, On Sat, Nov 18, 2023 at 07:33:15PM +0200, Laurent Pinchart wrote: > Hi Sakari > > On Sat, Nov 18, 2023 at 11:12:41AM +0000, Sakari Ailus wrote: > > On Fri, Nov 17, 2023 at 04:30:15PM +0100, Jacopo Mondi wrote: > > > On Fri, Nov 17, 2023 at 01:14:31PM +0200, Sakari Ailus wrote: > > > > Use pm_runtime_get_if_active() to get the device's runtime PM usage_count > > > > and set controls, then use runtime PM autosuspend once the controls have > > > > been set (instead of likely transitioning to suspended state immediately). > > > > > > > > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> > > > > --- > > > > drivers/media/i2c/ov8858.c | 8 +++++--- > > > > 1 file changed, 5 insertions(+), 3 deletions(-) > > > > > > > > diff --git a/drivers/media/i2c/ov8858.c b/drivers/media/i2c/ov8858.c > > > > index 3af6125a2eee..a99b91700a8d 100644 > > > > --- a/drivers/media/i2c/ov8858.c > > > > +++ b/drivers/media/i2c/ov8858.c > > > > @@ -1538,7 +1538,7 @@ static int ov8858_set_ctrl(struct v4l2_ctrl *ctrl) > > > > struct v4l2_subdev_state *state; > > > > u16 digi_gain; > > > > s64 max_exp; > > > > - int ret; > > > > + int ret, pm_status; > > > > > > > > /* > > > > * The control handler and the subdev state use the same mutex and the > > > > @@ -1561,7 +1561,8 @@ static int ov8858_set_ctrl(struct v4l2_ctrl *ctrl) > > > > break; > > > > } > > > > > > > > - if (!pm_runtime_get_if_in_use(&client->dev)) > > > > + pm_status = pm_runtime_get_if_active(&client->dev); > > > > + if (!pm_status) > > > > return 0; > > > > > > > > switch (ctrl->id) { > > > > @@ -1601,7 +1602,8 @@ static int ov8858_set_ctrl(struct v4l2_ctrl *ctrl) > > > > break; > > > > } > > > > > > > > - pm_runtime_put(&client->dev); > > > > + if (pm_status > 0) > > > > > > I'm not 100% sure I get this bit. > > > > > > If we get here it means pm_status is either -EINVAL or > 0, otherwise > > > we would have exited earlier. > > > > > > What's the point of checking for > 0 here ? > > > > > > There are two cases where pm_status is -EINVAL, either !CONFIG_PM and > > > the the below call is a nop, or if pm_runtime has not been enabled by > > > the driver, which means the driver doesn't use pm_runtime at all. > > > > > > Are there other cases I have missed that require checking here for > > > pm_status > 0 ? > > > > Other than Runtime PM being disabled, I don't think that should happen. > > > > So as such this patch does not fix a bug. I just prefer to be extra > > cautious when it comes to use counts. > > What happened to the old motto of "if it's not broken, don't fix it" ? People tend to take patterns used in drivers and this indeed works here, but only when taken with the rest of the Runtime PM API usage. > :-) I like how this series (slightly) simplifies the runtime PM API by > giving pm_runtime_get_if_active() the right behaviour for the most > common use cases. Let's continue in that direction, and evolve the API > to simplify driver, not render them more complex. > > I would prefer refactoring this series to first switch drivers to > pm_runtime_get_if_active(), and then use autosuspend at the end of the > .s_ctrl() handler. That can be two patches, each modifying all relevant > sensor driver. I think it should be fine to do both in the same patch indeed.
diff --git a/drivers/media/i2c/ov8858.c b/drivers/media/i2c/ov8858.c index 3af6125a2eee..a99b91700a8d 100644 --- a/drivers/media/i2c/ov8858.c +++ b/drivers/media/i2c/ov8858.c @@ -1538,7 +1538,7 @@ static int ov8858_set_ctrl(struct v4l2_ctrl *ctrl) struct v4l2_subdev_state *state; u16 digi_gain; s64 max_exp; - int ret; + int ret, pm_status; /* * The control handler and the subdev state use the same mutex and the @@ -1561,7 +1561,8 @@ static int ov8858_set_ctrl(struct v4l2_ctrl *ctrl) break; } - if (!pm_runtime_get_if_in_use(&client->dev)) + pm_status = pm_runtime_get_if_active(&client->dev); + if (!pm_status) return 0; switch (ctrl->id) { @@ -1601,7 +1602,8 @@ static int ov8858_set_ctrl(struct v4l2_ctrl *ctrl) break; } - pm_runtime_put(&client->dev); + if (pm_status > 0) + pm_runtime_mark_busy_autosusp(&client->dev); return ret; }
Use pm_runtime_get_if_active() to get the device's runtime PM usage_count and set controls, then use runtime PM autosuspend once the controls have been set (instead of likely transitioning to suspended state immediately). Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> --- drivers/media/i2c/ov8858.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)