| Message ID | 1415263010-7992-2-git-send-email-k.kozlowski@samsung.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On 6 November 2014 09:36, Krzysztof Kozlowski <k.kozlowski@samsung.com> wrote: > Some drivers (e.g. bus drivers) may want to check if power.irq_safe was > called by child driver, regardless of CONFIG_PM_RUNTIME. > > An example scenario is amba/bus.c and dma/pl330.c drivers. The runtime > suspend/resume callbacks in amba bus driver act differently if irq_safe > was set by child driver (in irq_safe mode bus clock is only disabled). > > The pl330 driver sets irq_safe and assumes that amba bus driver will > only disable the clock in runtime PM. So in system sleep suspend > callback the pl330 driver unprepares the clock after calling > pm_runtime_force_suspend(). > > However inconsistency would appear if CONFIG_PM_RUNTIME is not set and > child drivers do not want the irq_safe runtime PM. In such case amba bus > driver still has to know whether child driver wanted irq_safe - by > looking at dev->power.irq_safe field. > > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> FWIW: Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org> Kind regards Uffe > --- > include/linux/pm.h | 2 +- > include/linux/pm_runtime.h | 5 ++++- > 2 files changed, 5 insertions(+), 2 deletions(-) > > diff --git a/include/linux/pm.h b/include/linux/pm.h > index 383fd68aaee1..b05fa954f50d 100644 > --- a/include/linux/pm.h > +++ b/include/linux/pm.h > @@ -566,6 +566,7 @@ struct dev_pm_info { > bool ignore_children:1; > bool early_init:1; /* Owned by the PM core */ > bool direct_complete:1; /* Owned by the PM core */ > + unsigned int irq_safe:1; /* PM runtime */ > spinlock_t lock; > #ifdef CONFIG_PM_SLEEP > struct list_head entry; > @@ -590,7 +591,6 @@ struct dev_pm_info { > unsigned int run_wake:1; > unsigned int runtime_auto:1; > unsigned int no_callbacks:1; > - unsigned int irq_safe:1; > unsigned int use_autosuspend:1; > unsigned int timer_autosuspends:1; > unsigned int memalloc_noio:1; > diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h > index 367f49b9a1c9..d94a65662a60 100644 > --- a/include/linux/pm_runtime.h > +++ b/include/linux/pm_runtime.h > @@ -166,7 +166,10 @@ static inline bool pm_runtime_suspended_if_enabled(struct device *dev) { return > static inline bool pm_runtime_enabled(struct device *dev) { return false; } > > static inline void pm_runtime_no_callbacks(struct device *dev) {} > -static inline void pm_runtime_irq_safe(struct device *dev) {} > +static inline void pm_runtime_irq_safe(struct device *dev) > +{ > + dev->power.irq_safe = 1; > +} > > static inline bool pm_runtime_callbacks_present(struct device *dev) { return false; } > static inline void pm_runtime_mark_last_busy(struct device *dev) {} > -- > 1.9.1 > -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thursday, November 06, 2014 09:36:46 AM Krzysztof Kozlowski wrote: > Some drivers (e.g. bus drivers) may want to check if power.irq_safe was > called by child driver, regardless of CONFIG_PM_RUNTIME. > > An example scenario is amba/bus.c and dma/pl330.c drivers. The runtime > suspend/resume callbacks in amba bus driver act differently if irq_safe > was set by child driver (in irq_safe mode bus clock is only disabled). > > The pl330 driver sets irq_safe and assumes that amba bus driver will > only disable the clock in runtime PM. So in system sleep suspend > callback the pl330 driver unprepares the clock after calling > pm_runtime_force_suspend(). > > However inconsistency would appear if CONFIG_PM_RUNTIME is not set and > child drivers do not want the irq_safe runtime PM. In such case amba bus > driver still has to know whether child driver wanted irq_safe - by > looking at dev->power.irq_safe field. > > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> > --- > include/linux/pm.h | 2 +- > include/linux/pm_runtime.h | 5 ++++- > 2 files changed, 5 insertions(+), 2 deletions(-) > > diff --git a/include/linux/pm.h b/include/linux/pm.h > index 383fd68aaee1..b05fa954f50d 100644 > --- a/include/linux/pm.h > +++ b/include/linux/pm.h > @@ -566,6 +566,7 @@ struct dev_pm_info { > bool ignore_children:1; > bool early_init:1; /* Owned by the PM core */ > bool direct_complete:1; /* Owned by the PM core */ > + unsigned int irq_safe:1; /* PM runtime */ > spinlock_t lock; > #ifdef CONFIG_PM_SLEEP > struct list_head entry; > @@ -590,7 +591,6 @@ struct dev_pm_info { > unsigned int run_wake:1; > unsigned int runtime_auto:1; > unsigned int no_callbacks:1; > - unsigned int irq_safe:1; > unsigned int use_autosuspend:1; > unsigned int timer_autosuspends:1; > unsigned int memalloc_noio:1; Well, that is a good reason to introduce a wrapper around power.irq_safe in my view. And define the wrapper so that it always returns false for CONFIG_PM_RUNTIME unset. This way not only you wouldn't need to move the flag from under the #ifdef, but also you would make the compiler skip the relevant pieces of code entiretly for CONFIG_PM_RUNTIME unset. > diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h > index 367f49b9a1c9..d94a65662a60 100644 > --- a/include/linux/pm_runtime.h > +++ b/include/linux/pm_runtime.h > @@ -166,7 +166,10 @@ static inline bool pm_runtime_suspended_if_enabled(struct device *dev) { return > static inline bool pm_runtime_enabled(struct device *dev) { return false; } > > static inline void pm_runtime_no_callbacks(struct device *dev) {} > -static inline void pm_runtime_irq_safe(struct device *dev) {} > +static inline void pm_runtime_irq_safe(struct device *dev) > +{ > + dev->power.irq_safe = 1; > +} > > static inline bool pm_runtime_callbacks_present(struct device *dev) { return false; } > static inline void pm_runtime_mark_last_busy(struct device *dev) {} >
On czw, 2014-11-06 at 23:51 +0100, Rafael J. Wysocki wrote: > On Thursday, November 06, 2014 09:36:46 AM Krzysztof Kozlowski wrote: > > Some drivers (e.g. bus drivers) may want to check if power.irq_safe was > > called by child driver, regardless of CONFIG_PM_RUNTIME. > > > > An example scenario is amba/bus.c and dma/pl330.c drivers. The runtime > > suspend/resume callbacks in amba bus driver act differently if irq_safe > > was set by child driver (in irq_safe mode bus clock is only disabled). > > > > The pl330 driver sets irq_safe and assumes that amba bus driver will > > only disable the clock in runtime PM. So in system sleep suspend > > callback the pl330 driver unprepares the clock after calling > > pm_runtime_force_suspend(). > > > > However inconsistency would appear if CONFIG_PM_RUNTIME is not set and > > child drivers do not want the irq_safe runtime PM. In such case amba bus > > driver still has to know whether child driver wanted irq_safe - by > > looking at dev->power.irq_safe field. > > > > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> > > --- > > include/linux/pm.h | 2 +- > > include/linux/pm_runtime.h | 5 ++++- > > 2 files changed, 5 insertions(+), 2 deletions(-) > > > > diff --git a/include/linux/pm.h b/include/linux/pm.h > > index 383fd68aaee1..b05fa954f50d 100644 > > --- a/include/linux/pm.h > > +++ b/include/linux/pm.h > > @@ -566,6 +566,7 @@ struct dev_pm_info { > > bool ignore_children:1; > > bool early_init:1; /* Owned by the PM core */ > > bool direct_complete:1; /* Owned by the PM core */ > > + unsigned int irq_safe:1; /* PM runtime */ > > spinlock_t lock; > > #ifdef CONFIG_PM_SLEEP > > struct list_head entry; > > @@ -590,7 +591,6 @@ struct dev_pm_info { > > unsigned int run_wake:1; > > unsigned int runtime_auto:1; > > unsigned int no_callbacks:1; > > - unsigned int irq_safe:1; > > unsigned int use_autosuspend:1; > > unsigned int timer_autosuspends:1; > > unsigned int memalloc_noio:1; > > Well, that is a good reason to introduce a wrapper around power.irq_safe in my > view. > > And define the wrapper so that it always returns false for CONFIG_PM_RUNTIME > unset. > > This way not only you wouldn't need to move the flag from under the #ifdef, > but also you would make the compiler skip the relevant pieces of code > entiretly for CONFIG_PM_RUNTIME unset. Few days ago I would be happy with your opinion :), but know I think this is better solution than wrapper. Consider case: 1. PM_RUNTIME unset. 2. System suspends. 3. The pl330 in its suspend callback calls force_runtime_suspend which leads us to amba/bus. 4. The amba/bus.c in runtime suspend checks for irq_safe (it is FALSE), so it disables and unprepares the clock. 5. The pl330 in probe requested irq_safe so it assumes amba/bus will only disable the clock. So the pl330 unprepares the clock. Again. Best regards, Krzysztof -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, 7 Nov 2014, Krzysztof Kozlowski wrote: > > Well, that is a good reason to introduce a wrapper around power.irq_safe in my > > view. > > > > And define the wrapper so that it always returns false for CONFIG_PM_RUNTIME > > unset. > > > > This way not only you wouldn't need to move the flag from under the #ifdef, > > but also you would make the compiler skip the relevant pieces of code > > entiretly for CONFIG_PM_RUNTIME unset. > > Few days ago I would be happy with your opinion :), but know I think > this is better solution than wrapper. Consider case: > 1. PM_RUNTIME unset. > 2. System suspends. > 3. The pl330 in its suspend callback calls force_runtime_suspend which > leads us to amba/bus. > 4. The amba/bus.c in runtime suspend checks for irq_safe (it is FALSE), > so it disables and unprepares the clock. > 5. The pl330 in probe requested irq_safe so it assumes amba/bus will > only disable the clock. So the pl330 unprepares the clock. Again. To me, this sounds like a good reason to avoid using force_runtime_suspend(). In fact, it sounds like a good reason to avoid relying on the runtime PM mechanism to handle non-runtime-PM things (like a system suspend callback). If CONFIG_PM_RUNTIME isn't enabled then the runtime PM stack simply should not be used. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Friday, November 07, 2014 09:50:58 AM Alan Stern wrote: > On Fri, 7 Nov 2014, Krzysztof Kozlowski wrote: > > > > Well, that is a good reason to introduce a wrapper around power.irq_safe in my > > > view. > > > > > > And define the wrapper so that it always returns false for CONFIG_PM_RUNTIME > > > unset. > > > > > > This way not only you wouldn't need to move the flag from under the #ifdef, > > > but also you would make the compiler skip the relevant pieces of code > > > entiretly for CONFIG_PM_RUNTIME unset. > > > > Few days ago I would be happy with your opinion :), but know I think > > this is better solution than wrapper. Consider case: > > 1. PM_RUNTIME unset. > > 2. System suspends. > > 3. The pl330 in its suspend callback calls force_runtime_suspend which > > leads us to amba/bus. > > 4. The amba/bus.c in runtime suspend checks for irq_safe (it is FALSE), > > so it disables and unprepares the clock. > > 5. The pl330 in probe requested irq_safe so it assumes amba/bus will > > only disable the clock. So the pl330 unprepares the clock. Again. > > To me, this sounds like a good reason to avoid using > force_runtime_suspend(). In fact, it sounds like a good reason to > avoid relying on the runtime PM mechanism to handle non-runtime-PM > things (like a system suspend callback). If CONFIG_PM_RUNTIME isn't > enabled then the runtime PM stack simply should not be used. Amen. -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 7 November 2014 09:06, Krzysztof Kozlowski <k.kozlowski@samsung.com> wrote: > On czw, 2014-11-06 at 23:51 +0100, Rafael J. Wysocki wrote: >> On Thursday, November 06, 2014 09:36:46 AM Krzysztof Kozlowski wrote: >> > Some drivers (e.g. bus drivers) may want to check if power.irq_safe was >> > called by child driver, regardless of CONFIG_PM_RUNTIME. >> > >> > An example scenario is amba/bus.c and dma/pl330.c drivers. The runtime >> > suspend/resume callbacks in amba bus driver act differently if irq_safe >> > was set by child driver (in irq_safe mode bus clock is only disabled). >> > >> > The pl330 driver sets irq_safe and assumes that amba bus driver will >> > only disable the clock in runtime PM. So in system sleep suspend >> > callback the pl330 driver unprepares the clock after calling >> > pm_runtime_force_suspend(). >> > >> > However inconsistency would appear if CONFIG_PM_RUNTIME is not set and >> > child drivers do not want the irq_safe runtime PM. In such case amba bus >> > driver still has to know whether child driver wanted irq_safe - by >> > looking at dev->power.irq_safe field. >> > >> > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> >> > --- >> > include/linux/pm.h | 2 +- >> > include/linux/pm_runtime.h | 5 ++++- >> > 2 files changed, 5 insertions(+), 2 deletions(-) >> > >> > diff --git a/include/linux/pm.h b/include/linux/pm.h >> > index 383fd68aaee1..b05fa954f50d 100644 >> > --- a/include/linux/pm.h >> > +++ b/include/linux/pm.h >> > @@ -566,6 +566,7 @@ struct dev_pm_info { >> > bool ignore_children:1; >> > bool early_init:1; /* Owned by the PM core */ >> > bool direct_complete:1; /* Owned by the PM core */ >> > + unsigned int irq_safe:1; /* PM runtime */ >> > spinlock_t lock; >> > #ifdef CONFIG_PM_SLEEP >> > struct list_head entry; >> > @@ -590,7 +591,6 @@ struct dev_pm_info { >> > unsigned int run_wake:1; >> > unsigned int runtime_auto:1; >> > unsigned int no_callbacks:1; >> > - unsigned int irq_safe:1; >> > unsigned int use_autosuspend:1; >> > unsigned int timer_autosuspends:1; >> > unsigned int memalloc_noio:1; >> >> Well, that is a good reason to introduce a wrapper around power.irq_safe in my >> view. >> >> And define the wrapper so that it always returns false for CONFIG_PM_RUNTIME >> unset. >> >> This way not only you wouldn't need to move the flag from under the #ifdef, >> but also you would make the compiler skip the relevant pieces of code >> entiretly for CONFIG_PM_RUNTIME unset. > > Few days ago I would be happy with your opinion :), but know I think > this is better solution than wrapper. Consider case: > 1. PM_RUNTIME unset. > 2. System suspends. > 3. The pl330 in its suspend callback calls force_runtime_suspend which > leads us to amba/bus. > 4. The amba/bus.c in runtime suspend checks for irq_safe (it is FALSE), > so it disables and unprepares the clock. > 5. The pl330 in probe requested irq_safe so it assumes amba/bus will > only disable the clock. So the pl330 unprepares the clock. Again. This is easy to solve, still by using Rafael's approach. In the pl330 system PM callbacks, you need to check "pm_runtime_is_irqsafe()" or whatever the wrapper would be called. When it returns true, that's when you should do clk_prepare|unprepare(). I think that would be quite nice. Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 7 November 2014 15:50, Alan Stern <stern@rowland.harvard.edu> wrote: > On Fri, 7 Nov 2014, Krzysztof Kozlowski wrote: > >> > Well, that is a good reason to introduce a wrapper around power.irq_safe in my >> > view. >> > >> > And define the wrapper so that it always returns false for CONFIG_PM_RUNTIME >> > unset. >> > >> > This way not only you wouldn't need to move the flag from under the #ifdef, >> > but also you would make the compiler skip the relevant pieces of code >> > entiretly for CONFIG_PM_RUNTIME unset. >> >> Few days ago I would be happy with your opinion :), but know I think >> this is better solution than wrapper. Consider case: >> 1. PM_RUNTIME unset. >> 2. System suspends. >> 3. The pl330 in its suspend callback calls force_runtime_suspend which >> leads us to amba/bus. >> 4. The amba/bus.c in runtime suspend checks for irq_safe (it is FALSE), >> so it disables and unprepares the clock. >> 5. The pl330 in probe requested irq_safe so it assumes amba/bus will >> only disable the clock. So the pl330 unprepares the clock. Again. > > To me, this sounds like a good reason to avoid using > force_runtime_suspend(). In fact, it sounds like a good reason to > avoid relying on the runtime PM mechanism to handle non-runtime-PM > things (like a system suspend callback). If CONFIG_PM_RUNTIME isn't > enabled then the runtime PM stack simply should not be used. There are an important advantage of using the pm_runtime_force_suspend() here. For the driver to handle clock gating at system PM suspend, it first needs to bring the device into full power, through pm_runtime_get_sync(). Otherwise it's not safe to gate the clock, since it may already be gated. Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 10 Nov 2014, Ulf Hansson wrote: > > To me, this sounds like a good reason to avoid using > > force_runtime_suspend(). In fact, it sounds like a good reason to > > avoid relying on the runtime PM mechanism to handle non-runtime-PM > > things (like a system suspend callback). If CONFIG_PM_RUNTIME isn't > > enabled then the runtime PM stack simply should not be used. > > There are an important advantage of using the pm_runtime_force_suspend() here. > > For the driver to handle clock gating at system PM suspend, it first > needs to bring the device into full power, through > pm_runtime_get_sync(). Otherwise it's not safe to gate the clock, > since it may already be gated. That's fine, but it has nothing to do with pm_runtime_force_suspend(). Besides, if the real question is whether or not to gate the clock (or in other words, has the clock already been gated), why not just store a "clock_is_gated" flag somewhere? Alan Stern -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 10 November 2014 17:36, Alan Stern <stern@rowland.harvard.edu> wrote: > On Mon, 10 Nov 2014, Ulf Hansson wrote: > >> > To me, this sounds like a good reason to avoid using >> > force_runtime_suspend(). In fact, it sounds like a good reason to >> > avoid relying on the runtime PM mechanism to handle non-runtime-PM >> > things (like a system suspend callback). If CONFIG_PM_RUNTIME isn't >> > enabled then the runtime PM stack simply should not be used. >> >> There are an important advantage of using the pm_runtime_force_suspend() here. >> >> For the driver to handle clock gating at system PM suspend, it first >> needs to bring the device into full power, through >> pm_runtime_get_sync(). Otherwise it's not safe to gate the clock, >> since it may already be gated. > > That's fine, but it has nothing to do with pm_runtime_force_suspend(). > > Besides, if the real question is whether or not to gate the clock (or > in other words, has the clock already been gated), why not just store a > "clock_is_gated" flag somewhere? You could do that, but it's easier to not. You will need to update the runtime PM status and disable runtime PM anyway, done by the API. Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/linux/pm.h b/include/linux/pm.h index 383fd68aaee1..b05fa954f50d 100644 --- a/include/linux/pm.h +++ b/include/linux/pm.h @@ -566,6 +566,7 @@ struct dev_pm_info { bool ignore_children:1; bool early_init:1; /* Owned by the PM core */ bool direct_complete:1; /* Owned by the PM core */ + unsigned int irq_safe:1; /* PM runtime */ spinlock_t lock; #ifdef CONFIG_PM_SLEEP struct list_head entry; @@ -590,7 +591,6 @@ struct dev_pm_info { unsigned int run_wake:1; unsigned int runtime_auto:1; unsigned int no_callbacks:1; - unsigned int irq_safe:1; unsigned int use_autosuspend:1; unsigned int timer_autosuspends:1; unsigned int memalloc_noio:1; diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h index 367f49b9a1c9..d94a65662a60 100644 --- a/include/linux/pm_runtime.h +++ b/include/linux/pm_runtime.h @@ -166,7 +166,10 @@ static inline bool pm_runtime_suspended_if_enabled(struct device *dev) { return static inline bool pm_runtime_enabled(struct device *dev) { return false; } static inline void pm_runtime_no_callbacks(struct device *dev) {} -static inline void pm_runtime_irq_safe(struct device *dev) {} +static inline void pm_runtime_irq_safe(struct device *dev) +{ + dev->power.irq_safe = 1; +} static inline bool pm_runtime_callbacks_present(struct device *dev) { return false; } static inline void pm_runtime_mark_last_busy(struct device *dev) {}
Some drivers (e.g. bus drivers) may want to check if power.irq_safe was called by child driver, regardless of CONFIG_PM_RUNTIME. An example scenario is amba/bus.c and dma/pl330.c drivers. The runtime suspend/resume callbacks in amba bus driver act differently if irq_safe was set by child driver (in irq_safe mode bus clock is only disabled). The pl330 driver sets irq_safe and assumes that amba bus driver will only disable the clock in runtime PM. So in system sleep suspend callback the pl330 driver unprepares the clock after calling pm_runtime_force_suspend(). However inconsistency would appear if CONFIG_PM_RUNTIME is not set and child drivers do not want the irq_safe runtime PM. In such case amba bus driver still has to know whether child driver wanted irq_safe - by looking at dev->power.irq_safe field. Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> --- include/linux/pm.h | 2 +- include/linux/pm_runtime.h | 5 ++++- 2 files changed, 5 insertions(+), 2 deletions(-)