diff mbox series

[6/9] PM / ACPI: Provide option to disable direct_complete for ACPI devices

Message ID 1498072888-14782-7-git-send-email-ulf.hansson@linaro.org
State Superseded
Headers show
Series PM / ACPI / i2c: Fix system suspend and deploy runtime PM centric path for ACPI | expand

Commit Message

Ulf Hansson June 21, 2017, 7:21 p.m. UTC 
In some cases a driver for an ACPI device needs to be able to prevent the
ACPI PM domain from using the direct_complete path during system sleep.

One typical case is when the driver for the device needs its device to stay
runtime enabled, during the __device_suspend phase. This isn't the case
when the direct_complete path is being executed by the PM core, as it then
disables runtime PM for the device in __device_suspend(). Any following
attempts to runtime resume the device after that point, just fails.

A workaround to this problem is to let the driver runtime resume its device
from its ->prepare() callback, as that would prevent the direct_complete
path from being executed. However, that may often be a waste, especially if
it turned out that no one really needed the device.

For this reason, invent acpi_dev_disable|enable_direct_complete(), to allow
drivers to inform the ACPI PM domain to change its default behaviour during
system sleep, and thus control whether it may use the direct_complete path
or not.

Typically a driver should call acpi_dev_disable_direct_comlete() during
->probe() and acpi_dev_enable_direct_complete() in ->remove().

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

---
 drivers/acpi/device_pm.c | 37 ++++++++++++++++++++++++++++++++++++-
 include/acpi/acpi_bus.h  |  1 +
 include/linux/acpi.h     |  4 ++++
 3 files changed, 41 insertions(+), 1 deletion(-)

-- 
2.7.4

Comments

Rafael J. Wysocki June 21, 2017, 9:42 p.m. UTC | #1 
On Wed, Jun 21, 2017 at 9:21 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> In some cases a driver for an ACPI device needs to be able to prevent the

> ACPI PM domain from using the direct_complete path during system sleep.

>

> One typical case is when the driver for the device needs its device to stay

> runtime enabled, during the __device_suspend phase. This isn't the case

> when the direct_complete path is being executed by the PM core, as it then

> disables runtime PM for the device in __device_suspend(). Any following

> attempts to runtime resume the device after that point, just fails.

>

> A workaround to this problem is to let the driver runtime resume its device

> from its ->prepare() callback, as that would prevent the direct_complete

> path from being executed. However, that may often be a waste, especially if

> it turned out that no one really needed the device.

>

> For this reason, invent acpi_dev_disable|enable_direct_complete(), to allow

> drivers to inform the ACPI PM domain to change its default behaviour during

> system sleep, and thus control whether it may use the direct_complete path

> or not.

>

> Typically a driver should call acpi_dev_disable_direct_comlete() during

> ->probe() and acpi_dev_enable_direct_complete() in ->remove().

>

> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

> ---

>  drivers/acpi/device_pm.c | 37 ++++++++++++++++++++++++++++++++++++-

>  include/acpi/acpi_bus.h  |  1 +

>  include/linux/acpi.h     |  4 ++++

>  3 files changed, 41 insertions(+), 1 deletion(-)

>

> diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c

> index ee51e75..2393a1a 100644

> --- a/drivers/acpi/device_pm.c

> +++ b/drivers/acpi/device_pm.c

> @@ -879,6 +879,41 @@ EXPORT_SYMBOL_GPL(acpi_subsys_runtime_resume);

>

>  #ifdef CONFIG_PM_SLEEP

>  /**

> + * acpi_dev_disable_direct_complete - Disable the direct_complete path for ACPI.

> + * @dev: Device to disable the path for.

> + *

> + * Per default the ACPI PM domain tries to use the direct_complete path for its

> + * devices during system sleep. This function allows a user, typically a driver

> + * during probe, to disable the direct_complete path from being used by ACPI.

> + */

> +void acpi_dev_disable_direct_complete(struct device *dev)

> +{

> +       struct acpi_device *adev = ACPI_COMPANION(dev);

> +

> +       if (adev)

> +               adev->no_direct_complete = true;


We have an analogous flag in PCI now and it is called needs_resume, so
it would be good to be consistent with that.

> +}

> +EXPORT_SYMBOL_GPL(acpi_dev_disable_direct_complete);

> +

> +/**

> + * acpi_dev_enable_direct_complete - Enable the direct_complete path for ACPI.

> + * @dev: Device to enable the path for.

> + *

> + * Enable the direct_complete path to be used during system suspend for the ACPI

> + * PM domain, which is the default option. Typically a driver that disabled the

> + * path during ->probe(), must call this function during ->remove() to re-enable

> + * the direct_complete path to be used by ACPI.

> + */

> +void acpi_dev_enable_direct_complete(struct device *dev)

> +{

> +       struct acpi_device *adev = ACPI_COMPANION(dev);

> +

> +       if (adev)

> +               adev->no_direct_complete = false;

> +}

> +EXPORT_SYMBOL_GPL(acpi_dev_enable_direct_complete);

> +

> +/**

>   * acpi_dev_suspend_late - Put device into a low-power state using ACPI.

>   * @dev: Device to put into a low-power state.

>   *

> @@ -967,7 +1002,7 @@ int acpi_subsys_prepare(struct device *dev)

>         if (ret < 0)

>                 return ret;

>

> -       if (!adev || !pm_runtime_suspended(dev))

> +       if (!adev || adev->no_direct_complete || !pm_runtime_suspended(dev))

>                 return 0;

>

>         return !acpi_dev_needs_resume(dev, adev);

> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h

> index 63a90a6..2293d24 100644

> --- a/include/acpi/acpi_bus.h

> +++ b/include/acpi/acpi_bus.h

> @@ -380,6 +380,7 @@ struct acpi_device {

>         struct list_head physical_node_list;

>         struct mutex physical_node_lock;

>         void (*remove)(struct acpi_device *);

> +       bool no_direct_complete;


Also what about adding this to struct acpi_device_power instead?

Thanks,
Rafael
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Ulf Hansson June 22, 2017, 9:35 a.m. UTC | #2 
On 21 June 2017 at 23:42, Rafael J. Wysocki <rafael@kernel.org> wrote:
> On Wed, Jun 21, 2017 at 9:21 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:

>> In some cases a driver for an ACPI device needs to be able to prevent the

>> ACPI PM domain from using the direct_complete path during system sleep.

>>

>> One typical case is when the driver for the device needs its device to stay

>> runtime enabled, during the __device_suspend phase. This isn't the case

>> when the direct_complete path is being executed by the PM core, as it then

>> disables runtime PM for the device in __device_suspend(). Any following

>> attempts to runtime resume the device after that point, just fails.

>>

>> A workaround to this problem is to let the driver runtime resume its device

>> from its ->prepare() callback, as that would prevent the direct_complete

>> path from being executed. However, that may often be a waste, especially if

>> it turned out that no one really needed the device.

>>

>> For this reason, invent acpi_dev_disable|enable_direct_complete(), to allow

>> drivers to inform the ACPI PM domain to change its default behaviour during

>> system sleep, and thus control whether it may use the direct_complete path

>> or not.

>>

>> Typically a driver should call acpi_dev_disable_direct_comlete() during

>> ->probe() and acpi_dev_enable_direct_complete() in ->remove().

>>

>> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

>> ---

>>  drivers/acpi/device_pm.c | 37 ++++++++++++++++++++++++++++++++++++-

>>  include/acpi/acpi_bus.h  |  1 +

>>  include/linux/acpi.h     |  4 ++++

>>  3 files changed, 41 insertions(+), 1 deletion(-)

>>

>> diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c

>> index ee51e75..2393a1a 100644

>> --- a/drivers/acpi/device_pm.c

>> +++ b/drivers/acpi/device_pm.c

>> @@ -879,6 +879,41 @@ EXPORT_SYMBOL_GPL(acpi_subsys_runtime_resume);

>>

>>  #ifdef CONFIG_PM_SLEEP

>>  /**

>> + * acpi_dev_disable_direct_complete - Disable the direct_complete path for ACPI.

>> + * @dev: Device to disable the path for.

>> + *

>> + * Per default the ACPI PM domain tries to use the direct_complete path for its

>> + * devices during system sleep. This function allows a user, typically a driver

>> + * during probe, to disable the direct_complete path from being used by ACPI.

>> + */

>> +void acpi_dev_disable_direct_complete(struct device *dev)

>> +{

>> +       struct acpi_device *adev = ACPI_COMPANION(dev);

>> +

>> +       if (adev)

>> +               adev->no_direct_complete = true;

>

> We have an analogous flag in PCI now and it is called needs_resume, so

> it would be good to be consistent with that.


I was trying to come up with a nice name, however I couldn't find
anything better than no_direct_complete.

However as the next patch somewhat, extends the flag to also be use
for the runtime PM centric path, I should perhaps choose something
more related to that?

I think make "needs_resume" is going to e bit confusing, especially
while extending the usage for the flag it in the next patch, no?

>

>> +}

>> +EXPORT_SYMBOL_GPL(acpi_dev_disable_direct_complete);

>> +

>> +/**

>> + * acpi_dev_enable_direct_complete - Enable the direct_complete path for ACPI.

>> + * @dev: Device to enable the path for.

>> + *

>> + * Enable the direct_complete path to be used during system suspend for the ACPI

>> + * PM domain, which is the default option. Typically a driver that disabled the

>> + * path during ->probe(), must call this function during ->remove() to re-enable

>> + * the direct_complete path to be used by ACPI.

>> + */

>> +void acpi_dev_enable_direct_complete(struct device *dev)

>> +{

>> +       struct acpi_device *adev = ACPI_COMPANION(dev);

>> +

>> +       if (adev)

>> +               adev->no_direct_complete = false;

>> +}

>> +EXPORT_SYMBOL_GPL(acpi_dev_enable_direct_complete);

>> +

>> +/**

>>   * acpi_dev_suspend_late - Put device into a low-power state using ACPI.

>>   * @dev: Device to put into a low-power state.

>>   *

>> @@ -967,7 +1002,7 @@ int acpi_subsys_prepare(struct device *dev)

>>         if (ret < 0)

>>                 return ret;

>>

>> -       if (!adev || !pm_runtime_suspended(dev))

>> +       if (!adev || adev->no_direct_complete || !pm_runtime_suspended(dev))

>>                 return 0;

>>

>>         return !acpi_dev_needs_resume(dev, adev);

>> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h

>> index 63a90a6..2293d24 100644

>> --- a/include/acpi/acpi_bus.h

>> +++ b/include/acpi/acpi_bus.h

>> @@ -380,6 +380,7 @@ struct acpi_device {

>>         struct list_head physical_node_list;

>>         struct mutex physical_node_lock;

>>         void (*remove)(struct acpi_device *);

>> +       bool no_direct_complete;

>

> Also what about adding this to struct acpi_device_power instead?


Yes, thanks for the suggestion!

>

> Thanks,

> Rafael


Kind regards
Uffe
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Rafael J. Wysocki June 22, 2017, 2:38 p.m. UTC | #3 
On Thursday, June 22, 2017 11:35:35 AM Ulf Hansson wrote:
> On 21 June 2017 at 23:42, Rafael J. Wysocki <rafael@kernel.org> wrote:

> > On Wed, Jun 21, 2017 at 9:21 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:

> >> In some cases a driver for an ACPI device needs to be able to prevent the

> >> ACPI PM domain from using the direct_complete path during system sleep.

> >>

> >> One typical case is when the driver for the device needs its device to stay

> >> runtime enabled, during the __device_suspend phase. This isn't the case

> >> when the direct_complete path is being executed by the PM core, as it then

> >> disables runtime PM for the device in __device_suspend(). Any following

> >> attempts to runtime resume the device after that point, just fails.

> >>

> >> A workaround to this problem is to let the driver runtime resume its device

> >> from its ->prepare() callback, as that would prevent the direct_complete

> >> path from being executed. However, that may often be a waste, especially if

> >> it turned out that no one really needed the device.

> >>

> >> For this reason, invent acpi_dev_disable|enable_direct_complete(), to allow

> >> drivers to inform the ACPI PM domain to change its default behaviour during

> >> system sleep, and thus control whether it may use the direct_complete path

> >> or not.

> >>

> >> Typically a driver should call acpi_dev_disable_direct_comlete() during

> >> ->probe() and acpi_dev_enable_direct_complete() in ->remove().

> >>

> >> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

> >> ---

> >>  drivers/acpi/device_pm.c | 37 ++++++++++++++++++++++++++++++++++++-

> >>  include/acpi/acpi_bus.h  |  1 +

> >>  include/linux/acpi.h     |  4 ++++

> >>  3 files changed, 41 insertions(+), 1 deletion(-)

> >>

> >> diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c

> >> index ee51e75..2393a1a 100644

> >> --- a/drivers/acpi/device_pm.c

> >> +++ b/drivers/acpi/device_pm.c

> >> @@ -879,6 +879,41 @@ EXPORT_SYMBOL_GPL(acpi_subsys_runtime_resume);

> >>

> >>  #ifdef CONFIG_PM_SLEEP

> >>  /**

> >> + * acpi_dev_disable_direct_complete - Disable the direct_complete path for ACPI.

> >> + * @dev: Device to disable the path for.

> >> + *

> >> + * Per default the ACPI PM domain tries to use the direct_complete path for its

> >> + * devices during system sleep. This function allows a user, typically a driver

> >> + * during probe, to disable the direct_complete path from being used by ACPI.

> >> + */

> >> +void acpi_dev_disable_direct_complete(struct device *dev)

> >> +{

> >> +       struct acpi_device *adev = ACPI_COMPANION(dev);

> >> +

> >> +       if (adev)

> >> +               adev->no_direct_complete = true;

> >

> > We have an analogous flag in PCI now and it is called needs_resume, so

> > it would be good to be consistent with that.

> 

> I was trying to come up with a nice name, however I couldn't find

> anything better than no_direct_complete.

> 

> However as the next patch somewhat, extends the flag to also be use

> for the runtime PM centric path, I should perhaps choose something

> more related to that?

> 

> I think make "needs_resume" is going to e bit confusing, especially

> while extending the usage for the flag it in the next patch, no?


OK, fair enough, but I still think the name isn't really nice. :-)

In fact, I'm not sure if the new flag is necessary at all.

If the driver is expected to use pm_runtime_force_suspend|resume() along with
it every time, why not to make the ACPI PM domain code check if the driver's
callback pointers point to pm_runtime_force_suspend|resume() and work
accordingly?

Thanks,
Rafael

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Rafael J. Wysocki June 22, 2017, 9:33 p.m. UTC | #4 
On Thu, Jun 22, 2017 at 11:29 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> On 22 June 2017 at 16:38, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:

>> On Thursday, June 22, 2017 11:35:35 AM Ulf Hansson wrote:

>>> On 21 June 2017 at 23:42, Rafael J. Wysocki <rafael@kernel.org> wrote:

>>> > On Wed, Jun 21, 2017 at 9:21 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:

>>> >> In some cases a driver for an ACPI device needs to be able to prevent the

>>> >> ACPI PM domain from using the direct_complete path during system sleep.

>>> >>

>>> >> One typical case is when the driver for the device needs its device to stay

>>> >> runtime enabled, during the __device_suspend phase. This isn't the case

>>> >> when the direct_complete path is being executed by the PM core, as it then

>>> >> disables runtime PM for the device in __device_suspend(). Any following

>>> >> attempts to runtime resume the device after that point, just fails.

>>> >>

>>> >> A workaround to this problem is to let the driver runtime resume its device

>>> >> from its ->prepare() callback, as that would prevent the direct_complete

>>> >> path from being executed. However, that may often be a waste, especially if

>>> >> it turned out that no one really needed the device.

>>> >>

>>> >> For this reason, invent acpi_dev_disable|enable_direct_complete(), to allow

>>> >> drivers to inform the ACPI PM domain to change its default behaviour during

>>> >> system sleep, and thus control whether it may use the direct_complete path

>>> >> or not.

>>> >>

>>> >> Typically a driver should call acpi_dev_disable_direct_comlete() during

>>> >> ->probe() and acpi_dev_enable_direct_complete() in ->remove().

>>> >>

>>> >> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

>>> >> ---

>>> >>  drivers/acpi/device_pm.c | 37 ++++++++++++++++++++++++++++++++++++-

>>> >>  include/acpi/acpi_bus.h  |  1 +

>>> >>  include/linux/acpi.h     |  4 ++++

>>> >>  3 files changed, 41 insertions(+), 1 deletion(-)

>>> >>

>>> >> diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c

>>> >> index ee51e75..2393a1a 100644

>>> >> --- a/drivers/acpi/device_pm.c

>>> >> +++ b/drivers/acpi/device_pm.c

>>> >> @@ -879,6 +879,41 @@ EXPORT_SYMBOL_GPL(acpi_subsys_runtime_resume);

>>> >>

>>> >>  #ifdef CONFIG_PM_SLEEP

>>> >>  /**

>>> >> + * acpi_dev_disable_direct_complete - Disable the direct_complete path for ACPI.

>>> >> + * @dev: Device to disable the path for.

>>> >> + *

>>> >> + * Per default the ACPI PM domain tries to use the direct_complete path for its

>>> >> + * devices during system sleep. This function allows a user, typically a driver

>>> >> + * during probe, to disable the direct_complete path from being used by ACPI.

>>> >> + */

>>> >> +void acpi_dev_disable_direct_complete(struct device *dev)

>>> >> +{

>>> >> +       struct acpi_device *adev = ACPI_COMPANION(dev);

>>> >> +

>>> >> +       if (adev)

>>> >> +               adev->no_direct_complete = true;

>>> >

>>> > We have an analogous flag in PCI now and it is called needs_resume, so

>>> > it would be good to be consistent with that.

>>>

>>> I was trying to come up with a nice name, however I couldn't find

>>> anything better than no_direct_complete.

>>>

>>> However as the next patch somewhat, extends the flag to also be use

>>> for the runtime PM centric path, I should perhaps choose something

>>> more related to that?

>>>

>>> I think make "needs_resume" is going to e bit confusing, especially

>>> while extending the usage for the flag it in the next patch, no?

>>

>> OK, fair enough, but I still think the name isn't really nice. :-)

>

> How about use_rpm_centric_sleep or use_rpm_ops_for_sleep?

>

> :-)


no_direct_complete is better than that IMO.

>>

>> In fact, I'm not sure if the new flag is necessary at all.

>>

>> If the driver is expected to use pm_runtime_force_suspend|resume() along with

>> it every time, why not to make the ACPI PM domain code check if the driver's

>> callback pointers point to pm_runtime_force_suspend|resume() and work

>> accordingly?

>

> I get the idea, however it would limit the driver from doing other

> specific things from its sleep callbacks.

>

> It may for example deal with wakeups during system suspend, and when

> that is done, it can call pm_runtime_force_suspend() from that

> callback.


I see.

> Potentially that could be done from the runtime PM callback itself,

> (via checking pm_runtime_enabled)...


Anyway, it would be good to have a way to verify that the driver is
doing the right thing or we'll have bugs in that area and people
wondering what's up.

Thanks,
Rafael
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diff mbox series

Patch

diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index ee51e75..2393a1a 100644
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -879,6 +879,41 @@  EXPORT_SYMBOL_GPL(acpi_subsys_runtime_resume);
 
 #ifdef CONFIG_PM_SLEEP
 /**
+ * acpi_dev_disable_direct_complete - Disable the direct_complete path for ACPI.
+ * @dev: Device to disable the path for.
+ *
+ * Per default the ACPI PM domain tries to use the direct_complete path for its
+ * devices during system sleep. This function allows a user, typically a driver
+ * during probe, to disable the direct_complete path from being used by ACPI.
+ */
+void acpi_dev_disable_direct_complete(struct device *dev)
+{
+	struct acpi_device *adev = ACPI_COMPANION(dev);
+
+	if (adev)
+		adev->no_direct_complete = true;
+}
+EXPORT_SYMBOL_GPL(acpi_dev_disable_direct_complete);
+
+/**
+ * acpi_dev_enable_direct_complete - Enable the direct_complete path for ACPI.
+ * @dev: Device to enable the path for.
+ *
+ * Enable the direct_complete path to be used during system suspend for the ACPI
+ * PM domain, which is the default option. Typically a driver that disabled the
+ * path during ->probe(), must call this function during ->remove() to re-enable
+ * the direct_complete path to be used by ACPI.
+ */
+void acpi_dev_enable_direct_complete(struct device *dev)
+{
+	struct acpi_device *adev = ACPI_COMPANION(dev);
+
+	if (adev)
+		adev->no_direct_complete = false;
+}
+EXPORT_SYMBOL_GPL(acpi_dev_enable_direct_complete);
+
+/**
  * acpi_dev_suspend_late - Put device into a low-power state using ACPI.
  * @dev: Device to put into a low-power state.
  *
@@ -967,7 +1002,7 @@  int acpi_subsys_prepare(struct device *dev)
 	if (ret < 0)
 		return ret;
 
-	if (!adev || !pm_runtime_suspended(dev))
+	if (!adev || adev->no_direct_complete || !pm_runtime_suspended(dev))
 		return 0;
 
 	return !acpi_dev_needs_resume(dev, adev);
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 63a90a6..2293d24 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -380,6 +380,7 @@  struct acpi_device {
 	struct list_head physical_node_list;
 	struct mutex physical_node_lock;
 	void (*remove)(struct acpi_device *);
+	bool no_direct_complete;
 };
 
 /* Non-device subnode */
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 137e4a3..a41cca5 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -859,6 +859,8 @@  static inline int acpi_dev_pm_attach(struct device *dev, bool power_on)
 #endif
 
 #if defined(CONFIG_ACPI) && defined(CONFIG_PM_SLEEP)
+void acpi_dev_disable_direct_complete(struct device *dev);
+void acpi_dev_enable_direct_complete(struct device *dev);
 int acpi_dev_suspend_late(struct device *dev);
 int acpi_dev_resume_early(struct device *dev);
 int acpi_subsys_prepare(struct device *dev);
@@ -868,6 +870,8 @@  int acpi_subsys_resume_early(struct device *dev);
 int acpi_subsys_suspend(struct device *dev);
 int acpi_subsys_freeze(struct device *dev);
 #else
+static inline void acpi_dev_disable_direct_complete(struct device *dev) {}
+static inline void acpi_dev_enable_direct_complete(struct device *dev) {}
 static inline int acpi_dev_suspend_late(struct device *dev) { return 0; }
 static inline int acpi_dev_resume_early(struct device *dev) { return 0; }
 static inline int acpi_subsys_prepare(struct device *dev) { return 0; }