[v5,1/2] PM / Domains: Add support for 'required-opps' to set default perf state

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  • PM / Domains: Add support for 'required-opps' to set default perf state
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Commit Message

Rajendra Nayak July 20, 2021, 7:07 a.m.
Some devices within power domains with performance states do not
support DVFS, but still need to vote on a default/static state
while they are active. They can express this using the 'required-opps'
property in device tree, which points to the phandle of the OPP
supported by the corresponding power-domains.

Add support to parse this information from DT and then set the
specified performance state during attach and drop it on detach.
runtime suspend/resume callbacks already have logic to drop/set
the vote as needed and should take care of dropping the default
perf state vote on runtime suspend and restore it back on runtime
resume.

Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
---
 drivers/base/power/domain.c | 28 +++++++++++++++++++++++++---
 include/linux/pm_domain.h   |  1 +
 2 files changed, 26 insertions(+), 3 deletions(-)

Comments

Felipe Balbi July 20, 2021, 7:18 a.m. | #1
Hi,

Rajendra Nayak <rnayak@codeaurora.org> writes:
> @@ -2635,9 +2641,10 @@ static void genpd_dev_pm_sync(struct device *dev)
>  static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
>  				 unsigned int index, bool power_on)
>  {
> +	struct device_node *np;
>  	struct of_phandle_args pd_args;
>  	struct generic_pm_domain *pd;
> -	int ret;
> +	int ret, pstate;

nit: might want to keep one variable declaration per line here.
Ulf Hansson Aug. 2, 2021, 12:59 p.m. | #2
On Tue, 20 Jul 2021 at 09:12, Rajendra Nayak <rnayak@codeaurora.org> wrote:
>
> Some devices within power domains with performance states do not
> support DVFS, but still need to vote on a default/static state
> while they are active. They can express this using the 'required-opps'
> property in device tree, which points to the phandle of the OPP
> supported by the corresponding power-domains.
>
> Add support to parse this information from DT and then set the
> specified performance state during attach and drop it on detach.
> runtime suspend/resume callbacks already have logic to drop/set
> the vote as needed and should take care of dropping the default
> perf state vote on runtime suspend and restore it back on runtime
> resume.
>
> Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
> ---
>  drivers/base/power/domain.c | 28 +++++++++++++++++++++++++---
>  include/linux/pm_domain.h   |  1 +
>  2 files changed, 26 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index a934c67..f454031 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2598,6 +2598,12 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off)
>
>         dev_dbg(dev, "removing from PM domain %s\n", pd->name);
>
> +       /* Drop the default performance state */
> +       if (dev_gpd_data(dev)->default_pstate) {
> +               dev_pm_genpd_set_performance_state(dev, 0);
> +               dev_gpd_data(dev)->default_pstate = 0;
> +       }
> +
>         for (i = 1; i < GENPD_RETRY_MAX_MS; i <<= 1) {
>                 ret = genpd_remove_device(pd, dev);
>                 if (ret != -EAGAIN)
> @@ -2635,9 +2641,10 @@ static void genpd_dev_pm_sync(struct device *dev)
>  static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
>                                  unsigned int index, bool power_on)
>  {
> +       struct device_node *np;
>         struct of_phandle_args pd_args;
>         struct generic_pm_domain *pd;
> -       int ret;
> +       int ret, pstate;
>
>         ret = of_parse_phandle_with_args(dev->of_node, "power-domains",
>                                 "#power-domain-cells", index, &pd_args);
> @@ -2675,10 +2682,25 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
>                 genpd_unlock(pd);
>         }
>
> -       if (ret)
> +       if (ret) {
>                 genpd_remove_device(pd, dev);
> +               return -EPROBE_DEFER;
> +       }
> +
> +       /* Set the default performance state */
> +       np = base_dev->of_node;

Please use dev->of_node instead (it is set to the same of_node as
base_dev by the callers of __genpd_dev_pm_attach) as it's more
consistent with existing code.

> +       if (of_parse_phandle(np, "required-opps", index)) {
> +               pstate = of_get_required_opp_performance_state(np, index);
> +               if (pstate < 0) {
> +                       ret = pstate;
> +                       dev_err(dev, "failed to set required performance state for power-domain %s: %d\n",
> +                               pd->name, ret);
> +               }
> +               dev_pm_genpd_set_performance_state(dev, pstate);
> +               dev_gpd_data(dev)->default_pstate = pstate;

This doesn't look entirely correct to me. If we fail to translate a
required opp to a performance state, we shouldn't try to set it.

Perhaps it's also easier to call
of_get_required_opp_performance_state() unconditionally of whether a
"required-opps" specifier exists. If it fails with the translation,
then we just skip setting a default state and continue with returning
1.

Would that work?

> +       }
>
> -       return ret ? -EPROBE_DEFER : 1;
> +       return ret ? ret : 1;
>  }
>
>  /**
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index 21a0577..67017c9 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -198,6 +198,7 @@ struct generic_pm_domain_data {
>         struct notifier_block *power_nb;
>         int cpu;
>         unsigned int performance_state;
> +       unsigned int default_pstate;
>         unsigned int rpm_pstate;
>         ktime_t next_wakeup;
>         void *data;
> --
> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
> of Code Aurora Forum, hosted by The Linux Foundation
>

Kind regards
Uffe
Rajendra Nayak Aug. 3, 2021, 4:38 a.m. | #3
On 8/2/2021 6:29 PM, Ulf Hansson wrote:
> On Tue, 20 Jul 2021 at 09:12, Rajendra Nayak <rnayak@codeaurora.org> wrote:
>>
>> Some devices within power domains with performance states do not
>> support DVFS, but still need to vote on a default/static state
>> while they are active. They can express this using the 'required-opps'
>> property in device tree, which points to the phandle of the OPP
>> supported by the corresponding power-domains.
>>
>> Add support to parse this information from DT and then set the
>> specified performance state during attach and drop it on detach.
>> runtime suspend/resume callbacks already have logic to drop/set
>> the vote as needed and should take care of dropping the default
>> perf state vote on runtime suspend and restore it back on runtime
>> resume.
>>
>> Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
>> ---
>>   drivers/base/power/domain.c | 28 +++++++++++++++++++++++++---
>>   include/linux/pm_domain.h   |  1 +
>>   2 files changed, 26 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
>> index a934c67..f454031 100644
>> --- a/drivers/base/power/domain.c
>> +++ b/drivers/base/power/domain.c
>> @@ -2598,6 +2598,12 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off)
>>
>>          dev_dbg(dev, "removing from PM domain %s\n", pd->name);
>>
>> +       /* Drop the default performance state */
>> +       if (dev_gpd_data(dev)->default_pstate) {
>> +               dev_pm_genpd_set_performance_state(dev, 0);
>> +               dev_gpd_data(dev)->default_pstate = 0;
>> +       }
>> +
>>          for (i = 1; i < GENPD_RETRY_MAX_MS; i <<= 1) {
>>                  ret = genpd_remove_device(pd, dev);
>>                  if (ret != -EAGAIN)
>> @@ -2635,9 +2641,10 @@ static void genpd_dev_pm_sync(struct device *dev)
>>   static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
>>                                   unsigned int index, bool power_on)
>>   {
>> +       struct device_node *np;
>>          struct of_phandle_args pd_args;
>>          struct generic_pm_domain *pd;
>> -       int ret;
>> +       int ret, pstate;
>>
>>          ret = of_parse_phandle_with_args(dev->of_node, "power-domains",
>>                                  "#power-domain-cells", index, &pd_args);
>> @@ -2675,10 +2682,25 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
>>                  genpd_unlock(pd);
>>          }
>>
>> -       if (ret)
>> +       if (ret) {
>>                  genpd_remove_device(pd, dev);
>> +               return -EPROBE_DEFER;
>> +       }
>> +
>> +       /* Set the default performance state */
>> +       np = base_dev->of_node;
> 
> Please use dev->of_node instead (it is set to the same of_node as
> base_dev by the callers of __genpd_dev_pm_attach) as it's more
> consistent with existing code.
> 
>> +       if (of_parse_phandle(np, "required-opps", index)) {
>> +               pstate = of_get_required_opp_performance_state(np, index);
>> +               if (pstate < 0) {
>> +                       ret = pstate;
>> +                       dev_err(dev, "failed to set required performance state for power-domain %s: %d\n",
>> +                               pd->name, ret);
>> +               }
>> +               dev_pm_genpd_set_performance_state(dev, pstate);
>> +               dev_gpd_data(dev)->default_pstate = pstate;
> 
> This doesn't look entirely correct to me. If we fail to translate a
> required opp to a performance state, we shouldn't try to set it.

yeah, that does not seem right at all :(

> Perhaps it's also easier to call
> of_get_required_opp_performance_state() unconditionally of whether a
> "required-opps" specifier exists. If it fails with the translation,
> then we just skip setting a default state and continue with returning
> 1.
> 
> Would that work?

I think it should, I'll redo the error handling, hopefully right this time,
and re-post. Thanks for the review.

> 
>> +       }
>>
>> -       return ret ? -EPROBE_DEFER : 1;
>> +       return ret ? ret : 1;
>>   }
>>
>>   /**
>> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
>> index 21a0577..67017c9 100644
>> --- a/include/linux/pm_domain.h
>> +++ b/include/linux/pm_domain.h
>> @@ -198,6 +198,7 @@ struct generic_pm_domain_data {
>>          struct notifier_block *power_nb;
>>          int cpu;
>>          unsigned int performance_state;
>> +       unsigned int default_pstate;
>>          unsigned int rpm_pstate;
>>          ktime_t next_wakeup;
>>          void *data;
>> --
>> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
>> of Code Aurora Forum, hosted by The Linux Foundation
>>
> 
> Kind regards
> Uffe
>
Ulf Hansson Aug. 4, 2021, 11:39 a.m. | #4
On Wed, 4 Aug 2021 at 13:08, Rajendra Nayak <rnayak@codeaurora.org> wrote:
>
>
> On 8/3/2021 10:08 AM, Rajendra Nayak wrote:
> >
> > On 8/2/2021 6:29 PM, Ulf Hansson wrote:
> >> On Tue, 20 Jul 2021 at 09:12, Rajendra Nayak <rnayak@codeaurora.org> wrote:
> >>>
> >>> Some devices within power domains with performance states do not
> >>> support DVFS, but still need to vote on a default/static state
> >>> while they are active. They can express this using the 'required-opps'
> >>> property in device tree, which points to the phandle of the OPP
> >>> supported by the corresponding power-domains.
> >>>
> >>> Add support to parse this information from DT and then set the
> >>> specified performance state during attach and drop it on detach.
> >>> runtime suspend/resume callbacks already have logic to drop/set
> >>> the vote as needed and should take care of dropping the default
> >>> perf state vote on runtime suspend and restore it back on runtime
> >>> resume.
> >>>
> >>> Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
> >>> ---
> >>>   drivers/base/power/domain.c | 28 +++++++++++++++++++++++++---
> >>>   include/linux/pm_domain.h   |  1 +
> >>>   2 files changed, 26 insertions(+), 3 deletions(-)
> >>>
> >>> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> >>> index a934c67..f454031 100644
> >>> --- a/drivers/base/power/domain.c
> >>> +++ b/drivers/base/power/domain.c
> >>> @@ -2598,6 +2598,12 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off)
> >>>
> >>>          dev_dbg(dev, "removing from PM domain %s\n", pd->name);
> >>>
> >>> +       /* Drop the default performance state */
> >>> +       if (dev_gpd_data(dev)->default_pstate) {
> >>> +               dev_pm_genpd_set_performance_state(dev, 0);
> >>> +               dev_gpd_data(dev)->default_pstate = 0;
> >>> +       }
> >>> +
> >>>          for (i = 1; i < GENPD_RETRY_MAX_MS; i <<= 1) {
> >>>                  ret = genpd_remove_device(pd, dev);
> >>>                  if (ret != -EAGAIN)
> >>> @@ -2635,9 +2641,10 @@ static void genpd_dev_pm_sync(struct device *dev)
> >>>   static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
> >>>                                   unsigned int index, bool power_on)
> >>>   {
> >>> +       struct device_node *np;
> >>>          struct of_phandle_args pd_args;
> >>>          struct generic_pm_domain *pd;
> >>> -       int ret;
> >>> +       int ret, pstate;
> >>>
> >>>          ret = of_parse_phandle_with_args(dev->of_node, "power-domains",
> >>>                                  "#power-domain-cells", index, &pd_args);
> >>> @@ -2675,10 +2682,25 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
> >>>                  genpd_unlock(pd);
> >>>          }
> >>>
> >>> -       if (ret)
> >>> +       if (ret) {
> >>>                  genpd_remove_device(pd, dev);
> >>> +               return -EPROBE_DEFER;
> >>> +       }
> >>> +
> >>> +       /* Set the default performance state */
> >>> +       np = base_dev->of_node;
> >>
> >> Please use dev->of_node instead (it is set to the same of_node as
> >> base_dev by the callers of __genpd_dev_pm_attach) as it's more
> >> consistent with existing code.
> >>
> >>> +       if (of_parse_phandle(np, "required-opps", index)) {
> >>> +               pstate = of_get_required_opp_performance_state(np, index);
> >>> +               if (pstate < 0) {
> >>> +                       ret = pstate;
> >>> +                       dev_err(dev, "failed to set required performance state for power-domain %s: %d\n",
> >>> +                               pd->name, ret);
> >>> +               }
> >>> +               dev_pm_genpd_set_performance_state(dev, pstate);
> >>> +               dev_gpd_data(dev)->default_pstate = pstate;
> >>
> >> This doesn't look entirely correct to me. If we fail to translate a
> >> required opp to a performance state, we shouldn't try to set it.
> >
> > yeah, that does not seem right at all :(
> >
> >> Perhaps it's also easier to call
> >> of_get_required_opp_performance_state() unconditionally of whether a
> >> "required-opps" specifier exists. If it fails with the translation,
> >> then we just skip setting a default state and continue with returning
> >> 1.
> >>
> >> Would that work?
>
> Looks like calling of_get_required_opp_performance_state() unconditionally
> makes it spit out a pr_err() in case the node is missing "required-opps" property,
> so I posted a v6 [1] with the check in place and adding the missing else
> condition.

I see.

Viresh, would it make sense to remove that print? I mean, the
required-opps property could be considered as optional and it seems a
bit silly that a pre-parsing of the property is needed to figure that
out.

>
> [1] https://lore.kernel.org/patchwork/project/lkml/list/?series=510727

Kind regards
Uffe
Viresh Kumar Aug. 5, 2021, 4:05 a.m. | #5
On 04-08-21, 13:39, Ulf Hansson wrote:
> Viresh, would it make sense to remove that print? I mean, the
> required-opps property could be considered as optional and it seems a
> bit silly that a pre-parsing of the property is needed to figure that
> out.

Sure, np.

Patch

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index a934c67..f454031 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -2598,6 +2598,12 @@  static void genpd_dev_pm_detach(struct device *dev, bool power_off)
 
 	dev_dbg(dev, "removing from PM domain %s\n", pd->name);
 
+	/* Drop the default performance state */
+	if (dev_gpd_data(dev)->default_pstate) {
+		dev_pm_genpd_set_performance_state(dev, 0);
+		dev_gpd_data(dev)->default_pstate = 0;
+	}
+
 	for (i = 1; i < GENPD_RETRY_MAX_MS; i <<= 1) {
 		ret = genpd_remove_device(pd, dev);
 		if (ret != -EAGAIN)
@@ -2635,9 +2641,10 @@  static void genpd_dev_pm_sync(struct device *dev)
 static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
 				 unsigned int index, bool power_on)
 {
+	struct device_node *np;
 	struct of_phandle_args pd_args;
 	struct generic_pm_domain *pd;
-	int ret;
+	int ret, pstate;
 
 	ret = of_parse_phandle_with_args(dev->of_node, "power-domains",
 				"#power-domain-cells", index, &pd_args);
@@ -2675,10 +2682,25 @@  static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
 		genpd_unlock(pd);
 	}
 
-	if (ret)
+	if (ret) {
 		genpd_remove_device(pd, dev);
+		return -EPROBE_DEFER;
+	}
+
+	/* Set the default performance state */
+	np = base_dev->of_node;
+	if (of_parse_phandle(np, "required-opps", index)) {
+		pstate = of_get_required_opp_performance_state(np, index);
+		if (pstate < 0) {
+			ret = pstate;
+			dev_err(dev, "failed to set required performance state for power-domain %s: %d\n",
+				pd->name, ret);
+		}
+		dev_pm_genpd_set_performance_state(dev, pstate);
+		dev_gpd_data(dev)->default_pstate = pstate;
+	}
 
-	return ret ? -EPROBE_DEFER : 1;
+	return ret ? ret : 1;
 }
 
 /**
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 21a0577..67017c9 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -198,6 +198,7 @@  struct generic_pm_domain_data {
 	struct notifier_block *power_nb;
 	int cpu;
 	unsigned int performance_state;
+	unsigned int default_pstate;
 	unsigned int rpm_pstate;
 	ktime_t	next_wakeup;
 	void *data;