Re: [PATCH v3 1/2] PM / Domains: Add support for 'required-opps' to set default perf state

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On 7/16/2021 10:43 AM, Rajendra Nayak wrote:
Some devics 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.
Also drop/set as part of runtime suspend/resume callbacks.

Signed-off-by: Rajendra Nayak <rnayak@xxxxxxxxxxxxxx>
---
  drivers/base/power/domain.c | 29 ++++++++++++++++++++++++++++-
  include/linux/pm_domain.h   |  1 +
  2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index a934c67..eef5507 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -917,6 +917,10 @@ static int genpd_runtime_suspend(struct device *dev)
  	if (irq_safe_dev_in_no_sleep_domain(dev, genpd))
  		return 0;
+ /* Drop the default performance state */
+	if (dev_gpd_data(dev)->default_pstate)
+		dev_pm_genpd_set_performance_state(dev, 0);
+
  	genpd_lock(genpd);
  	gpd_data->rpm_pstate = genpd_drop_performance_state(dev);
  	genpd_power_off(genpd, true, 0);
@@ -937,6 +941,7 @@ static int genpd_runtime_resume(struct device *dev)
  {
  	struct generic_pm_domain *genpd;
  	struct generic_pm_domain_data *gpd_data = dev_gpd_data(dev);
+	unsigned int default_pstate = gpd_data->default_pstate;
  	struct gpd_timing_data *td = &gpd_data->td;
  	bool runtime_pm = pm_runtime_enabled(dev);
  	ktime_t time_start;
@@ -968,6 +973,9 @@ static int genpd_runtime_resume(struct device *dev)
  	if (ret)
  		return ret;
+ /* Set the default performance state */
+	if (default_pstate)
+		dev_pm_genpd_set_performance_state(dev, default_pstate);
   out:
  	/* Measure resume latency. */
  	time_start = 0;
@@ -1000,6 +1008,8 @@ static int genpd_runtime_resume(struct device *dev)
  	genpd_stop_dev(genpd, dev);
  err_poweroff:
  	if (!pm_runtime_is_irq_safe(dev) || genpd_is_irq_safe(genpd)) {
+		if (default_pstate)
+			dev_pm_genpd_set_performance_state(dev, 0);
  		genpd_lock(genpd);
  		gpd_data->rpm_pstate = genpd_drop_performance_state(dev);
  		genpd_power_off(genpd, true, 0);
@@ -2598,6 +2608,12 @@ 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 +2651,10 @@ 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);
@@ -2678,6 +2695,16 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
  	if (ret)
  		genpd_remove_device(pd, dev);
+ /* 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) {
+			dev_pm_genpd_set_performance_state(dev, pstate);
+			dev_gpd_data(dev)->default_pstate = pstate;
+		}
+	}

I realized this needs better error handling after I sent it out,
I'll fix and respin.

+
  	return ret ? -EPROBE_DEFER : 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;


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