Re: [RFC v2 2/6] PM / Domains: prepare for devices that might register a power state

[Lina Iyer <lina.iyer@linaro.org>]

Hi Marc,

Thanks for rebasing on top of my latest series.

On Tue, Oct 06 2015 at 08:27 -0600, Marc Titinger wrote:
>Devices may register an intermediate retention state into the domain upon
>
I may agree with the usability of dynamic adding a state to the domain,
but I dont see why a device attaching to a domain should bring about a
new domain state.

A domain should define its power states, independent of the devices that
may attach. The way I see it, devices have their own idle states and
domains have their own. I do see a relationship between possible domain
states depending on the states of the individual devices in the domain.
For ex, a CPU domain can only be in a retention state (low voltage,
memory retained), if its CPU devices are in retention state, i.e, the
domain cannot be powered off; alternately, the domain may be in
retention or power down if the CPU devices are in power down state.

Could you elaborate on why this is a need?

Thanks,
Lina

>attaching. Currently generic domain would register an array of states upon
>init. This patch prepares for later insertion (sort per depth, remove).
>
>Signed-off-by: Marc Titinger <mtitinger+renesas@baylibre.com>
>---
> drivers/base/power/domain.c | 189 +++++++++++++++++++-------------------------
> include/linux/pm_domain.h   |  18 ++++-
> 2 files changed, 97 insertions(+), 110 deletions(-)
>
>diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
>index 3e27a2b..e5f4c00b 100644
>--- a/drivers/base/power/domain.c
>+++ b/drivers/base/power/domain.c
>@@ -19,6 +19,7 @@
> #include <linux/sched.h>
> #include <linux/suspend.h>
> #include <linux/export.h>
>+#include <linux/sort.h>
>
> #define GENPD_RETRY_MAX_MS	250		/* Approximate */
>
>@@ -50,12 +51,6 @@
> 	__retval;								\
> })
>
>-#define GENPD_MAX_NAME_SIZE 20
>-
>-static int pm_genpd_alloc_states_names(struct generic_pm_domain *genpd,
>-				       const struct genpd_power_state *st,
>-				       unsigned int st_count);
>-
> static LIST_HEAD(gpd_list);
> static DEFINE_MUTEX(gpd_list_lock);
>
>@@ -1364,46 +1359,6 @@ static void genpd_free_dev_data(struct device *dev,
> 	dev_pm_put_subsys_data(dev);
> }
>
>-static int genpd_alloc_states_data(struct generic_pm_domain *genpd,
>-				   const struct genpd_power_state *st,
>-				   unsigned int st_count)
>-{
>-	int ret = 0;
>-	unsigned int i;
>-
>-	if (IS_ERR_OR_NULL(genpd)) {
>-		ret = -EINVAL;
>-		goto err;
>-	}
>-
>-	if (!st || (st_count < 1)) {
>-		ret = -EINVAL;
>-		goto err;
>-	}
>-
>-	/* Allocate the local memory to keep the states for this genpd */
>-	genpd->states = kcalloc(st_count, sizeof(*st), GFP_KERNEL);
>-	if (!genpd->states) {
>-		ret = -ENOMEM;
>-		goto err;
>-	}
>-
>-	for (i = 0; i < st_count; i++) {
>-		genpd->states[i].power_on_latency_ns =
>-			st[i].power_on_latency_ns;
>-		genpd->states[i].power_off_latency_ns =
>-			st[i].power_off_latency_ns;
>-	}
>-
>-	genpd->state_count = st_count;
>-
>-	/* to save memory, Name allocation will happen if debug is enabled */
>-	pm_genpd_alloc_states_names(genpd, st, st_count);
>-
>-err:
>-	return ret;
>-}
>-
> /**
>  * __pm_genpd_add_device - Add a device to an I/O PM domain.
>  * @genpd: PM domain to add the device to.
>@@ -1833,6 +1788,75 @@ static void genpd_lock_init(struct generic_pm_domain *genpd)
> 	}
> }
>
>+
>+/*
>+* state depth comparison function.
>+*/
>+static int state_cmp(const void *a, const void *b)
>+{
>+	struct genpd_power_state *state_a = (struct genpd_power_state *)(a);
>+	struct genpd_power_state *state_b = (struct genpd_power_state *)(b);
>+
>+	s64 depth_a =
>+		state_a->power_on_latency_ns + state_a->power_off_latency_ns;
>+	s64 depth_b =
>+		state_b->power_on_latency_ns + state_b->power_off_latency_ns;
>+
>+	return (depth_a > depth_b) ? 0 : -1;
>+}
>+
>+/*
>+* TODO: antagonist routine.
>+*/
>+int pm_genpd_insert_state(struct generic_pm_domain *genpd,
>+	const struct genpd_power_state *state)
>+{
>+	int ret = 0;
>+	int state_count = genpd->state_count;
>+
>+	if (IS_ERR_OR_NULL(genpd) || (!state))
>+		ret = -EINVAL;
>+
>+	if (state_count >= GENPD_POWER_STATES_MAX)
>+		ret = -ENOMEM;
>+
>+#ifdef CONFIG_PM_ADVANCED_DEBUG
>+	/* to save memory, Name allocation will happen if debug is enabled */
>+	genpd->states[state_count].name = kstrndup(state->name,
>+			GENPD_MAX_NAME_SIZE,
>+			GFP_KERNEL);
>+	if (!genpd->states[state_count].name) {
>+		pr_err("%s Failed to allocate state '%s' name.\n",
>+			genpd->name, state->name);
>+		ret = -ENOMEM;
>+	}
>+#endif
>+	genpd_lock(genpd);
>+
>+	if (!ret) {
>+		genpd->states[state_count].power_on_latency_ns =
>+			state->power_on_latency_ns;
>+		genpd->states[state_count].power_off_latency_ns =
>+			state->power_off_latency_ns;
>+		genpd->state_count++;
>+	}
>+
>+	/* sort from shallowest to deepest */
>+	sort(genpd->states, genpd->state_count,
>+		sizeof(genpd->states[0]), state_cmp, NULL /*generic swap */);
>+
>+	/* Sanity check for current state index */
>+	if (genpd->state_idx >= genpd->state_count) {
>+		pr_warn("pm domain %s Invalid initial state.\n", genpd->name);
>+		genpd->state_idx = genpd->state_count - 1;
>+	}
>+
>+	genpd_unlock(genpd);
>+
>+	return ret;
>+}
>+
>+
> /**
>  * pm_genpd_init - Initialize a generic I/O PM domain object.
>  * @genpd: PM domain object to initialize.
>@@ -1846,36 +1870,24 @@ void pm_genpd_init(struct generic_pm_domain *genpd,
> 		   const struct genpd_power_state *states,
> 		   unsigned int state_count, bool is_off)
> {
>-	static const struct genpd_power_state genpd_default_state[] = {
>-		{
>-			.name = "OFF",
>-			.power_off_latency_ns = 0,
>-			.power_on_latency_ns = 0,
>-		},
>-	};
>-	int ret;
>+	int i;
>
> 	if (IS_ERR_OR_NULL(genpd))
> 		return;
>
>-	/* If no states defined, use the default OFF state */
>-	if (!states || (state_count < 1))
>-		ret = genpd_alloc_states_data(genpd, genpd_default_state,
>-					      ARRAY_SIZE(genpd_default_state));
>-	else
>-		ret = genpd_alloc_states_data(genpd, states, state_count);
>-
>-	if (ret) {
>-		pr_err("Fail to allocate states for %s\n", genpd->name);
>-		return;
>-	}
>+	/* simply use an array, we wish to add/remove new retention states
>+	   from later device init/exit. */
>+	memset(genpd->states, 0, GENPD_POWER_STATES_MAX
>+	       * sizeof(struct genpd_power_state));
>
>-	/* Sanity check for initial state */
>-	if (genpd->state_idx >= genpd->state_count) {
>-		pr_warn("pm domain %s Invalid initial state.\n",
>-			genpd->name);
>-		genpd->state_idx = genpd->state_count - 1;
>-	}
>+	if (!states || !state_count) {
>+		/* require a provider for a default state */
>+		genpd->state_count = 0;
>+		genpd->state_idx = 0;
>+	} else
>+		for (i = 0; i < state_count; i++)
>+			if (pm_genpd_insert_state(genpd, &states[i]))
>+				return;
>
> 	INIT_LIST_HEAD(&genpd->master_links);
> 	INIT_LIST_HEAD(&genpd->slave_links);
>@@ -2233,33 +2245,6 @@ EXPORT_SYMBOL_GPL(genpd_dev_pm_attach);
> #include <linux/kobject.h>
> static struct dentry *pm_genpd_debugfs_dir;
>
>-static int pm_genpd_alloc_states_names(struct generic_pm_domain *genpd,
>-				       const struct genpd_power_state *st,
>-				       unsigned int st_count)
>-{
>-	unsigned int i;
>-
>-	if (IS_ERR_OR_NULL(genpd))
>-		return -EINVAL;
>-
>-	if (genpd->state_count != st_count) {
>-		pr_err("Invalid allocated state count\n");
>-		return -EINVAL;
>-	}
>-
>-	for (i = 0; i < st_count; i++) {
>-		genpd->states[i].name = kstrndup(st[i].name,
>-				GENPD_MAX_NAME_SIZE, GFP_KERNEL);
>-		if (!genpd->states[i].name) {
>-			pr_err("%s Failed to allocate state %d name.\n",
>-				genpd->name, i);
>-			return -ENOMEM;
>-		}
>-	}
>-
>-	return 0;
>-}
>-
> /*
>  * TODO: This function is a slightly modified version of rtpm_status_show
>  * from sysfs.c, so generalize it.
>@@ -2398,12 +2383,4 @@ static void __exit pm_genpd_debug_exit(void)
> {
> 	debugfs_remove_recursive(pm_genpd_debugfs_dir);
> }
>-__exitcall(pm_genpd_debug_exit);
>-#else
>-static inline int pm_genpd_alloc_states_names(struct generic_pm_domain *genpd,
>-					const struct genpd_power_state *st,
>-					unsigned int st_count)
>-{
>-	return 0;
>-}
> #endif /* CONFIG_PM_ADVANCED_DEBUG */
>diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
>index 9d37292..8a4eab0 100644
>--- a/include/linux/pm_domain.h
>+++ b/include/linux/pm_domain.h
>@@ -45,6 +45,13 @@ struct gpd_cpuidle_data {
> 	struct cpuidle_state *idle_state;
> };
>
>+
>+/* Arbitrary max number of devices registering a special
>+ * retention state with the PD, to keep things simple.
>+ */
>+#define GENPD_POWER_STATES_MAX	12
>+#define GENPD_MAX_NAME_SIZE	40
>+
> struct genpd_power_state {
> 	char *name;
> 	s64 power_off_latency_ns;
>@@ -80,7 +87,8 @@ struct generic_pm_domain {
> 			   struct device *dev);
> 	unsigned int flags;		/* Bit field of configs for genpd */
>
>-	struct genpd_power_state *states;
>+	struct genpd_power_state states[GENPD_POWER_STATES_MAX];
>+
> 	unsigned int state_count; /* number of states */
> 	unsigned int state_idx; /* state that genpd will go to when off */
>
>@@ -159,10 +167,12 @@ extern int pm_genpd_attach_cpuidle(struct generic_pm_domain *genpd, int state);
> extern int pm_genpd_name_attach_cpuidle(const char *name, int state);
> extern int pm_genpd_detach_cpuidle(struct generic_pm_domain *genpd);
> extern int pm_genpd_name_detach_cpuidle(const char *name);
>+extern int pm_genpd_insert_state(struct generic_pm_domain *genpd,
>+			const struct genpd_power_state *state);
> extern void pm_genpd_init(struct generic_pm_domain *genpd,
>-			  struct dev_power_governor *gov,
>-			  const struct genpd_power_state *states,
>-			  unsigned int state_count, bool is_off);
>+			struct dev_power_governor *gov,
>+			const struct genpd_power_state *states,
>+			unsigned int state_count, bool is_off);
>
> extern int pm_genpd_poweron(struct generic_pm_domain *genpd);
> extern int pm_genpd_name_poweron(const char *domain_name);
>-- 
>1.9.1
>