From fc5cbf0c94b6f7fd62fdddff892207290510945d Mon Sep 17 00:00:00 2001 From: Axel Haslam Date: Mon, 15 Feb 2016 11:10:51 +0100 Subject: [PATCH] PM / Domains: Support for multiple states Some hardware (eg. OMAP), has the ability to enter different low power modes for a given power domain. This allows for more fine grained control over the power state of the platform. As a typical example, some registers of the hardware may be implemented with retention flip-flops and be able to retain their state at lower voltages allowing for faster on/off latencies and an increased window of opportunity to enter an intermediate low power state other than "off" When trying to set a power domain to off, the genpd governor will choose the deepest state that will respect the qos constraints of all the devices and sub-domains on the power domain. The state chosen by the governor is saved in the "state_idx" field of the generic_pm_domain structure and shall be used by the power_off and power_on callbacks to perform the necessary actions to set the power domain into (and out of) the state indicated by state_idx. States must be declared in ascending order from shallowest to deepest, deepest meaning the state which takes longer to enter and exit. For platforms that don't declare any states, a single a single "off" state is used. Once all platforms are converted to use the state array, the legacy on/off latencies will be removed. [ Lina: Modified genpd state initialization and remove use of save_state_latency_ns in genpd timing data ] Suggested-by: Kevin Hilman Signed-off-by: Lina Iyer Signed-off-by: Axel Haslam Acked-by: Ulf Hansson Signed-off-by: Rafael J. Wysocki --- drivers/base/power/domain.c | 39 +++++++++++++++++++--- drivers/base/power/domain_governor.c | 64 ++++++++++++++++++++++-------------- include/linux/pm_domain.h | 11 +++++++ 3 files changed, 85 insertions(+), 29 deletions(-) diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c index 301b785f9f56..4c6f46b5c444 100644 --- a/drivers/base/power/domain.c +++ b/drivers/base/power/domain.c @@ -104,6 +104,7 @@ static void genpd_sd_counter_inc(struct generic_pm_domain *genpd) static int genpd_power_on(struct generic_pm_domain *genpd, bool timed) { + unsigned int state_idx = genpd->state_idx; ktime_t time_start; s64 elapsed_ns; int ret; @@ -120,10 +121,10 @@ static int genpd_power_on(struct generic_pm_domain *genpd, bool timed) return ret; elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start)); - if (elapsed_ns <= genpd->power_on_latency_ns) + if (elapsed_ns <= genpd->states[state_idx].power_on_latency_ns) return ret; - genpd->power_on_latency_ns = elapsed_ns; + genpd->states[state_idx].power_on_latency_ns = elapsed_ns; genpd->max_off_time_changed = true; pr_debug("%s: Power-%s latency exceeded, new value %lld ns\n", genpd->name, "on", elapsed_ns); @@ -133,6 +134,7 @@ static int genpd_power_on(struct generic_pm_domain *genpd, bool timed) static int genpd_power_off(struct generic_pm_domain *genpd, bool timed) { + unsigned int state_idx = genpd->state_idx; ktime_t time_start; s64 elapsed_ns; int ret; @@ -149,10 +151,10 @@ static int genpd_power_off(struct generic_pm_domain *genpd, bool timed) return ret; elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start)); - if (elapsed_ns <= genpd->power_off_latency_ns) + if (elapsed_ns <= genpd->states[state_idx].power_off_latency_ns) return ret; - genpd->power_off_latency_ns = elapsed_ns; + genpd->states[state_idx].power_off_latency_ns = elapsed_ns; genpd->max_off_time_changed = true; pr_debug("%s: Power-%s latency exceeded, new value %lld ns\n", genpd->name, "off", elapsed_ns); @@ -585,6 +587,8 @@ static void pm_genpd_sync_poweroff(struct generic_pm_domain *genpd, || atomic_read(&genpd->sd_count) > 0) return; + /* Choose the deepest state when suspending */ + genpd->state_idx = genpd->state_count - 1; genpd_power_off(genpd, timed); genpd->status = GPD_STATE_POWER_OFF; @@ -1508,6 +1512,26 @@ void pm_genpd_init(struct generic_pm_domain *genpd, genpd->dev_ops.start = pm_clk_resume; } + if (genpd->state_idx >= GENPD_MAX_NUM_STATES) { + pr_warn("Initial state index out of bounds.\n"); + genpd->state_idx = GENPD_MAX_NUM_STATES - 1; + } + + if (genpd->state_count > GENPD_MAX_NUM_STATES) { + pr_warn("Limiting states to %d\n", GENPD_MAX_NUM_STATES); + genpd->state_count = GENPD_MAX_NUM_STATES; + } + + /* Use only one "off" state if there were no states declared */ + if (genpd->state_count == 0) { + genpd->states[0].power_on_latency_ns = + genpd->power_on_latency_ns; + genpd->states[0].power_off_latency_ns = + genpd->power_off_latency_ns; + + genpd->state_count = 1; + } + mutex_lock(&gpd_list_lock); list_add(&genpd->gpd_list_node, &gpd_list); mutex_unlock(&gpd_list_lock); @@ -1872,7 +1896,12 @@ static int pm_genpd_summary_one(struct seq_file *s, if (WARN_ON(genpd->status >= ARRAY_SIZE(status_lookup))) goto exit; - seq_printf(s, "%-30s %-15s ", genpd->name, status_lookup[genpd->status]); + seq_printf(s, "%-30s %s", genpd->name, status_lookup[genpd->status]); + + if (genpd->status == GPD_STATE_POWER_OFF) + seq_printf(s, " %-13d ", genpd->state_idx); + else + seq_printf(s, " %-15s ", ""); /* * Modifications on the list require holding locks on both diff --git a/drivers/base/power/domain_governor.c b/drivers/base/power/domain_governor.c index 1e937ac5f456..00a5436dd44b 100644 --- a/drivers/base/power/domain_governor.c +++ b/drivers/base/power/domain_governor.c @@ -98,7 +98,8 @@ static bool default_stop_ok(struct device *dev) * * This routine must be executed under the PM domain's lock. */ -static bool default_power_down_ok(struct dev_pm_domain *pd) +static bool __default_power_down_ok(struct dev_pm_domain *pd, + unsigned int state) { struct generic_pm_domain *genpd = pd_to_genpd(pd); struct gpd_link *link; @@ -106,27 +107,9 @@ static bool default_power_down_ok(struct dev_pm_domain *pd) s64 min_off_time_ns; s64 off_on_time_ns; - if (genpd->max_off_time_changed) { - struct gpd_link *link; - - /* - * We have to invalidate the cached results for the masters, so - * use the observation that default_power_down_ok() is not - * going to be called for any master until this instance - * returns. - */ - list_for_each_entry(link, &genpd->slave_links, slave_node) - link->master->max_off_time_changed = true; - - genpd->max_off_time_changed = false; - genpd->cached_power_down_ok = false; - genpd->max_off_time_ns = -1; - } else { - return genpd->cached_power_down_ok; - } + off_on_time_ns = genpd->states[state].power_off_latency_ns + + genpd->states[state].power_on_latency_ns; - off_on_time_ns = genpd->power_off_latency_ns + - genpd->power_on_latency_ns; min_off_time_ns = -1; /* @@ -186,8 +169,6 @@ static bool default_power_down_ok(struct dev_pm_domain *pd) min_off_time_ns = constraint_ns; } - genpd->cached_power_down_ok = true; - /* * If the computed minimum device off time is negative, there are no * latency constraints, so the domain can spend arbitrary time in the @@ -201,10 +182,45 @@ static bool default_power_down_ok(struct dev_pm_domain *pd) * time and the time needed to turn the domain on is the maximum * theoretical time this domain can spend in the "off" state. */ - genpd->max_off_time_ns = min_off_time_ns - genpd->power_on_latency_ns; + genpd->max_off_time_ns = min_off_time_ns - + genpd->states[state].power_on_latency_ns; return true; } +static bool default_power_down_ok(struct dev_pm_domain *pd) +{ + struct generic_pm_domain *genpd = pd_to_genpd(pd); + struct gpd_link *link; + + if (!genpd->max_off_time_changed) + return genpd->cached_power_down_ok; + + /* + * We have to invalidate the cached results for the masters, so + * use the observation that default_power_down_ok() is not + * going to be called for any master until this instance + * returns. + */ + list_for_each_entry(link, &genpd->slave_links, slave_node) + link->master->max_off_time_changed = true; + + genpd->max_off_time_ns = -1; + genpd->max_off_time_changed = false; + genpd->cached_power_down_ok = true; + genpd->state_idx = genpd->state_count - 1; + + /* Find a state to power down to, starting from the deepest. */ + while (!__default_power_down_ok(pd, genpd->state_idx)) { + if (genpd->state_idx == 0) { + genpd->cached_power_down_ok = false; + break; + } + genpd->state_idx--; + } + + return genpd->cached_power_down_ok; +} + static bool always_on_power_down_ok(struct dev_pm_domain *domain) { return false; diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h index db21d3995f7e..1726c4ac6529 100644 --- a/include/linux/pm_domain.h +++ b/include/linux/pm_domain.h @@ -19,6 +19,8 @@ /* Defines used for the flags field in the struct generic_pm_domain */ #define GENPD_FLAG_PM_CLK (1U << 0) /* PM domain uses PM clk */ +#define GENPD_MAX_NUM_STATES 8 /* Number of possible low power states */ + enum gpd_status { GPD_STATE_ACTIVE = 0, /* PM domain is active */ GPD_STATE_POWER_OFF, /* PM domain is off */ @@ -37,6 +39,11 @@ struct gpd_dev_ops { bool (*active_wakeup)(struct device *dev); }; +struct genpd_power_state { + s64 power_off_latency_ns; + s64 power_on_latency_ns; +}; + struct generic_pm_domain { struct dev_pm_domain domain; /* PM domain operations */ struct list_head gpd_list_node; /* Node in the global PM domains list */ @@ -66,6 +73,10 @@ struct generic_pm_domain { void (*detach_dev)(struct generic_pm_domain *domain, struct device *dev); unsigned int flags; /* Bit field of configs for genpd */ + struct genpd_power_state states[GENPD_MAX_NUM_STATES]; + unsigned int state_count; /* number of states */ + unsigned int state_idx; /* state that genpd will go to when off */ + }; static inline struct generic_pm_domain *pd_to_genpd(struct dev_pm_domain *pd) -- 2.11.0