2 * drivers/base/power/domain_governor.c - Governors for device PM domains.
4 * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
6 * This file is released under the GPLv2.
9 #include <linux/init.h>
10 #include <linux/kernel.h>
11 #include <linux/pm_domain.h>
12 #include <linux/pm_qos.h>
13 #include <linux/hrtimer.h>
16 * default_stop_ok - Default PM domain governor routine for stopping devices.
17 * @dev: Device to check.
19 bool default_stop_ok(struct device
*dev
)
21 struct gpd_timing_data
*td
= &dev_gpd_data(dev
)->td
;
23 dev_dbg(dev
, "%s()\n", __func__
);
25 if (dev
->power
.max_time_suspended_ns
< 0 || td
->break_even_ns
== 0)
28 return td
->stop_latency_ns
+ td
->start_latency_ns
< td
->break_even_ns
29 && td
->break_even_ns
< dev
->power
.max_time_suspended_ns
;
33 * default_power_down_ok - Default generic PM domain power off governor routine.
34 * @pd: PM domain to check.
36 * This routine must be executed under the PM domain's lock.
38 static bool default_power_down_ok(struct dev_pm_domain
*pd
)
40 struct generic_pm_domain
*genpd
= pd_to_genpd(pd
);
41 struct gpd_link
*link
;
42 struct pm_domain_data
*pdd
;
43 s64 min_dev_off_time_ns
;
45 ktime_t time_now
= ktime_get();
47 off_on_time_ns
= genpd
->power_off_latency_ns
+
48 genpd
->power_on_latency_ns
;
50 * It doesn't make sense to remove power from the domain if saving
51 * the state of all devices in it and the power off/power on operations
54 * All devices in this domain have been stopped already at this point.
56 list_for_each_entry(pdd
, &genpd
->dev_list
, list_node
) {
59 to_gpd_data(pdd
)->td
.save_state_latency_ns
;
63 * Check if subdomains can be off for enough time.
65 * All subdomains have been powered off already at this point.
67 list_for_each_entry(link
, &genpd
->master_links
, master_node
) {
68 struct generic_pm_domain
*sd
= link
->slave
;
69 s64 sd_max_off_ns
= sd
->max_off_time_ns
;
71 if (sd_max_off_ns
< 0)
74 sd_max_off_ns
-= ktime_to_ns(ktime_sub(time_now
,
77 * Check if the subdomain is allowed to be off long enough for
78 * the current domain to turn off and on (that's how much time
79 * it will have to wait worst case).
81 if (sd_max_off_ns
<= off_on_time_ns
)
86 * Check if the devices in the domain can be off enough time.
88 min_dev_off_time_ns
= -1;
89 list_for_each_entry(pdd
, &genpd
->dev_list
, list_node
) {
90 struct gpd_timing_data
*td
;
91 struct device
*dev
= pdd
->dev
;
94 if (!dev
->driver
|| dev
->power
.max_time_suspended_ns
< 0)
97 td
= &to_gpd_data(pdd
)->td
;
98 dev_off_time_ns
= dev
->power
.max_time_suspended_ns
-
99 (td
->start_latency_ns
+ td
->restore_state_latency_ns
+
100 ktime_to_ns(ktime_sub(time_now
,
101 dev
->power
.suspend_time
)));
102 if (dev_off_time_ns
<= off_on_time_ns
)
105 if (min_dev_off_time_ns
> dev_off_time_ns
106 || min_dev_off_time_ns
< 0)
107 min_dev_off_time_ns
= dev_off_time_ns
;
110 if (min_dev_off_time_ns
< 0) {
112 * There are no latency constraints, so the domain can spend
113 * arbitrary time in the "off" state.
115 genpd
->max_off_time_ns
= -1;
120 * The difference between the computed minimum delta and the time needed
121 * to turn the domain on is the maximum theoretical time this domain can
122 * spend in the "off" state.
124 min_dev_off_time_ns
-= genpd
->power_on_latency_ns
;
127 * If the difference between the computed minimum delta and the time
128 * needed to turn the domain off and back on on is smaller than the
129 * domain's power break even time, removing power from the domain is not
132 if (genpd
->break_even_ns
>
133 min_dev_off_time_ns
- genpd
->power_off_latency_ns
)
136 genpd
->max_off_time_ns
= min_dev_off_time_ns
;
140 struct dev_power_governor simple_qos_governor
= {
141 .stop_ok
= default_stop_ok
,
142 .power_down_ok
= default_power_down_ok
,
145 static bool always_on_power_down_ok(struct dev_pm_domain
*domain
)
151 * pm_genpd_gov_always_on - A governor implementing an always-on policy
153 struct dev_power_governor pm_domain_always_on_gov
= {
154 .power_down_ok
= always_on_power_down_ok
,
155 .stop_ok
= default_stop_ok
,