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b02c999a RW |
1 | /* |
2 | * drivers/base/power/domain_governor.c - Governors for device PM domains. | |
3 | * | |
4 | * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp. | |
5 | * | |
6 | * This file is released under the GPLv2. | |
7 | */ | |
8 | ||
9 | #include <linux/init.h> | |
10 | #include <linux/kernel.h> | |
11 | #include <linux/pm_domain.h> | |
12 | #include <linux/pm_qos.h> | |
221e9b58 | 13 | #include <linux/hrtimer.h> |
b02c999a RW |
14 | |
15 | /** | |
16 | * default_stop_ok - Default PM domain governor routine for stopping devices. | |
17 | * @dev: Device to check. | |
18 | */ | |
19 | bool default_stop_ok(struct device *dev) | |
20 | { | |
21 | struct gpd_timing_data *td = &dev_gpd_data(dev)->td; | |
22 | ||
23 | dev_dbg(dev, "%s()\n", __func__); | |
24 | ||
25 | if (dev->power.max_time_suspended_ns < 0 || td->break_even_ns == 0) | |
26 | return true; | |
27 | ||
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; | |
30 | } | |
31 | ||
221e9b58 RW |
32 | /** |
33 | * default_power_down_ok - Default generic PM domain power off governor routine. | |
34 | * @pd: PM domain to check. | |
35 | * | |
36 | * This routine must be executed under the PM domain's lock. | |
37 | */ | |
38 | static bool default_power_down_ok(struct dev_pm_domain *pd) | |
39 | { | |
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; | |
44 | s64 off_on_time_ns; | |
45 | ktime_t time_now = ktime_get(); | |
46 | ||
47 | off_on_time_ns = genpd->power_off_latency_ns + | |
48 | genpd->power_on_latency_ns; | |
49 | /* | |
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 | |
52 | * take too much time. | |
53 | * | |
54 | * All devices in this domain have been stopped already at this point. | |
55 | */ | |
56 | list_for_each_entry(pdd, &genpd->dev_list, list_node) { | |
57 | if (pdd->dev->driver) | |
58 | off_on_time_ns += | |
59 | to_gpd_data(pdd)->td.save_state_latency_ns; | |
60 | } | |
61 | ||
62 | /* | |
63 | * Check if subdomains can be off for enough time. | |
64 | * | |
65 | * All subdomains have been powered off already at this point. | |
66 | */ | |
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; | |
70 | ||
71 | if (sd_max_off_ns < 0) | |
72 | continue; | |
73 | ||
74 | sd_max_off_ns -= ktime_to_ns(ktime_sub(time_now, | |
75 | sd->power_off_time)); | |
76 | /* | |
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). | |
80 | */ | |
81 | if (sd_max_off_ns <= off_on_time_ns) | |
82 | return false; | |
83 | } | |
84 | ||
85 | /* | |
86 | * Check if the devices in the domain can be off enough time. | |
87 | */ | |
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; | |
92 | s64 dev_off_time_ns; | |
93 | ||
94 | if (!dev->driver || dev->power.max_time_suspended_ns < 0) | |
95 | continue; | |
96 | ||
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) | |
103 | return false; | |
104 | ||
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; | |
108 | } | |
109 | ||
110 | if (min_dev_off_time_ns < 0) { | |
111 | /* | |
112 | * There are no latency constraints, so the domain can spend | |
113 | * arbitrary time in the "off" state. | |
114 | */ | |
115 | genpd->max_off_time_ns = -1; | |
116 | return true; | |
117 | } | |
118 | ||
119 | /* | |
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. | |
123 | */ | |
124 | min_dev_off_time_ns -= genpd->power_on_latency_ns; | |
125 | ||
126 | /* | |
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 | |
130 | * worth it. | |
131 | */ | |
132 | if (genpd->break_even_ns > | |
133 | min_dev_off_time_ns - genpd->power_off_latency_ns) | |
134 | return false; | |
135 | ||
136 | genpd->max_off_time_ns = min_dev_off_time_ns; | |
137 | return true; | |
138 | } | |
139 | ||
b02c999a RW |
140 | struct dev_power_governor simple_qos_governor = { |
141 | .stop_ok = default_stop_ok, | |
221e9b58 | 142 | .power_down_ok = default_power_down_ok, |
b02c999a | 143 | }; |