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| 2 | |
| 3 | * fair_share.c - A simple weight based Thermal governor
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| 4 | *
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| 5 | * Copyright (C) 2012 Intel Corp
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| 6 | * Copyright (C) 2012 Durgadoss R <[email protected]>
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| 7 | *
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| 8 | * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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| 9 | *
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| 10 | * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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| 11 |
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| 12 |
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| 13 | #include <linux/thermal.h>
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| 14 | #include "thermal_trace.h"
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| 15 |
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| 16 | #include "thermal_core.h"
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| 17 |
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| 18 | static int get_trip_level(struct thermal_zone_device *tz)
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| 19 | {
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| 20 | const struct thermal_trip_desc *level_td = NULL;
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| 21 | const struct thermal_trip_desc *td;
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| 22 | int trip_level = -1;
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| 23 |
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| 24 | for_each_trip_desc(tz, td) {
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| 25 | if (td->threshold > tz->temperature)
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| 26 | continue;
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| 27 |
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| 28 | trip_level++;
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| 29 |
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| 30 | if (!level_td || td->threshold > level_td->threshold)
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| 31 | level_td = td;
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| 32 | }
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| 33 |
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| 34 |
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| 35 | if (trip_level < 0)
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| 36 | return 0;
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| 37 |
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| 38 | trace_thermal_zone_trip(tz, thermal_zone_trip_id(tz, &level_td->trip),
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| 39 | level_td->trip.type);
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| 40 |
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| 41 | return trip_level;
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| 42 | }
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| 43 |
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| 44 | |
| 45 | * fair_share_throttle - throttles devices associated with the given zone
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| 46 | * @tz: thermal_zone_device
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| 47 | * @td: trip point descriptor
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| 48 | * @trip_level: number of trips crossed by the zone temperature
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| 49 | *
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| 50 | * Throttling Logic: This uses three parameters to calculate the new
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| 51 | * throttle state of the cooling devices associated with the given zone.
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| 52 | *
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| 53 | * Parameters used for Throttling:
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| 54 | * P1. max_state: Maximum throttle state exposed by the cooling device.
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| 55 | * P2. weight[i]/total_weight:
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| 56 | * How 'effective' the 'i'th device is, in cooling the given zone.
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| 57 | * P3. trip_level/max_no_of_trips:
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| 58 | * This describes the extent to which the devices should be throttled.
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| 59 | * We do not want to throttle too much when we trip a lower temperature,
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| 60 | * whereas the throttling is at full swing if we trip critical levels.
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| 61 | * new_state of cooling device = P3 * P2 * P1
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| 62 |
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| 63 | static void fair_share_throttle(struct thermal_zone_device *tz,
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| 64 | const struct thermal_trip_desc *td,
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| 65 | int trip_level)
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| 66 | {
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| 67 | struct thermal_instance *instance;
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| 68 | int total_weight = 0;
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| 69 | int nr_instances = 0;
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| 70 |
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| 71 | list_for_each_entry(instance, &td->thermal_instances, trip_node) {
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| 72 | total_weight += instance->weight;
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| 73 | nr_instances++;
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| 74 | }
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| 75 |
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| 76 | list_for_each_entry(instance, &td->thermal_instances, trip_node) {
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| 77 | struct thermal_cooling_device *cdev = instance->cdev;
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| 78 | u64 dividend;
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| 79 | u32 divisor;
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| 80 |
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| 81 | dividend = trip_level;
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| 82 | dividend *= cdev->max_state;
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| 83 | divisor = tz->num_trips;
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| 84 | if (total_weight) {
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| 85 | dividend *= instance->weight;
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| 86 | divisor *= total_weight;
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| 87 | } else {
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| 88 | divisor *= nr_instances;
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| 89 | }
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| 90 | instance->target = div_u64(dividend, divisor);
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| 91 |
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| 92 | thermal_cdev_update_nocheck(cdev);
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| 93 | }
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| 94 | }
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| 95 |
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| 96 | static void fair_share_manage(struct thermal_zone_device *tz)
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| 97 | {
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| 98 | int trip_level = get_trip_level(tz);
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| 99 | const struct thermal_trip_desc *td;
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| 100 |
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| 101 | lockdep_assert_held(&tz->lock);
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| 102 |
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| 103 | for_each_trip_desc(tz, td) {
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| 104 | const struct thermal_trip *trip = &td->trip;
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| 105 |
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| 106 | if (trip->temperature == THERMAL_TEMP_INVALID ||
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| 107 | trip->type == THERMAL_TRIP_CRITICAL ||
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| 108 | trip->type == THERMAL_TRIP_HOT)
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| 109 | continue;
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| 110 |
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| 111 | fair_share_throttle(tz, td, trip_level);
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| 112 | }
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| 113 | }
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| 114 |
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| 115 | static struct thermal_governor thermal_gov_fair_share = {
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| 116 | .name = "fair_share",
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| 117 | .manage = fair_share_manage,
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| 118 | };
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| 119 | THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share);
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