drivers/gpu/drm/i915/intel_wakeref.c

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright © 2019 Intel Corporation
   5  */
   6
   7 #include "intel_runtime_pm.h"
   8 #include "i915_gem.h"
   9
  10 static void rpm_get(struct intel_runtime_pm *rpm, struct intel_wakeref *wf)
  11 {
  12         wf->wakeref = intel_runtime_pm_get(rpm);
  13 }
  14
  15 static void rpm_put(struct intel_runtime_pm *rpm, struct intel_wakeref *wf)
  16 {
  17         intel_wakeref_t wakeref = fetch_and_zero(&wf->wakeref);
  18
  19         intel_runtime_pm_put(rpm, wakeref);
  20         GEM_BUG_ON(!wakeref);
  21 }
  22
  23 int __intel_wakeref_get_first(struct intel_runtime_pm *rpm,
  24                               struct intel_wakeref *wf,
  25                               int (*fn)(struct intel_wakeref *wf))
  26 {
  27         /*
  28          * Treat get/put as different subclasses, as we may need to run
  29          * the put callback from under the shrinker and do not want to
  30          * cross-contanimate that callback with any extra work performed
  31          * upon acquiring the wakeref.
  32          */
  33         mutex_lock_nested(&wf->mutex, SINGLE_DEPTH_NESTING);
  34         if (!atomic_read(&wf->count)) {
  35                 int err;
  36
  37                 rpm_get(rpm, wf);
  38
  39                 err = fn(wf);
  40                 if (unlikely(err)) {
  41                         rpm_put(rpm, wf);
  42                         mutex_unlock(&wf->mutex);
  43                         return err;
  44                 }
  45
  46                 smp_mb__before_atomic(); /* release wf->count */
  47         }
  48         atomic_inc(&wf->count);
  49         mutex_unlock(&wf->mutex);
  50
  51         return 0;
  52 }
  53
  54 int __intel_wakeref_put_last(struct intel_runtime_pm *rpm,
  55                              struct intel_wakeref *wf,
  56                              int (*fn)(struct intel_wakeref *wf))
  57 {
  58         int err;
  59
  60         err = fn(wf);
  61         if (likely(!err))
  62                 rpm_put(rpm, wf);
  63         else
  64                 atomic_inc(&wf->count);
  65         mutex_unlock(&wf->mutex);
  66
  67         return err;
  68 }
  69
  70 void __intel_wakeref_init(struct intel_wakeref *wf, struct lock_class_key *key)
  71 {
  72         __mutex_init(&wf->mutex, "wakeref", key);
  73         atomic_set(&wf->count, 0);
  74         wf->wakeref = 0;
  75 }
  76
  77 static void wakeref_auto_timeout(struct timer_list *t)
  78 {
  79         struct intel_wakeref_auto *wf = from_timer(wf, t, timer);
  80         intel_wakeref_t wakeref;
  81         unsigned long flags;
  82
  83         if (!refcount_dec_and_lock_irqsave(&wf->count, &wf->lock, &flags))
  84                 return;
  85
  86         wakeref = fetch_and_zero(&wf->wakeref);
  87         spin_unlock_irqrestore(&wf->lock, flags);
  88
  89         intel_runtime_pm_put(wf->rpm, wakeref);
  90 }
  91
  92 void intel_wakeref_auto_init(struct intel_wakeref_auto *wf,
  93                              struct intel_runtime_pm *rpm)
  94 {
  95         spin_lock_init(&wf->lock);
  96         timer_setup(&wf->timer, wakeref_auto_timeout, 0);
  97         refcount_set(&wf->count, 0);
  98         wf->wakeref = 0;
  99         wf->rpm = rpm;
 100 }
 101
 102 void intel_wakeref_auto(struct intel_wakeref_auto *wf, unsigned long timeout)
 103 {
 104         unsigned long flags;
 105
 106         if (!timeout) {
 107                 if (del_timer_sync(&wf->timer))
 108                         wakeref_auto_timeout(&wf->timer);
 109                 return;
 110         }
 111
 112         /* Our mission is that we only extend an already active wakeref */
 113         assert_rpm_wakelock_held(wf->rpm);
 114
 115         if (!refcount_inc_not_zero(&wf->count)) {
 116                 spin_lock_irqsave(&wf->lock, flags);
 117                 if (!refcount_inc_not_zero(&wf->count)) {
 118                         GEM_BUG_ON(wf->wakeref);
 119                         wf->wakeref = intel_runtime_pm_get_if_in_use(wf->rpm);
 120                         refcount_set(&wf->count, 1);
 121                 }
 122                 spin_unlock_irqrestore(&wf->lock, flags);
 123         }
 124
 125         /*
 126          * If we extend a pending timer, we will only get a single timer
 127          * callback and so need to cancel the local inc by running the
 128          * elided callback to keep the wf->count balanced.
 129          */
 130         if (mod_timer(&wf->timer, jiffies + timeout))
 131                 wakeref_auto_timeout(&wf->timer);
 132 }
 133
 134 void intel_wakeref_auto_fini(struct intel_wakeref_auto *wf)
 135 {
 136         intel_wakeref_auto(wf, 0);
 137         GEM_BUG_ON(wf->wakeref);
 138 }