drivers/gpu/drm/i915/intel_wakeref.c

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright © 2019 Intel Corporation
   5  */
   6
   7 #include "intel_drv.h"
   8 #include "intel_wakeref.h"
   9
  10 static void rpm_get(struct drm_i915_private *i915, struct intel_wakeref *wf)
  11 {
  12         wf->wakeref = intel_runtime_pm_get(i915);
  13 }
  14
  15 static void rpm_put(struct drm_i915_private *i915, struct intel_wakeref *wf)
  16 {
  17         intel_wakeref_t wakeref = fetch_and_zero(&wf->wakeref);
  18
  19         intel_runtime_pm_put(i915, wakeref);
  20         GEM_BUG_ON(!wakeref);
  21 }
  22
  23 int __intel_wakeref_get_first(struct drm_i915_private *i915,
  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(i915, wf);
  38
  39                 err = fn(wf);
  40                 if (unlikely(err)) {
  41                         rpm_put(i915, 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 drm_i915_private *i915,
  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(i915, 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 }