include/drm/drm_modeset_lock.h

   1 /*
   2  * Copyright (C) 2014 Red Hat
   3  * Author: Rob Clark <robdclark@gmail.com>
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a
   6  * copy of this software and associated documentation files (the "Software"),
   7  * to deal in the Software without restriction, including without limitation
   8  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   9  * and/or sell copies of the Software, and to permit persons to whom the
  10  * Software is furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice shall be included in
  13  * all copies or substantial portions of the Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  19  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  20  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  21  * OTHER DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 #ifndef DRM_MODESET_LOCK_H_
  25 #define DRM_MODESET_LOCK_H_
  26
  27 #include <linux/ww_mutex.h>
  28
  29 struct drm_modeset_lock;
  30
  31 /**
  32  * struct drm_modeset_acquire_ctx - locking context (see ww_acquire_ctx)
  33  * @ww_ctx: base acquire ctx
  34  * @contended: used internally for -EDEADLK handling
  35  * @locked: list of held locks
  36  * @trylock_only: trylock mode used in atomic contexts/panic notifiers
  37  *
  38  * Each thread competing for a set of locks must use one acquire
  39  * ctx.  And if any lock fxn returns -EDEADLK, it must backoff and
  40  * retry.
  41  */
  42 struct drm_modeset_acquire_ctx {
  43
  44         struct ww_acquire_ctx ww_ctx;
  45
  46         /*
  47          * Contended lock: if a lock is contended you should only call
  48          * drm_modeset_backoff() which drops locks and slow-locks the
  49          * contended lock.
  50          */
  51         struct drm_modeset_lock *contended;
  52
  53         /*
  54          * list of held locks (drm_modeset_lock)
  55          */
  56         struct list_head locked;
  57
  58         /*
  59          * Trylock mode, use only for panic handlers!
  60          */
  61         bool trylock_only;
  62 };
  63
  64 /**
  65  * struct drm_modeset_lock - used for locking modeset resources.
  66  * @mutex: resource locking
  67  * @head: used to hold it's place on state->locked list when
  68  *    part of an atomic update
  69  *
  70  * Used for locking CRTCs and other modeset resources.
  71  */
  72 struct drm_modeset_lock {
  73         /*
  74          * modeset lock
  75          */
  76         struct ww_mutex mutex;
  77
  78         /*
  79          * Resources that are locked as part of an atomic update are added
  80          * to a list (so we know what to unlock at the end).
  81          */
  82         struct list_head head;
  83 };
  84
  85 extern struct ww_class crtc_ww_class;
  86
  87 void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
  88                 uint32_t flags);
  89 void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx);
  90 void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx);
  91 void drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx);
  92 int drm_modeset_backoff_interruptible(struct drm_modeset_acquire_ctx *ctx);
  93
  94 /**
  95  * drm_modeset_lock_init - initialize lock
  96  * @lock: lock to init
  97  */
  98 static inline void drm_modeset_lock_init(struct drm_modeset_lock *lock)
  99 {
 100         ww_mutex_init(&lock->mutex, &crtc_ww_class);
 101         INIT_LIST_HEAD(&lock->head);
 102 }
 103
 104 /**
 105  * drm_modeset_lock_fini - cleanup lock
 106  * @lock: lock to cleanup
 107  */
 108 static inline void drm_modeset_lock_fini(struct drm_modeset_lock *lock)
 109 {
 110         WARN_ON(!list_empty(&lock->head));
 111 }
 112
 113 /**
 114  * drm_modeset_is_locked - equivalent to mutex_is_locked()
 115  * @lock: lock to check
 116  */
 117 static inline bool drm_modeset_is_locked(struct drm_modeset_lock *lock)
 118 {
 119         return ww_mutex_is_locked(&lock->mutex);
 120 }
 121
 122 int drm_modeset_lock(struct drm_modeset_lock *lock,
 123                 struct drm_modeset_acquire_ctx *ctx);
 124 int drm_modeset_lock_interruptible(struct drm_modeset_lock *lock,
 125                 struct drm_modeset_acquire_ctx *ctx);
 126 void drm_modeset_unlock(struct drm_modeset_lock *lock);
 127
 128 struct drm_device;
 129 struct drm_crtc;
 130 struct drm_plane;
 131
 132 void drm_modeset_lock_all(struct drm_device *dev);
 133 void drm_modeset_unlock_all(struct drm_device *dev);
 134 void drm_modeset_lock_crtc(struct drm_crtc *crtc,
 135                            struct drm_plane *plane);
 136 void drm_modeset_unlock_crtc(struct drm_crtc *crtc);
 137 void drm_warn_on_modeset_not_all_locked(struct drm_device *dev);
 138 struct drm_modeset_acquire_ctx *
 139 drm_modeset_legacy_acquire_ctx(struct drm_crtc *crtc);
 140
 141 int drm_modeset_lock_all_ctx(struct drm_device *dev,
 142                              struct drm_modeset_acquire_ctx *ctx);
 143
 144 #endif /* DRM_MODESET_LOCK_H_ */