sys/dev/drm/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  * 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  *
  37  * Each thread competing for a set of locks must use one acquire
  38  * ctx.  And if any lock fxn returns -EDEADLK, it must backoff and
  39  * retry.
  40  */
  41 struct drm_modeset_acquire_ctx {
  42
  43         struct ww_acquire_ctx ww_ctx;
  44
  45         /**
  46          * Contended lock: if a lock is contended you should only call
  47          * drm_modeset_backoff() which drops locks and slow-locks the
  48          * contended lock.
  49          */
  50         struct drm_modeset_lock *contended;
  51
  52         /**
  53          * list of held locks (drm_modeset_lock)
  54          */
  55         struct list_head locked;
  56 };
  57
  58 /**
  59  * drm_modeset_lock - used for locking modeset resources.
  60  * @mutex: resource locking
  61  * @head: used to hold it's place on state->locked list when
  62  *    part of an atomic update
  63  *
  64  * Used for locking CRTCs and other modeset resources.
  65  */
  66 struct drm_modeset_lock {
  67         /**
  68          * modeset lock
  69          */
  70         struct ww_mutex mutex;
  71
  72         /**
  73          * Resources that are locked as part of an atomic update are added
  74          * to a list (so we know what to unlock at the end).
  75          */
  76         struct list_head head;
  77 };
  78
  79 extern struct ww_class crtc_ww_class;
  80
  81 void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
  82                 uint32_t flags);
  83 void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx);
  84 void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx);
  85 void drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx);
  86 int drm_modeset_backoff_interruptible(struct drm_modeset_acquire_ctx *ctx);
  87
  88 /**
  89  * drm_modeset_lock_init - initialize lock
  90  * @lock: lock to init
  91  */
  92 static inline void drm_modeset_lock_init(struct drm_modeset_lock *lock)
  93 {
  94         ww_mutex_init(&lock->mutex, &crtc_ww_class);
  95         INIT_LIST_HEAD(&lock->head);
  96 }
  97
  98 /**
  99  * drm_modeset_lock_fini - cleanup lock
 100  * @lock: lock to cleanup
 101  */
 102 static inline void drm_modeset_lock_fini(struct drm_modeset_lock *lock)
 103 {
 104         WARN_ON(!list_empty(&lock->head));
 105 }
 106
 107 /**
 108  * drm_modeset_is_locked - equivalent to mutex_is_locked()
 109  * @lock: lock to check
 110  */
 111 static inline bool drm_modeset_is_locked(struct drm_modeset_lock *lock)
 112 {
 113         return ww_mutex_is_locked(&lock->mutex);
 114 }
 115
 116 int drm_modeset_lock(struct drm_modeset_lock *lock,
 117                 struct drm_modeset_acquire_ctx *ctx);
 118 int drm_modeset_lock_interruptible(struct drm_modeset_lock *lock,
 119                 struct drm_modeset_acquire_ctx *ctx);
 120 void drm_modeset_unlock(struct drm_modeset_lock *lock);
 121
 122 struct drm_device;
 123 int drm_modeset_lock_all_crtcs(struct drm_device *dev,
 124                 struct drm_modeset_acquire_ctx *ctx);
 125
 126 #endif /* DRM_MODESET_LOCK_H_ */