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drm_modeset_lock.h revision 1.1 
      1 /*	$NetBSD: drm_modeset_lock.h,v 1.1 2018/08/27 01:35:00 riastradh Exp $	*/
      2 
      3 /*
      4  * Copyright (C) 2014 Red Hat
      5  * Author: Rob Clark <robdclark (at) gmail.com>
      6  *
      7  * Permission is hereby granted, free of charge, to any person obtaining a
      8  * copy of this software and associated documentation files (the "Software"),
      9  * to deal in the Software without restriction, including without limitation
     10  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
     11  * and/or sell copies of the Software, and to permit persons to whom the
     12  * Software is furnished to do so, subject to the following conditions:
     13  *
     14  * The above copyright notice and this permission notice shall be included in
     15  * all copies or substantial portions of the Software.
     16  *
     17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
     20  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
     21  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
     22  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
     23  * OTHER DEALINGS IN THE SOFTWARE.
     24  */
     25 
     26 #ifndef DRM_MODESET_LOCK_H_
     27 #define DRM_MODESET_LOCK_H_
     28 
     29 #include <linux/ww_mutex.h>
     30 
     31 struct drm_modeset_lock;
     32 
     33 /**
     34  * struct drm_modeset_acquire_ctx - locking context (see ww_acquire_ctx)
     35  * @ww_ctx: base acquire ctx
     36  * @contended: used internally for -EDEADLK handling
     37  * @locked: list of held locks
     38  * @trylock_only: trylock mode used in atomic contexts/panic notifiers
     39  *
     40  * Each thread competing for a set of locks must use one acquire
     41  * ctx.  And if any lock fxn returns -EDEADLK, it must backoff and
     42  * retry.
     43  */
     44 struct drm_modeset_acquire_ctx {
     45 
     46 	struct ww_acquire_ctx ww_ctx;
     47 
     48 	/*
     49 	 * Contended lock: if a lock is contended you should only call
     50 	 * drm_modeset_backoff() which drops locks and slow-locks the
     51 	 * contended lock.
     52 	 */
     53 	struct drm_modeset_lock *contended;
     54 
     55 	/*
     56 	 * list of held locks (drm_modeset_lock)
     57 	 */
     58 	struct list_head locked;
     59 
     60 	/*
     61 	 * Trylock mode, use only for panic handlers!
     62 	 */
     63 	bool trylock_only;
     64 };
     65 
     66 /**
     67  * struct drm_modeset_lock - used for locking modeset resources.
     68  * @mutex: resource locking
     69  * @head: used to hold it's place on state->locked list when
     70  *    part of an atomic update
     71  *
     72  * Used for locking CRTCs and other modeset resources.
     73  */
     74 struct drm_modeset_lock {
     75 	/*
     76 	 * modeset lock
     77 	 */
     78 	struct ww_mutex mutex;
     79 
     80 	/*
     81 	 * Resources that are locked as part of an atomic update are added
     82 	 * to a list (so we know what to unlock at the end).
     83 	 */
     84 	struct list_head head;
     85 };
     86 
     87 extern struct ww_class crtc_ww_class;
     88 
     89 void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
     90 		uint32_t flags);
     91 void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx);
     92 void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx);
     93 void drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx);
     94 int drm_modeset_backoff_interruptible(struct drm_modeset_acquire_ctx *ctx);
     95 
     96 /**
     97  * drm_modeset_lock_init - initialize lock
     98  * @lock: lock to init
     99  */
    100 static inline void drm_modeset_lock_init(struct drm_modeset_lock *lock)
    101 {
    102 	ww_mutex_init(&lock->mutex, &crtc_ww_class);
    103 	INIT_LIST_HEAD(&lock->head);
    104 }
    105 
    106 /**
    107  * drm_modeset_lock_fini - cleanup lock
    108  * @lock: lock to cleanup
    109  */
    110 static inline void drm_modeset_lock_fini(struct drm_modeset_lock *lock)
    111 {
    112 	WARN_ON(!list_empty(&lock->head));
    113 }
    114 
    115 /**
    116  * drm_modeset_is_locked - equivalent to mutex_is_locked()
    117  * @lock: lock to check
    118  */
    119 static inline bool drm_modeset_is_locked(struct drm_modeset_lock *lock)
    120 {
    121 	return ww_mutex_is_locked(&lock->mutex);
    122 }
    123 
    124 int drm_modeset_lock(struct drm_modeset_lock *lock,
    125 		struct drm_modeset_acquire_ctx *ctx);
    126 int drm_modeset_lock_interruptible(struct drm_modeset_lock *lock,
    127 		struct drm_modeset_acquire_ctx *ctx);
    128 void drm_modeset_unlock(struct drm_modeset_lock *lock);
    129 
    130 struct drm_device;
    131 struct drm_crtc;
    132 struct drm_plane;
    133 
    134 void drm_modeset_lock_all(struct drm_device *dev);
    135 void drm_modeset_unlock_all(struct drm_device *dev);
    136 void drm_modeset_lock_crtc(struct drm_crtc *crtc,
    137 			   struct drm_plane *plane);
    138 void drm_modeset_unlock_crtc(struct drm_crtc *crtc);
    139 void drm_warn_on_modeset_not_all_locked(struct drm_device *dev);
    140 struct drm_modeset_acquire_ctx *
    141 drm_modeset_legacy_acquire_ctx(struct drm_crtc *crtc);
    142 
    143 int drm_modeset_lock_all_crtcs(struct drm_device *dev,
    144 		struct drm_modeset_acquire_ctx *ctx);
    145 
    146 #endif /* DRM_MODESET_LOCK_H_ */
    147