Home | History | Annotate | Line # | Download | only in drm
drm_modeset_lock.h revision 1.4 
      1 /*	$NetBSD: drm_modeset_lock.h,v 1.4 2018/08/27 14:39:59 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 #include <asm/bug.h>
     31 
     32 struct drm_modeset_lock;
     33 
     34 /**
     35  * struct drm_modeset_acquire_ctx - locking context (see ww_acquire_ctx)
     36  * @ww_ctx: base acquire ctx
     37  * @contended: used internally for -EDEADLK handling
     38  * @locked: list of held locks
     39  * @trylock_only: trylock mode used in atomic contexts/panic notifiers
     40  *
     41  * Each thread competing for a set of locks must use one acquire
     42  * ctx.  And if any lock fxn returns -EDEADLK, it must backoff and
     43  * retry.
     44  */
     45 struct drm_modeset_acquire_ctx {
     46 
     47 	struct ww_acquire_ctx ww_ctx;
     48 
     49 	/*
     50 	 * Contended lock: if a lock is contended you should only call
     51 	 * drm_modeset_backoff() which drops locks and slow-locks the
     52 	 * contended lock.
     53 	 */
     54 	struct drm_modeset_lock *contended;
     55 
     56 	/*
     57 	 * list of held locks (drm_modeset_lock)
     58 	 */
     59 	struct list_head locked;
     60 
     61 	/*
     62 	 * Trylock mode, use only for panic handlers!
     63 	 */
     64 	bool trylock_only;
     65 };
     66 
     67 /**
     68  * struct drm_modeset_lock - used for locking modeset resources.
     69  * @mutex: resource locking
     70  * @head: used to hold it's place on state->locked list when
     71  *    part of an atomic update
     72  *
     73  * Used for locking CRTCs and other modeset resources.
     74  */
     75 struct drm_modeset_lock {
     76 	/*
     77 	 * modeset lock
     78 	 */
     79 	struct ww_mutex mutex;
     80 
     81 	/*
     82 	 * Resources that are locked as part of an atomic update are added
     83 	 * to a list (so we know what to unlock at the end).
     84 	 */
     85 	struct list_head head;
     86 };
     87 
     88 extern struct ww_class crtc_ww_class;
     89 
     90 void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
     91 		uint32_t flags);
     92 void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx);
     93 void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx);
     94 void drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx);
     95 int drm_modeset_backoff_interruptible(struct drm_modeset_acquire_ctx *ctx);
     96 
     97 /**
     98  * drm_modeset_lock_init - initialize lock
     99  * @lock: lock to init
    100  */
    101 static inline void drm_modeset_lock_init(struct drm_modeset_lock *lock)
    102 {
    103 	ww_mutex_init(&lock->mutex, &crtc_ww_class);
    104 	INIT_LIST_HEAD(&lock->head);
    105 }
    106 
    107 /**
    108  * drm_modeset_lock_fini - cleanup lock
    109  * @lock: lock to cleanup
    110  */
    111 static inline void drm_modeset_lock_fini(struct drm_modeset_lock *lock)
    112 {
    113 	WARN_ON(!list_empty(&lock->head));
    114 	ww_mutex_destroy(&lock->mutex);
    115 }
    116 
    117 /**
    118  * drm_modeset_is_locked - equivalent to mutex_is_locked()
    119  * @lock: lock to check
    120  */
    121 static inline bool drm_modeset_is_locked(struct drm_modeset_lock *lock)
    122 {
    123 	return ww_mutex_is_locked(&lock->mutex);
    124 }
    125 
    126 int drm_modeset_lock(struct drm_modeset_lock *lock,
    127 		struct drm_modeset_acquire_ctx *ctx);
    128 int drm_modeset_lock_interruptible(struct drm_modeset_lock *lock,
    129 		struct drm_modeset_acquire_ctx *ctx);
    130 void drm_modeset_unlock(struct drm_modeset_lock *lock);
    131 
    132 struct drm_device;
    133 struct drm_crtc;
    134 struct drm_plane;
    135 
    136 void drm_modeset_lock_all(struct drm_device *dev);
    137 void drm_modeset_unlock_all(struct drm_device *dev);
    138 void drm_modeset_lock_crtc(struct drm_crtc *crtc,
    139 			   struct drm_plane *plane);
    140 void drm_modeset_unlock_crtc(struct drm_crtc *crtc);
    141 void drm_warn_on_modeset_not_all_locked(struct drm_device *dev);
    142 struct drm_modeset_acquire_ctx *
    143 drm_modeset_legacy_acquire_ctx(struct drm_crtc *crtc);
    144 
    145 int drm_modeset_lock_all_crtcs(struct drm_device *dev,
    146 		struct drm_modeset_acquire_ctx *ctx);
    147 
    148 #endif /* DRM_MODESET_LOCK_H_ */
    149