path: root/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c

/**************************************************************************
 *
 * Copyright © 2011 VMware, Inc., Palo Alto, CA., USA
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 **************************************************************************/

#include <drm/drmP.h>
#include "vmwgfx_drv.h"

#define VMW_FENCE_WRAP (1 << 31)

struct vmw_fence_manager {
	int num_fence_objects;
	struct vmw_private *dev_priv;
	spinlock_t lock;
	struct list_head fence_list;
	struct work_struct work;
	u32 user_fence_size;
	u32 fence_size;
	u32 event_fence_action_size;
	bool fifo_down;
	struct list_head cleanup_list;
	uint32_t pending_actions[VMW_ACTION_MAX];
	struct mutex goal_irq_mutex;
	bool goal_irq_on; /* Protected by @goal_irq_mutex */
	bool seqno_valid; /* Protected by @lock, and may not be set to true
			     without the @goal_irq_mutex held. */
};

struct vmw_user_fence {
	struct ttm_base_object base;
	struct vmw_fence_obj fence;
};

/**
 * struct vmw_event_fence_action - fence action that delivers a drm event.
 *
 * @e: A struct drm_pending_event that controls the event delivery.
 * @action: A struct vmw_fence_action to hook up to a fence.
 * @fence: A referenced pointer to the fence to keep it alive while @action
 * hangs on it.
 * @dev: Pointer to a struct drm_device so we can access the event stuff.
 * @kref: Both @e and @action has destructors, so we need to refcount.
 * @size: Size accounted for this object.
 * @tv_sec: If non-null, the variable pointed to will be assigned
 * current time tv_sec val when the fence signals.
 * @tv_usec: Must be set if @tv_sec is set, and the variable pointed to will
 * be assigned the current time tv_usec val when the fence signals.
 */
struct vmw_event_fence_action {
	struct vmw_fence_action action;
	struct list_head fpriv_head;

	struct drm_pending_event *event;
	struct vmw_fence_obj *fence;
	struct drm_device *dev;

	uint32_t *tv_sec;
	uint32_t *tv_usec;
};

/**
 * Note on fencing subsystem usage of irqs:
 * Typically the vmw_fences_update function is called
 *
 * a) When a new fence seqno has been submitted by the fifo code.
 * b) On-demand when we have waiters. Sleeping waiters will switch on the
 * ANY_FENCE irq and call vmw_fences_update function each time an ANY_FENCE
 * irq is received. When the last fence waiter is gone, that IRQ is masked
 * away.
 *
 * In situations where there are no waiters and we don't submit any new fences,
 * fence objects may not be signaled. This is perfectly OK, since there are
 * no consumers of the signaled data, but that is NOT ok when there are fence
 * actions attached to a fence. The fencing subsystem then makes use of the
 * FENCE_GOAL irq and sets the fence goal seqno to that of the next fence
 * which has an action attached, and each time vmw_fences_update is called,
 * the subsystem makes sure the fence goal seqno is updated.
 *
 * The fence goal seqno irq is on as long as there are unsignaled fence
 * objects with actions attached to them.
 */

static void vmw_fence_obj_destroy_locked(struct kref *kref)
{
	struct vmw_fence_obj *fence =
		container_of(kref, struct vmw_fence_obj, kref);

	struct vmw_fence_manager *fman = fence->fman;
	unsigned int num_fences;

	list_del_init(&fence->head);
	num_fences = --fman->num_fence_objects;
	spin_unlock_irq(&fman->lock);
	if (fence->destroy)
		fence->destroy(fence);
	else
		kfree(fence);

	spin_lock_irq(&fman->lock);
}


/**
 * Execute signal actions on fences recently signaled.
 * This is done from a workqueue so we don't have to execute
 * signal actions from atomic context.
 */

static void vmw_fence_work_func(struct work_struct *work)
{
	struct vmw_fence_manager *fman =
		container_of(work, struct vmw_fence_manager, work);
	struct list_head list;
	struct vmw_fence_action *action, *next_action;
	bool seqno_valid;

	do {
		INIT_LIST_HEAD(&list);
		mutex_lock(&fman->goal_irq_mutex);

		spin_lock_irq(&fman->lock);
		list_splice_init(&fman->cleanup_list, &list);
		seqno_valid = fman->seqno_valid;
		spin_unlock_irq(&fman->lock);

		if (!seqno_valid && fman->goal_irq_on) {
			fman->goal_irq_on = false;
			vmw_goal_waiter_remove(fman->dev_priv);
		}
		mutex_unlock(&fman->goal_irq_mutex);

		if (list_empty(&list))
			return;

		/*
		 * At this point, only we should be able to manipulate the
		 * list heads of the actions we have on the private list.