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Release 4.12 include/linux/seqno-fence.h

Directory: include/linux
 * seqno-fence, using a dma-buf to synchronize fencing
 * Copyright (C) 2012 Texas Instruments
 * Copyright (C) 2012 Canonical Ltd
 * Authors:
 *   Rob Clark <>
 *   Maarten Lankhorst <>
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.



#include <linux/dma-fence.h>
#include <linux/dma-buf.h>

enum seqno_fence_condition {

struct seqno_fence {
struct dma_fence base;

const struct dma_fence_ops *ops;
struct dma_buf *sync_buf;
uint32_t seqno_ofs;
enum seqno_fence_condition condition;

extern const struct dma_fence_ops seqno_fence_ops;

 * to_seqno_fence - cast a fence to a seqno_fence
 * @fence: fence to cast to a seqno_fence
 * Returns NULL if the fence is not a seqno_fence,
 * or the seqno_fence otherwise.

static inline struct seqno_fence * to_seqno_fence(struct dma_fence *fence) { if (fence->ops != &seqno_fence_ops) return NULL; return container_of(fence, struct seqno_fence, base); }


Maarten Lankhorst3697.30%150.00%
Chris Wilson12.70%150.00%

/** * seqno_fence_init - initialize a seqno fence * @fence: seqno_fence to initialize * @lock: pointer to spinlock to use for fence * @sync_buf: buffer containing the memory location to signal on * @context: the execution context this fence is a part of * @seqno_ofs: the offset within @sync_buf * @seqno: the sequence # to signal on * @cond: fence wait condition * @ops: the fence_ops for operations on this seqno fence * * This function initializes a struct seqno_fence with passed parameters, * and takes a reference on sync_buf which is released on fence destruction. * * A seqno_fence is a dma_fence which can complete in software when * enable_signaling is called, but it also completes when * (s32)((sync_buf)[seqno_ofs] - seqno) >= 0 is true * * The seqno_fence will take a refcount on the sync_buf until it's * destroyed, but actual lifetime of sync_buf may be longer if one of the * callers take a reference to it. * * Certain hardware have instructions to insert this type of wait condition * in the command stream, so no intervention from software would be needed. * This type of fence can be destroyed before completed, however a reference * on the sync_buf dma-buf can be taken. It is encouraged to re-use the same * dma-buf for sync_buf, since mapping or unmapping the sync_buf to the * device's vm can be expensive. * * It is recommended for creators of seqno_fence to call dma_fence_signal() * before destruction. This will prevent possible issues from wraparound at * time of issue vs time of check, since users can check dma_fence_is_signaled() * before submitting instructions for the hardware to wait on the fence. * However, when ops.enable_signaling is not called, it doesn't have to be * done as soon as possible, just before there's any real danger of seqno * wraparound. */
static inline void seqno_fence_init(struct seqno_fence *fence, spinlock_t *lock, struct dma_buf *sync_buf, uint32_t context, uint32_t seqno_ofs, uint32_t seqno, enum seqno_fence_condition cond, const struct dma_fence_ops *ops) { BUG_ON(!fence || !sync_buf || !ops); BUG_ON(!ops->wait || !ops->enable_signaling || !ops->get_driver_name || !ops->get_timeline_name); /* * ops is used in dma_fence_init for get_driver_name, so needs to be * initialized first */ fence->ops = ops; dma_fence_init(&fence->base, &seqno_fence_ops, lock, context, seqno); get_dma_buf(sync_buf); fence->sync_buf = sync_buf; fence->seqno_ofs = seqno_ofs; fence->condition = cond; }


Maarten Lankhorst11997.54%150.00%
Chris Wilson32.46%150.00%

#endif /* __LINUX_SEQNO_FENCE_H */

Overall Contributors

Maarten Lankhorst20995.87%150.00%
Chris Wilson94.13%150.00%
Directory: include/linux
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