239 lines
8.3 KiB
C
239 lines
8.3 KiB
C
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/*
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* SPDX-License-Identifier: MIT
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*
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* Copyright © 2019 Intel Corporation
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*/
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#ifndef _I915_ACTIVE_H_
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#define _I915_ACTIVE_H_
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#include <linux/lockdep.h>
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#include "i915_active_types.h"
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#include "i915_request.h"
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struct i915_request;
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struct intel_engine_cs;
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struct intel_timeline;
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/*
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* We treat requests as fences. This is not be to confused with our
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* "fence registers" but pipeline synchronisation objects ala GL_ARB_sync.
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* We use the fences to synchronize access from the CPU with activity on the
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* GPU, for example, we should not rewrite an object's PTE whilst the GPU
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* is reading them. We also track fences at a higher level to provide
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* implicit synchronisation around GEM objects, e.g. set-domain will wait
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* for outstanding GPU rendering before marking the object ready for CPU
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* access, or a pageflip will wait until the GPU is complete before showing
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* the frame on the scanout.
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*
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* In order to use a fence, the object must track the fence it needs to
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* serialise with. For example, GEM objects want to track both read and
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* write access so that we can perform concurrent read operations between
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* the CPU and GPU engines, as well as waiting for all rendering to
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* complete, or waiting for the last GPU user of a "fence register". The
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* object then embeds a #i915_active_fence to track the most recent (in
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* retirement order) request relevant for the desired mode of access.
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* The #i915_active_fence is updated with i915_active_fence_set() to
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* track the most recent fence request, typically this is done as part of
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* i915_vma_move_to_active().
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*
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* When the #i915_active_fence completes (is retired), it will
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* signal its completion to the owner through a callback as well as mark
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* itself as idle (i915_active_fence.request == NULL). The owner
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* can then perform any action, such as delayed freeing of an active
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* resource including itself.
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*/
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void i915_active_noop(struct dma_fence *fence, struct dma_fence_cb *cb);
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/**
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* __i915_active_fence_init - prepares the activity tracker for use
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* @active - the active tracker
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* @fence - initial fence to track, can be NULL
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* @func - a callback when then the tracker is retired (becomes idle),
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* can be NULL
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*
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* i915_active_fence_init() prepares the embedded @active struct for use as
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* an activity tracker, that is for tracking the last known active fence
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* associated with it. When the last fence becomes idle, when it is retired
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* after completion, the optional callback @func is invoked.
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*/
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static inline void
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__i915_active_fence_init(struct i915_active_fence *active,
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void *fence,
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dma_fence_func_t fn)
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{
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RCU_INIT_POINTER(active->fence, fence);
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active->cb.func = fn ?: i915_active_noop;
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}
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#define INIT_ACTIVE_FENCE(A) \
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__i915_active_fence_init((A), NULL, NULL)
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struct dma_fence *
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__i915_active_fence_set(struct i915_active_fence *active,
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struct dma_fence *fence);
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/**
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* i915_active_fence_set - updates the tracker to watch the current fence
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* @active - the active tracker
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* @rq - the request to watch
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*
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* i915_active_fence_set() watches the given @rq for completion. While
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* that @rq is busy, the @active reports busy. When that @rq is signaled
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* (or else retired) the @active tracker is updated to report idle.
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*/
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int __must_check
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i915_active_fence_set(struct i915_active_fence *active,
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struct i915_request *rq);
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/**
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* i915_active_fence_get - return a reference to the active fence
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* @active - the active tracker
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*
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* i915_active_fence_get() returns a reference to the active fence,
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* or NULL if the active tracker is idle. The reference is obtained under RCU,
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* so no locking is required by the caller.
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*
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* The reference should be freed with dma_fence_put().
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*/
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static inline struct dma_fence *
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i915_active_fence_get(struct i915_active_fence *active)
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{
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struct dma_fence *fence;
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rcu_read_lock();
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fence = dma_fence_get_rcu_safe(&active->fence);
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rcu_read_unlock();
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return fence;
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}
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/**
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* i915_active_fence_isset - report whether the active tracker is assigned
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* @active - the active tracker
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*
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* i915_active_fence_isset() returns true if the active tracker is currently
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* assigned to a fence. Due to the lazy retiring, that fence may be idle
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* and this may report stale information.
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*/
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static inline bool
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i915_active_fence_isset(const struct i915_active_fence *active)
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{
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return rcu_access_pointer(active->fence);
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}
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/*
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* GPU activity tracking
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*
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* Each set of commands submitted to the GPU compromises a single request that
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* signals a fence upon completion. struct i915_request combines the
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* command submission, scheduling and fence signaling roles. If we want to see
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* if a particular task is complete, we need to grab the fence (struct
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* i915_request) for that task and check or wait for it to be signaled. More
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* often though we want to track the status of a bunch of tasks, for example
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* to wait for the GPU to finish accessing some memory across a variety of
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* different command pipelines from different clients. We could choose to
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* track every single request associated with the task, but knowing that
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* each request belongs to an ordered timeline (later requests within a
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* timeline must wait for earlier requests), we need only track the
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* latest request in each timeline to determine the overall status of the
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* task.
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*
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* struct i915_active provides this tracking across timelines. It builds a
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* composite shared-fence, and is updated as new work is submitted to the task,
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* forming a snapshot of the current status. It should be embedded into the
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* different resources that need to track their associated GPU activity to
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* provide a callback when that GPU activity has ceased, or otherwise to
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* provide a serialisation point either for request submission or for CPU
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* synchronisation.
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*/
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void __i915_active_init(struct i915_active *ref,
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int (*active)(struct i915_active *ref),
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void (*retire)(struct i915_active *ref),
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unsigned long flags,
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struct lock_class_key *mkey,
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struct lock_class_key *wkey);
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/* Specialise each class of i915_active to avoid impossible lockdep cycles. */
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#define i915_active_init(ref, active, retire, flags) do { \
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static struct lock_class_key __mkey; \
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static struct lock_class_key __wkey; \
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\
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__i915_active_init(ref, active, retire, flags, &__mkey, &__wkey); \
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} while (0)
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int i915_active_add_request(struct i915_active *ref, struct i915_request *rq);
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struct dma_fence *
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i915_active_set_exclusive(struct i915_active *ref, struct dma_fence *f);
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int __i915_active_wait(struct i915_active *ref, int state);
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static inline int i915_active_wait(struct i915_active *ref)
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{
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return __i915_active_wait(ref, TASK_INTERRUPTIBLE);
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}
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int i915_sw_fence_await_active(struct i915_sw_fence *fence,
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struct i915_active *ref,
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unsigned int flags);
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int i915_request_await_active(struct i915_request *rq,
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struct i915_active *ref,
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unsigned int flags);
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#define I915_ACTIVE_AWAIT_EXCL BIT(0)
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#define I915_ACTIVE_AWAIT_ACTIVE BIT(1)
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#define I915_ACTIVE_AWAIT_BARRIER BIT(2)
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int i915_active_acquire(struct i915_active *ref);
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int i915_active_acquire_for_context(struct i915_active *ref, u64 idx);
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bool i915_active_acquire_if_busy(struct i915_active *ref);
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void i915_active_release(struct i915_active *ref);
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static inline void __i915_active_acquire(struct i915_active *ref)
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{
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GEM_BUG_ON(!atomic_read(&ref->count));
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atomic_inc(&ref->count);
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}
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static inline bool
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i915_active_is_idle(const struct i915_active *ref)
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{
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return !atomic_read(&ref->count);
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}
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void i915_active_fini(struct i915_active *ref);
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int i915_active_acquire_preallocate_barrier(struct i915_active *ref,
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struct intel_engine_cs *engine);
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void i915_active_acquire_barrier(struct i915_active *ref);
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void i915_request_add_active_barriers(struct i915_request *rq);
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void i915_active_print(struct i915_active *ref, struct drm_printer *m);
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void i915_active_unlock_wait(struct i915_active *ref);
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struct i915_active *i915_active_create(void);
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struct i915_active *i915_active_get(struct i915_active *ref);
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void i915_active_put(struct i915_active *ref);
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static inline int __i915_request_await_exclusive(struct i915_request *rq,
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struct i915_active *active)
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{
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struct dma_fence *fence;
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int err = 0;
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fence = i915_active_fence_get(&active->excl);
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if (fence) {
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err = i915_request_await_dma_fence(rq, fence);
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dma_fence_put(fence);
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}
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return err;
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}
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void i915_active_module_exit(void);
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int i915_active_module_init(void);
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#endif /* _I915_ACTIVE_H_ */
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