1/*
 2 * SPDX-License-Identifier: MIT
 3 *
 4 * Copyright © 2018 Intel Corporation
 5 */
 6
 7#ifndef _I915_SCHEDULER_H_
 8#define _I915_SCHEDULER_H_
 9
10#include <linux/bitops.h>
11#include <linux/list.h>
12#include <linux/kernel.h>
13
14#include "i915_scheduler_types.h"
15
16#define priolist_for_each_request(it, plist, idx) \
17	for (idx = 0; idx < ARRAY_SIZE((plist)->requests); idx++) \
18		list_for_each_entry(it, &(plist)->requests[idx], sched.link)
19
20#define priolist_for_each_request_consume(it, n, plist, idx) \
21	for (; \
22	     (plist)->used ? (idx = __ffs((plist)->used)), 1 : 0; \
23	     (plist)->used &= ~BIT(idx)) \
24		list_for_each_entry_safe(it, n, \
25					 &(plist)->requests[idx], \
26					 sched.link)
27
28void i915_sched_node_init(struct i915_sched_node *node);
29
30bool __i915_sched_node_add_dependency(struct i915_sched_node *node,
31				      struct i915_sched_node *signal,
32				      struct i915_dependency *dep,
33				      unsigned long flags);
34
35int i915_sched_node_add_dependency(struct i915_sched_node *node,
36				   struct i915_sched_node *signal);
37
38void i915_sched_node_fini(struct i915_sched_node *node);
39
40void i915_schedule(struct i915_request *request,
41		   const struct i915_sched_attr *attr);
42
43void i915_schedule_bump_priority(struct i915_request *rq, unsigned int bump);
44
45struct list_head *
46i915_sched_lookup_priolist(struct intel_engine_cs *engine, int prio);
47
48void __i915_priolist_free(struct i915_priolist *p);
49static inline void i915_priolist_free(struct i915_priolist *p)
50{
51	if (p->priority != I915_PRIORITY_NORMAL)
52		__i915_priolist_free(p);
53}
54
55static inline bool i915_scheduler_need_preempt(int prio, int active)
56{
57	/*
58	 * Allow preemption of low -> normal -> high, but we do
59	 * not allow low priority tasks to preempt other low priority
60	 * tasks under the impression that latency for low priority
61	 * tasks does not matter (as much as background throughput),
62	 * so kiss.
63	 *
64	 * More naturally we would write
65	 *	prio >= max(0, last);
66	 * except that we wish to prevent triggering preemption at the same
67	 * priority level: the task that is running should remain running
68	 * to preserve FIFO ordering of dependencies.
69	 */
70	return prio > max(I915_PRIORITY_NORMAL - 1, active);
71}
72
73#endif /* _I915_SCHEDULER_H_ */