1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright © 2020 Intel Corporation
4 */
5
6static struct intel_ring *mock_ring(unsigned long sz)
7{
8 struct intel_ring *ring;
9
10 ring = kzalloc(size: sizeof(*ring) + sz, GFP_KERNEL);
11 if (!ring)
12 return NULL;
13
14 kref_init(kref: &ring->ref);
15 ring->size = sz;
16 ring->wrap = BITS_PER_TYPE(ring->size) - ilog2(sz);
17 ring->effective_size = sz;
18 ring->vaddr = (void *)(ring + 1);
19 atomic_set(v: &ring->pin_count, i: 1);
20
21 intel_ring_update_space(ring);
22
23 return ring;
24}
25
26static void mock_ring_free(struct intel_ring *ring)
27{
28 kfree(objp: ring);
29}
30
31static int check_ring_direction(struct intel_ring *ring,
32 u32 next, u32 prev,
33 int expected)
34{
35 int result;
36
37 result = intel_ring_direction(ring, next, prev);
38 if (result < 0)
39 result = -1;
40 else if (result > 0)
41 result = 1;
42
43 if (result != expected) {
44 pr_err("intel_ring_direction(%u, %u):%d != %d\n",
45 next, prev, result, expected);
46 return -EINVAL;
47 }
48
49 return 0;
50}
51
52static int check_ring_step(struct intel_ring *ring, u32 x, u32 step)
53{
54 u32 prev = x, next = intel_ring_wrap(ring, pos: x + step);
55 int err = 0;
56
57 err |= check_ring_direction(ring, next, prev: next, expected: 0);
58 err |= check_ring_direction(ring, next: prev, prev, expected: 0);
59 err |= check_ring_direction(ring, next, prev, expected: 1);
60 err |= check_ring_direction(ring, next: prev, prev: next, expected: -1);
61
62 return err;
63}
64
65static int check_ring_offset(struct intel_ring *ring, u32 x, u32 step)
66{
67 int err = 0;
68
69 err |= check_ring_step(ring, x, step);
70 err |= check_ring_step(ring, x: intel_ring_wrap(ring, pos: x + 1), step);
71 err |= check_ring_step(ring, x: intel_ring_wrap(ring, pos: x - 1), step);
72
73 return err;
74}
75
76static int igt_ring_direction(void *dummy)
77{
78 struct intel_ring *ring;
79 unsigned int half = 2048;
80 int step, err = 0;
81
82 ring = mock_ring(sz: 2 * half);
83 if (!ring)
84 return -ENOMEM;
85
86 GEM_BUG_ON(ring->size != 2 * half);
87
88 /* Precision of wrap detection is limited to ring->size / 2 */
89 for (step = 1; step < half; step <<= 1) {
90 err |= check_ring_offset(ring, x: 0, step);
91 err |= check_ring_offset(ring, x: half, step);
92 }
93 err |= check_ring_step(ring, x: 0, step: half - 64);
94
95 /* And check unwrapped handling for good measure */
96 err |= check_ring_offset(ring, x: 0, step: 2 * half + 64);
97 err |= check_ring_offset(ring, x: 3 * half, step: 1);
98
99 mock_ring_free(ring);
100 return err;
101}
102
103int intel_ring_mock_selftests(void)
104{
105 static const struct i915_subtest tests[] = {
106 SUBTEST(igt_ring_direction),
107 };
108
109 return i915_subtests(tests, NULL);
110}
111

source code of linux/drivers/gpu/drm/i915/gt/selftest_ring.c