[PATCH v2 2/2] drm/tests: Add a unit test for range bias allocation

[Arunpravin Paneer Selvam]

Allocate cleared blocks in the bias range when the DRM
buddy's clear avail is zero. This will validate the bias
range allocation in scenarios like system boot when no
cleared blocks are available and exercise the fallback
path too. The resulting blocks should always be dirty.

Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam at amd.com>
---
 drivers/gpu/drm/tests/drm_buddy_test.c | 35 ++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/drivers/gpu/drm/tests/drm_buddy_test.c b/drivers/gpu/drm/tests/drm_buddy_test.c
index e3b50e240d36..a194f271bc55 100644
--- a/drivers/gpu/drm/tests/drm_buddy_test.c
+++ b/drivers/gpu/drm/tests/drm_buddy_test.c
@@ -26,6 +26,8 @@ static void drm_test_buddy_alloc_range_bias(struct kunit *test)
 	u32 mm_size, ps, bias_size, bias_start, bias_end, bias_rem;
 	DRM_RND_STATE(prng, random_seed);
 	unsigned int i, count, *order;
+	struct drm_buddy_block *block;
+	unsigned long flags;
 	struct drm_buddy mm;
 	LIST_HEAD(allocated);
 
@@ -222,6 +224,39 @@ static void drm_test_buddy_alloc_range_bias(struct kunit *test)
 
 	drm_buddy_free_list(&mm, &allocated, 0);
 	drm_buddy_fini(&mm);
+
+	/*
+	 * Allocate cleared blocks in the bias range when the DRM buddy's clear avail is
+	 * zero. This will validate the bias range allocation in scenarios like system boot
+	 * when no cleared blocks are available and exercise the fallback path too. The resulting
+	 * blocks should always be dirty.
+	 */
+
+	KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_init(&mm, mm_size, ps),
+			       "buddy_init failed\n");
+	mm.clear_avail = 0;
+
+	bias_start = round_up(prandom_u32_state(&prng) % (mm_size - ps), ps);
+	bias_end = round_up(bias_start + prandom_u32_state(&prng) % (mm_size - bias_start), ps);
+	bias_end = max(bias_end, bias_start + ps);
+	bias_rem = bias_end - bias_start;
+
+	flags = DRM_BUDDY_CLEAR_ALLOCATION | DRM_BUDDY_RANGE_ALLOCATION;
+	u32 size = max(round_up(prandom_u32_state(&prng) % bias_rem, ps), ps);
+
+	KUNIT_ASSERT_FALSE_MSG(test,
+			       drm_buddy_alloc_blocks(&mm, bias_start,
+						      bias_end, size, ps,
+						      &allocated,
+						      flags),
+			       "buddy_alloc failed with bias(%x-%x), size=%u, ps=%u\n",
+			       bias_start, bias_end, size, ps);
+
+	list_for_each_entry(block, &allocated, link)
+		KUNIT_EXPECT_EQ(test, drm_buddy_block_is_clear(block), false);
+
+	drm_buddy_free_list(&mm, &allocated, 0);
+	drm_buddy_fini(&mm);
 }
 
 static void drm_test_buddy_alloc_clear(struct kunit *test)
-- 
2.25.1