[RFC PATCH i-g-t v3 3/4] tests/gem_exec_reloc: Calculate softpin offsets from actual page size

[Janusz Krzysztofik]

From: Janusz Krzysztofik <janusz.krzysztofik at intel.com>

The basic-range subtest assumes 4kB page size while calculating softpin
offsets.  On future backends with possibly larger minimum page sizes
a half of calculated offsets to be tested may be incorrectly detected
as occupied by other users and skiped, significantly distoring the
intended test pattern.

Replace hardcoded constants corresponding to the assumed 4kB page size
with variables initialized with actual minimum page size and order.

v2: Simplify the code by reversing the size->order conversion,
  - drop irrelevant modifications of requested object sizes.
v3: Initialize page size order with an actual minimum returned by a new
    helper (inspired by Chris).

Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik at intel.com>
Cc: Katarzyna Dec <katarzyna.dec at intel.com>
Cc: Stuart Summers <stuart.summers at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
---
 tests/i915/gem_exec_reloc.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/tests/i915/gem_exec_reloc.c b/tests/i915/gem_exec_reloc.c
index 61f8b755..5e7df8ed 100644
--- a/tests/i915/gem_exec_reloc.c
+++ b/tests/i915/gem_exec_reloc.c
@@ -510,14 +510,16 @@ static void basic_range(int fd, unsigned flags)
 	uint64_t gtt_size = gem_aperture_size(fd);
 	const uint32_t bbe = MI_BATCH_BUFFER_END;
 	igt_spin_t *spin = NULL;
+	int page_order = gem_min_page_size_order(fd);
+	uint64_t page_size = 1ull << page_order;
 	int count, n;
 
 	igt_require(gem_has_softpin(fd));
 
-	for (count = 12; gtt_size >> (count + 1); count++)
+	for (count = page_order; gtt_size >> (count + 1); count++)
 		;
 
-	count -= 12;
+	count -= page_order;
 
 	memset(obj, 0, sizeof(obj));
 	memset(reloc, 0, sizeof(reloc));
@@ -526,7 +528,7 @@ static void basic_range(int fd, unsigned flags)
 	n = 0;
 	for (int i = 0; i <= count; i++) {
 		obj[n].handle = gem_create(fd, 4096);
-		obj[n].offset = (1ull << (i + 12)) - 4096;
+		obj[n].offset = (1ull << (i + page_order)) - page_size;
 		obj[n].offset = gen8_canonical_addr(obj[n].offset);
 		obj[n].flags = EXEC_OBJECT_PINNED | EXEC_OBJECT_SUPPORTS_48B_ADDRESS;
 		gem_write(fd, obj[n].handle, 0, &bbe, sizeof(bbe));
@@ -546,7 +548,7 @@ static void basic_range(int fd, unsigned flags)
 	}
 	for (int i = 1; i < count; i++) {
 		obj[n].handle = gem_create(fd, 4096);
-		obj[n].offset = 1ull << (i + 12);
+		obj[n].offset = 1ull << (i + page_order);
 		obj[n].offset = gen8_canonical_addr(obj[n].offset);
 		obj[n].flags = EXEC_OBJECT_PINNED | EXEC_OBJECT_SUPPORTS_48B_ADDRESS;
 		gem_write(fd, obj[n].handle, 0, &bbe, sizeof(bbe));
-- 
2.21.0