[igt-dev] [PATCH i-g-t] i915/gem_ctx_isolation: Ignore the low bits of BB_OFFSET

[Chris Wilson]

On Skylake, BB_OFFSET seems to be unstable. Since this is an
offset into the batch at the time of CS execution, it should be actively
written to as we read from the register so allow it a qword of
discrepancy (since the CS should be reading in qwords). This still
allows us to detect dirt across the rest of the register field, should
that be required.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 tests/i915/gem_ctx_isolation.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/i915/gem_ctx_isolation.c b/tests/i915/gem_ctx_isolation.c
index 058cf3ec1..78a244382 100644
--- a/tests/i915/gem_ctx_isolation.c
+++ b/tests/i915/gem_ctx_isolation.c
@@ -96,7 +96,7 @@ static const struct named_register {
 	{ "GPGPU_THREADS_DISPATCHED", GEN8, RCS0, 0x2290, 2 },
 	{ "PS_INVOCATION_COUNT_1", GEN8, RCS0, 0x22f0, 2 },
 	{ "PS_DEPTH_COUNT_1", GEN8, RCS0, 0x22f8, 2 },
-	{ "BB_OFFSET", GEN8, RCS0, 0x2158 },
+	{ "BB_OFFSET", GEN8, RCS0, 0x2158, .ignore_bits = 0x7 },
 	{ "MI_PREDICATE_RESULT_1", GEN8, RCS0, 0x241c },
 	{ "CS_GPR", GEN8, RCS0, 0x2600, 32 },
 	{ "OA_CTX_CONTROL", GEN8, RCS0, 0x2360 },
-- 
2.20.1