[PATCH] drm/i915: fix whitelist selftests with readonly registers

Chris Wilson
2019-06-29T13:14:11Z

From: Lionel Landwerlin <lionel.g.landwerlin@intel.com>

When a register is readonly there is not much we can tell about its
value (apart from its default value?). This can be covered by tests
exercising the value of the register from userspace.

For PS_INVOCATION_COUNT we've got the following piglit tests :

KHR-GL45.pipeline_statistics_query_tests_ARB.functional_fragment_shader_invocations

Vulkan CTS tests :

dEQP-VK.query_pool.statistics_query.fragment_shader_invocations.*

v2: Use a local to shrink under 80cols.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Fixes: 86554f48e511 ("drm/i915/selftests: Verify whitelist of context registers")
Tested-by: Anuj Phogat <anuj.phogat@gmail.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
Fixes is a bit much, since the test is still very much nerfed and not
complemented by a test for read-only non-priv registers...
-Chris
---
drivers/gpu/drm/i915/gt/selftest_workarounds.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/selftest_workarounds.c b/drivers/gpu/drm/i915/gt/selftest_workarounds.c
index f12cb20fe785..b933d831eeb1 100644
--- a/drivers/gpu/drm/i915/gt/selftest_workarounds.c
+++ b/drivers/gpu/drm/i915/gt/selftest_workarounds.c
@@ -926,7 +926,12 @@ check_whitelisted_registers(struct intel_engine_cs *engine,

err = 0;
for (i = 0; i < engine->whitelist.count; i++) {
- if (!fn(engine, a[i], b[i], engine->whitelist.list[i].reg))
+ const struct i915_wa *wa = &engine->whitelist.list[i];
+
+ if (i915_mmio_reg_offset(wa->reg) & RING_FORCE_TO_NONPRIV_RD)
+ continue;
+
+ if (!fn(engine, a[i], b[i], wa->reg))
err = -EINVAL;
}

--
2.20.1