[Intel-gfx] [PATCH] drm/i915/perf: Assert locking for i915_init_oa_perf_state()

[Chris Wilson]

We use the context->pin_mutex to serialise updates to the OA config and
the registers values written into each new context. Document this
relationship and assert we do hold the context->pin_mutex as used by
gen8_configure_all_contexts() to serialise updates to the OA config
itself.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
---
 drivers/gpu/drm/i915/i915_perf.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index 2c9f46e12622..c1b764233761 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -2305,6 +2305,9 @@ void i915_oa_init_reg_state(struct intel_engine_cs *engine,
 {
 	struct i915_perf_stream *stream;
 
+	/* perf.exclusive_stream serialised by gen8_configure_all_contexts() */
+	lockdep_assert_held(&ce->pin_mutex);
+
 	if (engine->class != RENDER_CLASS)
 		return;
 
-- 
2.23.0