drm/i915: Serialise with engine-pm around requests on the kernel_context

As the engine->kernel_context is used within the engine-pm barrier, we
have to be careful when emitting requests outside of the barrier, as the
strict timeline locking rules do not apply. Instead, we must ensure the
engine_park() cannot be entered as we build the request, which is
simplest by taking an explicit engine-pm wakeref around the request
construction.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191125105858.1718307-1-chris@chris-wilson.co.uk

1 files changed, 12 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/gt/selftest_engine_cs.c b/drivers/gpu/drm/i915/gt/selftest_engine_cs.c
index 5981a7b71ec9..761d81f4bd68 100644
--- a/drivers/gpu/drm/i915/gt/selftest_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/selftest_engine_cs.c
@@ -132,14 +132,18 @@ static int perf_mi_bb_start(void *arg)
 		u32 cycles[COUNT];
 		int i;
 
+		intel_engine_pm_get(engine);
+
 		batch = create_empty_batch(ce);
 		if (IS_ERR(batch)) {
 			err = PTR_ERR(batch);
+			intel_engine_pm_put(engine);
 			break;
 		}
 
 		err = i915_vma_sync(batch);
 		if (err) {
+			intel_engine_pm_put(engine);
 			i915_vma_put(batch);
 			break;
 		}
@@ -180,6 +184,7 @@ out:
 			cycles[i] = rq->hwsp_seqno[3] - rq->hwsp_seqno[2];
 		}
 		i915_vma_put(batch);
+		intel_engine_pm_put(engine);
 		if (err)
 			break;
 
@@ -251,15 +256,19 @@ static int perf_mi_noop(void *arg)
 		u32 cycles[COUNT];
 		int i;
 
+		intel_engine_pm_get(engine);
+
 		base = create_empty_batch(ce);
 		if (IS_ERR(base)) {
 			err = PTR_ERR(base);
+			intel_engine_pm_put(engine);
 			break;
 		}
 
 		err = i915_vma_sync(base);
 		if (err) {
 			i915_vma_put(base);
+			intel_engine_pm_put(engine);
 			break;
 		}
 
@@ -267,6 +276,7 @@ static int perf_mi_noop(void *arg)
 		if (IS_ERR(nop)) {
 			err = PTR_ERR(nop);
 			i915_vma_put(base);
+			intel_engine_pm_put(engine);
 			break;
 		}
 
@@ -274,6 +284,7 @@ static int perf_mi_noop(void *arg)
 		if (err) {
 			i915_vma_put(nop);
 			i915_vma_put(base);
+			intel_engine_pm_put(engine);
 			break;
 		}
 
@@ -327,6 +338,7 @@ out:
 		}
 		i915_vma_put(nop);
 		i915_vma_put(base);
+		intel_engine_pm_put(engine);
 		if (err)
 			break;