drm/i915: Keep rings pinned while the context is active

Remember to keep the rings pinned as well as the context image until the
GPU is no longer active.

v2: Introduce a ring->pin_count primarily to hide the
mock_ring that doesn't fit into the normal GGTT vma picture.

v3: Order is important in teardown, ringbuffer submission needs to drop
the pin count on the engine->kernel_context before it can gleefully free
its ring.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110946
Fixes: ce476c80b8bf ("drm/i915: Keep contexts pinned until after the next kernel context switch")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190619170135.15281-1-chris@chris-wilson.co.uk

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/gt/mock_engine.c b/drivers/gpu/drm/i915/gt/mock_engine.c
index 086801b51441..486c6953dcb1 100644
--- a/drivers/gpu/drm/i915/gt/mock_engine.c
+++ b/drivers/gpu/drm/i915/gt/mock_engine.c
@@ -66,6 +66,7 @@ static struct intel_ring *mock_ring(struct intel_engine_cs *engine)
 	ring->base.effective_size = sz;
 	ring->base.vaddr = (void *)(ring + 1);
 	ring->base.timeline = &ring->timeline;
+	atomic_set(&ring->base.pin_count, 1);
 
 	INIT_LIST_HEAD(&ring->base.request_list);
 	intel_ring_update_space(&ring->base);