During the reset of ring submission, we first stop the engine by
clearing the HEAD/TAIL and marking the ring as disabled. However, it
would be safer to disable the ring (after emptying) before resetting the
HEAD/TAIL.
Suggested-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_ring_submission.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
index 44159595d909..8a5314b97b04 100644
--- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
@@ -301,13 +301,17 @@ static void xcs_sanitize(struct intel_engine_cs *engine)
static bool stop_ring(struct intel_engine_cs *engine)
{
+ /* Empty the ring by skipping to the end */
ENGINE_WRITE_FW(engine, RING_HEAD, ENGINE_READ_FW(engine, RING_TAIL));
-
- ENGINE_WRITE_FW(engine, RING_HEAD, 0);
- ENGINE_WRITE_FW(engine, RING_TAIL, 0);
+ ENGINE_POSTING_READ(engine, RING_HEAD);
/* The ring must be empty before it is disabled */
ENGINE_WRITE_FW(engine, RING_CTL, 0);
+ ENGINE_POSTING_READ(engine, RING_CTL);
+
+ /* Then reset the disabled ring */
+ ENGINE_WRITE_FW(engine, RING_HEAD, 0);
+ ENGINE_WRITE_FW(engine, RING_TAIL, 0);
return (ENGINE_READ_FW(engine, RING_HEAD) & HEAD_ADDR) == 0;
}
--
2.20.1
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