[Intel-gfx] [RFC 15/39] drm/i915: Keep the reserved space mechanism happy

[John.C.Harrison at Intel.com]

From: John Harrison <John.C.Harrison at Intel.com>

Ring space is reserved when constructing a request to ensure that the
subsequent 'add_request()' call cannot fail due to waiting for space
on a busy or broken GPU. However, the scheduler jumps in to the middle
of the execbuffer process between request creation and request
submission. Thus it needs to cancel the reserved space when the
request is simply added to the scheduler's queue and not yet
submitted. Similarly, it needs to re-reserve the space when it finally
does want to send the batch buffer to the hardware.

For: VIZ-1587
Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
---
 drivers/gpu/drm/i915/i915_gem_execbuffer.c |  7 +++++++
 drivers/gpu/drm/i915/i915_scheduler.c      |  4 ++++
 drivers/gpu/drm/i915/intel_lrc.c           | 13 +++++++++++--
 3 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 364e9cc..75d018d 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1317,6 +1317,10 @@ int i915_gem_ringbuffer_submission_final(struct i915_execbuffer_params *params)
 	/* The mutex must be acquired before calling this function */
 	BUG_ON(!mutex_is_locked(&params->dev->struct_mutex));
 
+	ret = intel_ring_reserve_space(params->request);
+	if (ret)
+		return ret;
+
 	intel_runtime_pm_get(dev_priv);
 
 	/*
@@ -1392,6 +1396,9 @@ error:
 	 */
 	intel_runtime_pm_put(dev_priv);
 
+	if (ret)
+		intel_ring_reserved_space_cancel(params->request->ringbuf);
+
 	return ret;
 }
 
diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
index 3494fd5..e145829 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -95,6 +95,8 @@ int i915_scheduler_queue_execbuffer(struct i915_scheduler_queue_entry *qe)
 
 		qe->scheduler_index = scheduler->index++;
 
+		intel_ring_reserved_space_cancel(qe->params.request->ringbuf);
+
 		scheduler->flags[qe->params.ring->id] |= i915_sf_submitting;
 		ret = dev_priv->gt.execbuf_final(&qe->params);
 		scheduler->flags[qe->params.ring->id] &= ~i915_sf_submitting;
@@ -126,6 +128,8 @@ int i915_scheduler_queue_execbuffer(struct i915_scheduler_queue_entry *qe)
 	node->stamp  = stamp;
 	i915_gem_request_reference(node->params.request);
 
+	intel_ring_reserved_space_cancel(node->params.request->ringbuf);
+
 	BUG_ON(node->params.request->scheduler_qe);
 	node->params.request->scheduler_qe = node;
 
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index a8c78ec..76d5023 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -908,13 +908,17 @@ int intel_execlists_submission_final(struct i915_execbuffer_params *params)
 	/* The mutex must be acquired before calling this function */
 	BUG_ON(!mutex_is_locked(&params->dev->struct_mutex));
 
+	ret = intel_logical_ring_reserve_space(params->request);
+	if (ret)
+		return ret;
+
 	/*
 	 * Unconditionally invalidate gpu caches and ensure that we do flush
 	 * any residual writes from the previous batch.
 	 */
 	ret = logical_ring_invalidate_all_caches(params->request);
 	if (ret)
-		return ret;
+		goto err;
 
 	if (ring == &dev_priv->ring[RCS] &&
 	    params->instp_mode != dev_priv->relative_constants_mode) {
@@ -938,13 +942,18 @@ int intel_execlists_submission_final(struct i915_execbuffer_params *params)
 
 	ret = ring->emit_bb_start(params->request, exec_start, params->dispatch_flags);
 	if (ret)
-		return ret;
+		goto err;
 
 	trace_i915_gem_ring_dispatch(params->request, params->dispatch_flags);
 
 	i915_gem_execbuffer_retire_commands(params);
 
 	return 0;
+
+err:
+	intel_ring_reserved_space_cancel(params->request->ringbuf);
+
+	return ret;
 }
 
 void intel_execlists_retire_requests(struct intel_engine_cs *ring)
-- 
1.9.1