drm/i915: Keep the reserved space mechanism happy

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.

v3: Updated to use locally cached request pointer.

v5: Updated due to changes to earlier patches in series - for runtime
PM calls and splitting bypass mode into a separate function.

For: VIZ-1587
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>

3 files changed, 29 insertions, 8 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 1565ee5631d7..1e47fa450d0c 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1299,18 +1299,22 @@ int i915_gem_ringbuffer_submission_final(struct i915_execbuffer_params *params)
 	/* The mutex must be acquired before calling this function */
 	WARN_ON(!mutex_is_locked(&params->dev->struct_mutex));
 
+	ret = intel_ring_reserve_space(req);
+	if (ret)
+		goto error;
+
 	/*
 	 * Unconditionally invalidate gpu caches and ensure that we do flush
 	 * any residual writes from the previous batch.
 	 */
 	ret = intel_ring_invalidate_all_caches(req);
 	if (ret)
-		return ret;
+		goto error;
 
 	/* Switch to the correct context for the batch */
 	ret = i915_switch_context(req);
 	if (ret)
-		return ret;
+		goto error;
 
 	WARN(params->ctx->ppgtt && params->ctx->ppgtt->pd_dirty_rings & (1<<engine->id),
 	     "%s didn't clear reload\n", engine->name);
@@ -1319,7 +1323,7 @@ int i915_gem_ringbuffer_submission_final(struct i915_execbuffer_params *params)
 	    params->instp_mode != dev_priv->relative_constants_mode) {
 		ret = intel_ring_begin(req, 4);
 		if (ret)
-			return ret;
+			goto error;
 
 		intel_ring_emit(engine, MI_NOOP);
 		intel_ring_emit(engine, MI_LOAD_REGISTER_IMM(1));
@@ -1333,7 +1337,7 @@ int i915_gem_ringbuffer_submission_final(struct i915_execbuffer_params *params)
 	if (params->args_flags & I915_EXEC_GEN7_SOL_RESET) {
 		ret = i915_reset_gen7_sol_offsets(params->dev, req);
 		if (ret)
-			return ret;
+			goto error;
 	}
 
 	exec_len   = params->args_batch_len;
@@ -1347,13 +1351,17 @@ int i915_gem_ringbuffer_submission_final(struct i915_execbuffer_params *params)
 					  exec_start, exec_len,
 					  params->dispatch_flags);
 	if (ret)
-		return ret;
+		goto error;
 
 	trace_i915_gem_ring_dispatch(req, params->dispatch_flags);
 
 	i915_gem_execbuffer_retire_commands(params);
 
-	return 0;
+error:
+	if (ret)
+		intel_ring_reserved_space_cancel(req->ringbuf);
+
+	return ret;
 }
 
 /**
diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
index 2dc5597941ea..2fb3f52466dc 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -519,6 +519,8 @@ static int i915_scheduler_queue_execbuffer_bypass(struct i915_scheduler_queue_en
 	struct i915_scheduler *scheduler = dev_priv->scheduler;
 	int ret;
 
+	intel_ring_reserved_space_cancel(qe->params.request->ringbuf);
+
 	scheduler->flags[qe->params.engine->id] |= I915_SF_SUBMITTING;
 	ret = dev_priv->gt.execbuf_final(&qe->params);
 	scheduler->flags[qe->params.engine->id] &= ~I915_SF_SUBMITTING;
@@ -584,6 +586,8 @@ int i915_scheduler_queue_execbuffer(struct i915_scheduler_queue_entry *qe)
 	node->stamp  = jiffies;
 	i915_gem_request_reference(node->params.request);
 
+	intel_ring_reserved_space_cancel(node->params.request->ringbuf);
+
 	WARN_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 6bf0e3f21342..0a4ef615955a 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1010,13 +1010,17 @@ int intel_execlists_submission_final(struct i915_execbuffer_params *params)
 	/* The mutex must be acquired before calling this function */
 	WARN_ON(!mutex_is_locked(&params->dev->struct_mutex));
 
+	ret = intel_logical_ring_reserve_space(req);
+	if (ret)
+		goto err;
+
 	/*
 	 * Unconditionally invalidate gpu caches and ensure that we do flush
 	 * any residual writes from the previous batch.
 	 */
 	ret = logical_ring_invalidate_all_caches(req);
 	if (ret)
-		return ret;
+		goto err;
 
 	if (engine == &dev_priv->engine[RCS] &&
 	    params->instp_mode != dev_priv->relative_constants_mode) {
@@ -1038,13 +1042,18 @@ int intel_execlists_submission_final(struct i915_execbuffer_params *params)
 
 	ret = engine->emit_bb_start(req, exec_start, params->dispatch_flags);
 	if (ret)
-		return ret;
+		goto err;
 
 	trace_i915_gem_ring_dispatch(req, 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 *engine)