[Intel-gfx] [PATCH 07/53] drm/i915: Early alloc request in execbuff

[John.C.Harrison at Intel.com]

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

Start of explicit request management in the execbuffer code path. This patch
adds a call to allocate a request structure before all the actual hardware work
is done. Thus guaranteeing that all that work is tagged by a known request. At
present, nothing further is done with the request, the rest comes later in the
series.

The only noticable change is that failure to get a request (e.g. due to lack of
memory) will be caught earlier in the sequence. It now occurs right at the start
before any un-undoable work has been done.

For: VIZ-5115
Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
---
 drivers/gpu/drm/i915/i915_gem_execbuffer.c |   13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index ca85803..61471e9 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1356,7 +1356,7 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
 	const u32 ctx_id = i915_execbuffer2_get_context_id(*args);
 	u32 dispatch_flags;
 	int ret;
-	bool need_relocs;
+	bool need_relocs, batch_pinned = false;
 
 	if (!i915_gem_check_execbuffer(args))
 		return -EINVAL;
@@ -1525,10 +1525,16 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
 		if (ret)
 			goto err;
 
+		batch_pinned = true;
 		params->batch_obj_vm_offset = i915_gem_obj_ggtt_offset(batch_obj);
 	} else
 		params->batch_obj_vm_offset = i915_gem_obj_offset(batch_obj, vm);
 
+	/* Allocate a request for this batch buffer nice and early. */
+	ret = dev_priv->gt.alloc_request(ring, ctx);
+	if (ret)
+		goto err;
+
 	/*
 	 * Save assorted stuff away to pass through to *_submission().
 	 * NB: This data should be 'persistent' and not local as it will
@@ -1544,15 +1550,16 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
 
 	ret = dev_priv->gt.do_execbuf(params, args, &eb->vmas);
 
+err:
 	/*
 	 * FIXME: We crucially rely upon the active tracking for the (ppgtt)
 	 * batch vma for correctness. For less ugly and less fragility this
 	 * needs to be adjusted to also track the ggtt batch vma properly as
 	 * active.
 	 */
-	if (dispatch_flags & I915_DISPATCH_SECURE)
+	if (batch_pinned)
 		i915_gem_object_ggtt_unpin(batch_obj);
-err:
+
 	/* the request owns the ref now */
 	i915_gem_context_unreference(ctx);
 	eb_destroy(eb);
-- 
1.7.9.5