drm/i915: simplify allocation of driver-internal requests

There are a number of places where the driver needs a request, but isn't
working on behalf of any specific user or in a specific context. At
present, we associate them with the per-engine default context. A future
patch will abolish those per-engine context pointers; but we can already
eliminate a lot of the references to them, just by making the allocator
allow NULL as a shorthand for "an appropriate context for this ring",
which will mean that the callers don't need to know anything about how
the "appropriate context" is found (e.g. per-ring vs per-device, etc).

So this patch renames the existing i915_gem_request_alloc(), and makes
it local (static inline), and replaces it with a wrapper that provides
a default if the context is NULL, and also has a nicer calling
convention (doesn't require a pointer to an output parameter). Then we
change all callers to use the new convention:
OLD:
	err = i915_gem_request_alloc(ring, user_ctx, &req);
	if (err) ...
NEW:
	req = i915_gem_request_alloc(ring, user_ctx);
	if (IS_ERR(req)) ...
OLD:
	err = i915_gem_request_alloc(ring, ring->default_context, &req);
	if (err) ...
NEW:
	req = i915_gem_request_alloc(ring, NULL);
	if (IS_ERR(req)) ...

v4:	Rebased

Signed-off-by: Dave Gordon <david.s.gordon@intel.com>
Reviewed-by: Nick Hoath <nicholas.hoath@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1453230175-19330-2-git-send-email-david.s.gordon@intel.com
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index d3b98c2..1256594 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2268,9 +2268,9 @@ struct drm_i915_gem_request {
 
 };
 
-int i915_gem_request_alloc(struct intel_engine_cs *ring,
-			   struct intel_context *ctx,
-			   struct drm_i915_gem_request **req_out);
+struct drm_i915_gem_request * __must_check
+i915_gem_request_alloc(struct intel_engine_cs *engine,
+		       struct intel_context *ctx);
 void i915_gem_request_cancel(struct drm_i915_gem_request *req);
 void i915_gem_request_free(struct kref *req_ref);
 int i915_gem_request_add_to_client(struct drm_i915_gem_request *req,