drm/i915: Report the ring->space from intel_ring_update_space()

Some callers immediately want to know the current ring->space after
calling intel_ring_update_space(), which we can freely provide via the
return parameter.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170504130846.4807-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -52,9 +52,14 @@ static unsigned int __intel_ring_space(unsigned int head,
 	return (head - tail - CACHELINE_BYTES) & (size - 1);
 }
 
-void intel_ring_update_space(struct intel_ring *ring)
+unsigned int intel_ring_update_space(struct intel_ring *ring)
 {
-	ring->space = __intel_ring_space(ring->head, ring->emit, ring->size);
+	unsigned int space;
+
+	space = __intel_ring_space(ring->head, ring->emit, ring->size);
+
+	ring->space = space;
+	return space;
 }
 
 static int
@@ -1659,8 +1664,7 @@ static int wait_for_space(struct drm_i915_gem_request *req, int bytes)
 
 	lockdep_assert_held(&req->i915->drm.struct_mutex);
 
-	intel_ring_update_space(ring);
-	if (ring->space >= bytes)
+	if (intel_ring_update_space(ring) >= bytes)
 		return 0;
 
 	/*

drivers/gpu/drm/i915/intel_ringbuffer.h

@@ -486,7 +486,7 @@ int intel_ring_pin(struct intel_ring *ring,
 		   struct drm_i915_private *i915,
 		   unsigned int offset_bias);
 void intel_ring_reset(struct intel_ring *ring, u32 tail);
-void intel_ring_update_space(struct intel_ring *ring);
+unsigned int intel_ring_update_space(struct intel_ring *ring);
 void intel_ring_unpin(struct intel_ring *ring);
 void intel_ring_free(struct intel_ring *ring);