drm/i915: Remove intel_ring_get_tail()

Joonas doesn't like the tiny function, especially if I go around making
it more complicated and using it elsewhere. To remove that temptation,
remove the function!

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1469432687-22756-21-git-send-email-chris@chris-wilson.co.uk
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470174640-18242-11-git-send-email-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_gem_request.c

@@ -419,7 +419,7 @@ void __i915_add_request(struct drm_i915_gem_request *request,
 	 * should already have been reserved in the ring buffer. Let the ring
 	 * know that it is time to use that space up.
 	 */
-	request_start = intel_ring_get_tail(ring);
+	request_start = ring->tail;
 	reserved_tail = request->reserved_space;
 	request->reserved_space = 0;
 
@@ -464,19 +464,19 @@ void __i915_add_request(struct drm_i915_gem_request *request,
 	 * GPU processing the request, we never over-estimate the
 	 * position of the head.
 	 */
-	request->postfix = intel_ring_get_tail(ring);
+	request->postfix = ring->tail;
 
 	if (i915.enable_execlists) {
 		ret = engine->emit_request(request);
 	} else {
 		ret = engine->add_request(request);
 
-		request->tail = intel_ring_get_tail(ring);
+		request->tail = ring->tail;
 	}
 	/* Not allowed to fail! */
 	WARN(ret, "emit|add_request failed: %d!\n", ret);
 	/* Sanity check that the reserved size was large enough. */
-	ret = intel_ring_get_tail(ring) - request_start;
+	ret = ring->tail - request_start;
 	if (ret < 0)
 		ret += ring->size;
 	WARN_ONCE(ret > reserved_tail,

drivers/gpu/drm/i915/intel_ringbuffer.h

@@ -490,11 +490,6 @@ static inline u32 intel_engine_get_seqno(struct intel_engine_cs *engine)
 
 int init_workarounds_ring(struct intel_engine_cs *engine);
 
-static inline u32 intel_ring_get_tail(struct intel_ring *ring)
-{
-	return ring->tail;
-}
-
 /*
  * Arbitrary size for largest possible 'add request' sequence. The code paths
  * are complex and variable. Empirical measurement shows that the worst case