drm/i915: Virtualize the ringbuffer signal func

This abstraction again is in preparation for gen8. Gen8 will bring new
semantics for doing this operation.

While here, make the writes of MI_NOOPs explicit for non-existent rings.
This should have been implicit before.

NOTE: This is going to be removed in a few patches.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 7 insertions, 4 deletions

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 6a44a64b4d70..830ff26aaddc 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -120,16 +120,19 @@ struct  intel_ring_buffer {
 
         struct {
                 u32     sync_seqno[I915_NUM_RINGS-1];
-                /* AKA wait() */
-                int     (*sync_to)(struct intel_ring_buffer *ring,
-                                   struct intel_ring_buffer *to,
-                                   u32 seqno);
+
                 struct {
                         /* our mbox written by others */
                         u32             wait[I915_NUM_RINGS];
                         /* mboxes this ring signals to */
                         u32             signal[I915_NUM_RINGS];
                 } mbox;
+
+                /* AKA wait() */
+                int     (*sync_to)(struct intel_ring_buffer *ring,
+                                   struct intel_ring_buffer *to,
+                                   u32 seqno);
+                void    (*signal)(struct intel_ring_buffer *signaller);
         } semaphore;
 
         /**