drm/i915: Rename intel_timeline.sync_seqno[] to .global_sync[]

With the addition of the inter-context intel_time.sync map, having a
very similar sync_seqno[] is confusing. Aide the reader by denoting that
this is a pre-allocated array for storing semaphore sync points wrt to
the global seqno.

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/20170503093924.5320-5-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_gem_request.c

@@ -218,8 +218,8 @@ static int reset_all_global_seqno(struct drm_i915_private *i915, u32 seqno)
 		tl->seqno = seqno;
 
 		list_for_each_entry(timeline, &i915->gt.timelines, link)
-			memset(timeline->engine[id].sync_seqno, 0,
-			       sizeof(timeline->engine[id].sync_seqno));
+			memset(timeline->engine[id].global_sync, 0,
+			       sizeof(timeline->engine[id].global_sync));
 	}
 
 	return 0;
@@ -715,7 +715,7 @@ i915_gem_request_await_request(struct drm_i915_gem_request *to,
 		return ret < 0 ? ret : 0;
 	}
 
-	if (seqno <= to->timeline->sync_seqno[from->engine->id])
+	if (seqno <= to->timeline->global_sync[from->engine->id])
 		return 0;
 
 	trace_i915_gem_ring_sync_to(to, from);
@@ -733,7 +733,7 @@ i915_gem_request_await_request(struct drm_i915_gem_request *to,
 			return ret;
 	}
 
-	to->timeline->sync_seqno[from->engine->id] = seqno;
+	to->timeline->global_sync[from->engine->id] = seqno;
 	return 0;
 }
 

drivers/gpu/drm/i915/i915_gem_timeline.h

@@ -68,7 +68,14 @@ struct intel_timeline {
 	 * redundant and we can discard it without loss of generality.
 	 */
 	struct i915_syncmap *sync;
-	u32 sync_seqno[I915_NUM_ENGINES];
+	/**
+	 * Separately to the inter-context seqno map above, we track the last
+	 * barrier (e.g. semaphore wait) to the global engine timelines. Note
+	 * that this tracks global_seqno rather than the context.seqno, and
+	 * so it is subject to the limitations of hw wraparound and that we
+	 * may need to revoke global_seqno (on pre-emption).
+	 */
+	u32 global_sync[I915_NUM_ENGINES];
 
 	struct i915_gem_timeline *common;
 };