drm/i915: Avoid using intel_engine_cs *ring for GPU error capture

Inside the error capture itself, we refer to not only the hardware
engine, its ringbuffer but also the capture state. Finding clear names
for each whilst avoiding mixing ring/intel_engine_cs is tricky. As a
compromise we keep using ering for the error capture.

v2: Use 'ee' locals for struct drm_i915_error_engine

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1469432687-22756-8-git-send-email-chris@chris-wilson.co.uk
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469606850-28659-3-git-send-email-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_drv.h

@@ -512,8 +512,8 @@ struct drm_i915_error_state {
 	struct intel_display_error_state *display;
 	struct drm_i915_error_object *semaphore_obj;
 
-	struct drm_i915_error_ring {
-		bool valid;
+	struct drm_i915_error_engine {
+		int engine_id;
 		/* Software tracked state */
 		bool waiting;
 		int num_waiters;
@@ -578,7 +578,7 @@ struct drm_i915_error_state {
 
 		pid_t pid;
 		char comm[TASK_COMM_LEN];
-	} ring[I915_NUM_ENGINES];
+	} engine[I915_NUM_ENGINES];
 
 	struct drm_i915_error_buffer {
 		u32 size;
@@ -593,7 +593,7 @@ struct drm_i915_error_state {
 		u32 dirty:1;
 		u32 purgeable:1;
 		u32 userptr:1;
-		s32 ring:4;
+		s32 engine:4;
 		u32 cache_level:3;
 	} **active_bo, **pinned_bo;