drm/i915: Remove the now redundant 'obj->ring'

The ring member of the object structure was always updated with the
last_read_seqno member. Thus with the conversion to last_read_req, obj->ring is
now a direct copy of obj->last_read_req->ring. This makes it somewhat redundant
and potentially misleading (especially as there was no comment to explain its
purpose).

This checkin removes the redundant field. Many uses were simply testing for
non-null to see if the object is active on the GPU. Some of these have been
converted to check 'obj->active' instead. Others (where the last_read_req is
about to be used anyway) have been changed to check obj->last_read_req. The rest
simply pull the ring out from the request structure and proceed as before.

For: VIZ-4377
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Thomas Daniel <Thomas.Daniel@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -166,8 +166,9 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
 		*t = '\0';
 		seq_printf(m, " (%s mappable)", s);
 	}
-	if (obj->ring != NULL)
-		seq_printf(m, " (%s)", obj->ring->name);
+	if (obj->last_read_req != NULL)
+		seq_printf(m, " (%s)",
+			   i915_gem_request_get_ring(obj->last_read_req)->name);
 	if (obj->frontbuffer_bits)
 		seq_printf(m, " (frontbuffer: 0x%03x)", obj->frontbuffer_bits);
 }
@@ -334,7 +335,7 @@ static int per_file_stats(int id, void *ptr, void *data)
 			if (ppgtt->file_priv != stats->file_priv)
 				continue;
 
-			if (obj->ring) /* XXX per-vma statistic */
+			if (obj->active) /* XXX per-vma statistic */
 				stats->active += obj->base.size;
 			else
 				stats->inactive += obj->base.size;
@@ -344,7 +345,7 @@ static int per_file_stats(int id, void *ptr, void *data)
 	} else {
 		if (i915_gem_obj_ggtt_bound(obj)) {
 			stats->global += obj->base.size;
-			if (obj->ring)
+			if (obj->active)
 				stats->active += obj->base.size;
 			else
 				stats->inactive += obj->base.size;

drivers/gpu/drm/i915/i915_drv.h

@@ -1941,8 +1941,6 @@ struct drm_i915_gem_object {
 	void *dma_buf_vmapping;
 	int vmapping_count;
 
-	struct intel_engine_cs *ring;
-
 	/** Breadcrumb of last rendering to the buffer. */
 	struct drm_i915_gem_request *last_read_req;
 	struct drm_i915_gem_request *last_write_req;

drivers/gpu/drm/i915/i915_gem.c

@@ -2263,14 +2263,18 @@ static void
 i915_gem_object_move_to_active(struct drm_i915_gem_object *obj,
 			       struct intel_engine_cs *ring)
 {
-	struct drm_i915_gem_request *req = intel_ring_get_request(ring);
+	struct drm_i915_gem_request *req;
+	struct intel_engine_cs *old_ring;
 
 	BUG_ON(ring == NULL);
-	if (obj->ring != ring && obj->last_write_req) {
+
+	req = intel_ring_get_request(ring);
+	old_ring = i915_gem_request_get_ring(obj->last_read_req);
+
+	if (old_ring != ring && obj->last_write_req) {
 		/* Keep the request relative to the current ring */
 		i915_gem_request_assign(&obj->last_write_req, req);
 	}
-	obj->ring = ring;
 
 	/* Add a reference if we're newly entering the active list. */
 	if (!obj->active) {
@@ -2309,7 +2313,6 @@ i915_gem_object_move_to_inactive(struct drm_i915_gem_object *obj)
 	intel_fb_obj_flush(obj, true);
 
 	list_del_init(&obj->ring_list);
-	obj->ring = NULL;
 
 	i915_gem_request_assign(&obj->last_read_req, NULL);
 	i915_gem_request_assign(&obj->last_write_req, NULL);
@@ -2326,9 +2329,7 @@ i915_gem_object_move_to_inactive(struct drm_i915_gem_object *obj)
 static void
 i915_gem_object_retire(struct drm_i915_gem_object *obj)
 {
-	struct intel_engine_cs *ring = obj->ring;
-
-	if (ring == NULL)
+	if (obj->last_read_req == NULL)
 		return;
 
 	if (i915_gem_request_completed(obj->last_read_req, true))
@@ -2861,14 +2862,17 @@ i915_gem_idle_work_handler(struct work_struct *work)
 static int
 i915_gem_object_flush_active(struct drm_i915_gem_object *obj)
 {
+	struct intel_engine_cs *ring;
 	int ret;
 
 	if (obj->active) {
+		ring = i915_gem_request_get_ring(obj->last_read_req);
+
 		ret = i915_gem_check_olr(obj->last_read_req);
 		if (ret)
 			return ret;
 
-		i915_gem_retire_requests_ring(obj->ring);
+		i915_gem_retire_requests_ring(ring);
 	}
 
 	return 0;
@@ -2971,10 +2975,12 @@ int
 i915_gem_object_sync(struct drm_i915_gem_object *obj,
 		     struct intel_engine_cs *to)
 {
-	struct intel_engine_cs *from = obj->ring;
+	struct intel_engine_cs *from;
 	u32 seqno;
 	int ret, idx;
 
+	from = i915_gem_request_get_ring(obj->last_read_req);
+
 	if (from == NULL || to == from)
 		return 0;
 
@@ -3929,7 +3935,7 @@ i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
 	bool was_pin_display;
 	int ret;
 
-	if (pipelined != obj->ring) {
+	if (pipelined != i915_gem_request_get_ring(obj->last_read_req)) {
 		ret = i915_gem_object_sync(obj, pipelined);
 		if (ret)
 			return ret;
@@ -4284,9 +4290,11 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
 	ret = i915_gem_object_flush_active(obj);
 
 	args->busy = obj->active;
-	if (obj->ring) {
+	if (obj->last_read_req) {
+		struct intel_engine_cs *ring;
 		BUILD_BUG_ON(I915_NUM_RINGS > 16);
-		args->busy |= intel_ring_flag(obj->ring) << 16;
+		ring = i915_gem_request_get_ring(obj->last_read_req);
+		args->busy |= intel_ring_flag(ring) << 16;
 	}
 
 	drm_gem_object_unreference(&obj->base);

drivers/gpu/drm/i915/i915_gem_context.c

@@ -619,7 +619,8 @@ static int do_switch(struct intel_engine_cs *ring,
 		 * swapped, but there is no way to do that yet.
 		 */
 		from->legacy_hw_ctx.rcs_state->dirty = 1;
-		BUG_ON(from->legacy_hw_ctx.rcs_state->ring != ring);
+		BUG_ON(i915_gem_request_get_ring(
+			from->legacy_hw_ctx.rcs_state->last_read_req) != ring);
 
 		/* obj is kept alive until the next request by its active ref */
 		i915_gem_object_ggtt_unpin(from->legacy_hw_ctx.rcs_state);

drivers/gpu/drm/i915/i915_gpu_error.c

@@ -683,7 +683,8 @@ static void capture_bo(struct drm_i915_error_buffer *err,
 	err->dirty = obj->dirty;
 	err->purgeable = obj->madv != I915_MADV_WILLNEED;
 	err->userptr = obj->userptr.mm != NULL;
-	err->ring = obj->ring ? obj->ring->id : -1;
+	err->ring = obj->last_read_req ?
+			i915_gem_request_get_ring(obj->last_read_req)->id : -1;
 	err->cache_level = obj->cache_level;
 }
 

drivers/gpu/drm/i915/intel_display.c

@@ -9528,7 +9528,7 @@ static bool use_mmio_flip(struct intel_engine_cs *ring,
 	else if (i915.enable_execlists)
 		return true;
 	else
-		return ring != obj->ring;
+		return ring != i915_gem_request_get_ring(obj->last_read_req);
 }
 
 static void skl_do_mmio_flip(struct intel_crtc *intel_crtc)
@@ -9888,7 +9888,7 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
 	} else if (IS_IVYBRIDGE(dev)) {
 		ring = &dev_priv->ring[BCS];
 	} else if (INTEL_INFO(dev)->gen >= 7) {
-		ring = obj->ring;
+		ring = i915_gem_request_get_ring(obj->last_read_req);
 		if (ring == NULL || ring->id != RCS)
 			ring = &dev_priv->ring[BCS];
 	} else {
@@ -9910,7 +9910,8 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
 
 		i915_gem_request_assign(&work->flip_queued_req,
 					obj->last_write_req);
-		work->flip_queued_ring = obj->ring;
+		work->flip_queued_ring =
+				i915_gem_request_get_ring(obj->last_write_req);
 	} else {
 		ret = dev_priv->display.queue_flip(dev, crtc, fb, obj, ring,
 						   page_flip_flags);