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From: Chen-Yu Tsai <wens@csie.org>
Date: Sat, 14 Oct 2017 12:02:46 +0800
Subject: drm/sun4i: don't add components that are already in the queue
Git-commit: e8afb7b67fbadfbb2b4fd74bf34566e64cbcbe6f
Patch-mainline: v4.15-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

Even though the components framework can handle duplicate entries,
the extra entries cause a lot more debug messages to be generated,
which would be confusing to developers not familiar with our driver
and the framework in general.

Instead, we can scan the relatively small queue and check if the
component to be added is already queued up. Since the display
pipelines are symmetrical (not considering the third display
pipeline on the A80), and we add components level by level, when
we get to the second instance at the same level, any shared downstream
components would already be in the queue.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171014040252.9621-2-wens@csie.org

Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/sun4i/sun4i_drv.c |   16 ++++++++++++++++
 1 file changed, 16 insertions(+)

--- a/drivers/gpu/drm/sun4i/sun4i_drv.c
+++ b/drivers/gpu/drm/sun4i/sun4i_drv.c
@@ -226,6 +226,18 @@ struct endpoint_list {
 	struct list_head list;
 };
 
+static bool node_is_in_list(struct list_head *endpoints,
+			    struct device_node *node)
+{
+	struct endpoint_list *endpoint;
+
+	list_for_each_entry(endpoint, endpoints, list)
+		if (endpoint->node == node)
+			return true;
+
+	return false;
+}
+
 static int sun4i_drv_add_endpoints(struct device *dev,
 				   struct list_head *endpoints,
 				   struct component_match **match,
@@ -292,6 +304,10 @@ static int sun4i_drv_add_endpoints(struc
 			}
 		}
 
+		/* skip downstream node if it is already in the queue */
+		if (node_is_in_list(endpoints, remote))
+			continue;
+
 		/* Add downstream nodes to the queue */
 		endpoint = kzalloc(sizeof(*endpoint), GFP_KERNEL);
 		if (!endpoint) {