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Subject[PATCH v3 08/24] drm/sun4i: Add support for traversing graph with TCON TOP
Date
TCON TOP is different from other nodes in graph by having 3 input and 3
output ports. Additionally, connection to TV TCON might lead back to
HDMI mux input port, creating loops.

Add support for traversing such graph.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
---
drivers/gpu/drm/sun4i/sun4i_drv.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)

diff --git a/drivers/gpu/drm/sun4i/sun4i_drv.c b/drivers/gpu/drm/sun4i/sun4i_drv.c
index 20193d6f33ba..e6c62c079146 100644
--- a/drivers/gpu/drm/sun4i/sun4i_drv.c
+++ b/drivers/gpu/drm/sun4i/sun4i_drv.c
@@ -26,6 +26,7 @@
#include "sun4i_frontend.h"
#include "sun4i_framebuffer.h"
#include "sun4i_tcon.h"
+#include "sun8i_tcon_top.h"

DEFINE_DRM_GEM_CMA_FOPS(sun4i_drv_fops);

@@ -197,6 +198,11 @@ static bool sun4i_drv_node_is_tcon(struct device_node *node)
return !!of_match_node(sun4i_tcon_of_table, node);
}

+static bool sun4i_drv_node_is_tcon_top(struct device_node *node)
+{
+ return !!of_match_node(sun8i_tcon_top_of_table, node);
+}
+
static int compare_of(struct device *dev, void *data)
{
DRM_DEBUG_DRIVER("Comparing of node %pOF with %pOF\n",
@@ -258,6 +264,18 @@ static void sun4i_drv_traverse_endpoints(struct endpoint_list *list,
if (sun4i_drv_node_is_tcon(node)) {
struct of_endpoint endpoint;

+ /*
+ * TCON TOP is always probed before TCON. However, TCON
+ * points back to TCON TOP when it is source for HDMI.
+ * We have to skip it here to prevent infinite looping
+ * between TCON TOP and TCON.
+ */
+ if (sun4i_drv_node_is_tcon_top(remote)) {
+ DRM_DEBUG_DRIVER("TCON output endpoint is TCON TOP... skipping\n");
+ of_node_put(remote);
+ continue;
+ }
+
if (of_graph_parse_endpoint(ep, &endpoint)) {
DRM_DEBUG_DRIVER("Couldn't parse endpoint\n");
of_node_put(remote);
@@ -318,6 +336,12 @@ static int sun4i_drv_add_endpoints(struct device *dev,
/* each node has at least one output */
sun4i_drv_traverse_endpoints(list, node, 1);

+ /* TCON TOP has second and third output */
+ if (sun4i_drv_node_is_tcon_top(node)) {
+ sun4i_drv_traverse_endpoints(list, node, 3);
+ sun4i_drv_traverse_endpoints(list, node, 5);
+ }
+
return count;
}

--
2.18.0
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