drm/omap: dss: Rework output lookup by port node

The omap_dss_find_output_by_port_node() function defined in output.c
looks up an output from its port node. To do so it needs to call helper
functions from dss-of.c to lookup the port parent and the port number.
As omap_dss_find_output_by_port_node() is only called by
omapdss_of_find_source_for_first_ep() from dss-of.c this goes back and
forth between the to source files and isn't very clear.

Simplify the code by passing both the parent and the port number to
omap_dss_find_output_by_port_node() instead of the port node, and rename
the function to omap_dss_find_output_by_port().
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/gpu/drm/omapdrm/dss/dss-of.c

@@ -21,7 +21,8 @@
 
 #include "omapdss.h"
 
-struct device_node *dss_of_port_get_parent_device(struct device_node *port)
+static struct device_node *
+dss_of_port_get_parent_device(struct device_node *port)
 {
 	struct device_node *np;
 	int i;
@@ -45,40 +46,36 @@ struct device_node *dss_of_port_get_parent_device(struct device_node *port)
 	return NULL;
 }
 
-u32 dss_of_port_get_port_number(struct device_node *port)
-{
-	int r;
-	u32 reg;
-
-	r = of_property_read_u32(port, "reg", &reg);
-	if (r)
-		reg = 0;
-
-	return reg;
-}
-
 struct omap_dss_device *
 omapdss_of_find_source_for_first_ep(struct device_node *node)
 {
-	struct device_node *ep;
+	struct device_node *src_node;
 	struct device_node *src_port;
+	struct device_node *ep;
 	struct omap_dss_device *src;
+	u32 port_number = 0;
 
+	/* Get the endpoint... */
 	ep = of_graph_get_endpoint_by_regs(node, 0, 0);
 	if (!ep)
 		return ERR_PTR(-EINVAL);
 
+	/* ... and its remote port... */
 	src_port = of_graph_get_remote_port(ep);
-	if (!src_port) {
 	of_node_put(ep);
+	if (!src_port)
 		return ERR_PTR(-EINVAL);
-	}
-
-	of_node_put(ep);
-
-	src = omap_dss_find_output_by_port_node(src_port);
 
+	/* ... and the remote port's number and parent... */
+	of_property_read_u32(src_port, "reg", &port_number);
+	src_node = dss_of_port_get_parent_device(src_port);
 	of_node_put(src_port);
+	if (!src_node)
+		return NULL;
+
+	/* ... and finally the source. */
+	src = omap_dss_find_output_by_port(src_node, port_number);
+	of_node_put(src_node);
 
 	return src ? src : ERR_PTR(-EPROBE_DEFER);
 }

drivers/gpu/drm/omapdrm/dss/omapdss.h

@@ -576,7 +576,8 @@ int omap_dss_get_num_overlays(void);
 int omapdss_register_output(struct omap_dss_device *output);
 void omapdss_unregister_output(struct omap_dss_device *output);
 struct omap_dss_device *omap_dss_get_output(enum omap_dss_output_id id);
-struct omap_dss_device *omap_dss_find_output_by_port_node(struct device_node *port);
+struct omap_dss_device *omap_dss_find_output_by_port(struct device_node *src,
+						     unsigned int port);
 int omapdss_output_set_device(struct omap_dss_device *out,
 		struct omap_dss_device *dssdev);
 int omapdss_output_unset_device(struct omap_dss_device *out);
@@ -603,9 +604,6 @@ static inline bool omapdss_device_is_enabled(struct omap_dss_device *dssdev)
 struct omap_dss_device *
 omapdss_of_find_source_for_first_ep(struct device_node *node);
 
-struct device_node *dss_of_port_get_parent_device(struct device_node *port);
-u32 dss_of_port_get_port_number(struct device_node *port);
-
 enum dss_writeback_channel {
 	DSS_WB_LCD1_MGR =	0,
 	DSS_WB_LCD2_MGR =	1,

drivers/gpu/drm/omapdrm/dss/output.c

@@ -122,26 +122,15 @@ struct omap_dss_device *omap_dss_get_output(enum omap_dss_output_id id)
 }
 EXPORT_SYMBOL(omap_dss_get_output);
 
-struct omap_dss_device *omap_dss_find_output_by_port_node(struct device_node *port)
+struct omap_dss_device *omap_dss_find_output_by_port(struct device_node *src,
+						     unsigned int port)
 {
-	struct device_node *src_node;
 	struct omap_dss_device *out;
-	u32 reg;
-
-	src_node = dss_of_port_get_parent_device(port);
-	if (!src_node)
-		return NULL;
-
-	reg = dss_of_port_get_port_number(port);
 
 	list_for_each_entry(out, &output_list, output_list) {
-		if (out->dev->of_node == src_node && out->port_num == reg) {
-			of_node_put(src_node);
+		if (out->dev->of_node == src && out->port_num == port)
 			return omap_dss_get_device(out);
 	}
-	}
-
-	of_node_put(src_node);
 
 	return NULL;
 }