drm/omap: Prepare DSS for probing without legacy platform data

In order to probe display subsystem (DSS) components with ti-sysc
interconnect target module without legacy platform data and using
devicetree, we need to update dss probing a bit.

In the device tree, we will be defining the data also for the interconnect
target modules as DSS really is a private interconnect. There is some
information about that in 4460 TRM in "Figure 10-3. DSS Integration" for
example where it mentions "32-bit interconnect (SLX)".

The changes we need to make are:

1. Parse also device tree subnodes for the compatible property fixup

2. Update the component code to consider device tree subnodes

Cc: dri-devel@lists.freedesktop.org
Cc: Jyri Sarha <jsarha@ti.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

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

@@ -1339,9 +1339,15 @@ static int dss_component_compare(struct device *dev, void *data)
 	return dev == child;
 }
 
+struct dss_component_match_data {
+	struct device *dev;
+	struct component_match **match;
+};
+
 static int dss_add_child_component(struct device *dev, void *data)
 {
-	struct component_match **match = data;
+	struct dss_component_match_data *cmatch = data;
+	struct component_match **match = cmatch->match;
 
 	/*
 	 * HACK
@@ -1352,7 +1358,17 @@ static int dss_add_child_component(struct device *dev, void *data)
 	if (strstr(dev_name(dev), "rfbi"))
 		return 0;
 
-	component_match_add(dev->parent, match, dss_component_compare, dev);
+	/*
+	 * Handle possible interconnect target modules defined within the DSS.
+	 * The DSS components can be children of an interconnect target module
+	 * after the device tree has been updated for the module data.
+	 * See also omapdss_boot_init() for compatible fixup.
+	 */
+	if (strstr(dev_name(dev), "target-module"))
+		return device_for_each_child(dev, cmatch,
+					     dss_add_child_component);
+
+	component_match_add(cmatch->dev, match, dss_component_compare, dev);
 
 	return 0;
 }
@@ -1395,6 +1411,7 @@ static int dss_probe_hardware(struct dss_device *dss)
 static int dss_probe(struct platform_device *pdev)
 {
 	const struct soc_device_attribute *soc;
+	struct dss_component_match_data cmatch;
 	struct component_match *match = NULL;
 	struct resource *dss_mem;
 	struct dss_device *dss;
@@ -1472,7 +1489,9 @@ static int dss_probe(struct platform_device *pdev)
 
 	omapdss_gather_components(&pdev->dev);
 
-	device_for_each_child(&pdev->dev, &match, dss_add_child_component);
+	cmatch.dev = &pdev->dev;
+	cmatch.match = &match;
+	device_for_each_child(&pdev->dev, &cmatch, dss_add_child_component);
 
 	r = component_master_add_with_match(&pdev->dev, &dss_component_ops, match);
 	if (r)

drivers/gpu/drm/omapdrm/dss/omapdss-boot-init.c

@@ -183,9 +183,24 @@ static const struct of_device_id omapdss_of_fixups_whitelist[] __initconst = {
 	{},
 };
 
+static void __init omapdss_find_children(struct device_node *np)
+{
+	struct device_node *child;
+
+	for_each_available_child_of_node(np, child) {
+		if (!of_find_property(child, "compatible", NULL))
+			continue;
+
+		omapdss_walk_device(child, true);
+
+		if (of_device_is_compatible(child, "ti,sysc"))
+			omapdss_find_children(child);
+	}
+}
+
 static int __init omapdss_boot_init(void)
 {
-	struct device_node *dss, *child;
+	struct device_node *dss;
 
 	INIT_LIST_HEAD(&dss_conv_list);
 
@@ -195,13 +210,7 @@ static int __init omapdss_boot_init(void)
 		return 0;
 
 	omapdss_walk_device(dss, true);
-
-	for_each_available_child_of_node(dss, child) {
-		if (!of_find_property(child, "compatible", NULL))
-			continue;
-
-		omapdss_walk_device(child, true);
-	}
+	omapdss_find_children(dss);
 
 	while (!list_empty(&dss_conv_list)) {
 		struct dss_conv_node *n;