linux-kernel - [PATCH v5 08/11] of/platform: Make sure supplier DT node is device when creating device links

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Message-Id: <20190712235245.202558-9-saravanak@google.com>
Date:   Fri, 12 Jul 2019 16:52:41 -0700
From:   Saravana Kannan <saravanak@...gle.com>
To:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Frank Rowand <frowand.list@...il.com>
Cc:     Saravana Kannan <saravanak@...gle.com>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        David Collins <collinsd@...eaurora.org>,
        kernel-team@...roid.com
Subject: [PATCH v5 08/11] of/platform: Make sure supplier DT node is device
 when creating device links

While most phandle references in common bindings point to the supplier
device node, there are also common bindings where the phandle can
pointing to a child node of the supplier device node.

Therefore, when trying to find the supplier device that corresponds to a
supplier phandle, we need to make sure we are using the supplier's
device node. Otherwise, we'll never find the supplier device.

Signed-off-by: Saravana Kannan <saravanak@...gle.com>
---
 drivers/of/platform.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 98414ba53b1f..cf8625abe30c 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -529,19 +529,33 @@ static int of_link_binding(struct device *dev,
 			   const char *binding, const char *cell)
 {
 	struct of_phandle_args sup_args;
+	struct device_node *sup_np;
 	struct platform_device *sup_dev;
 	unsigned int i = 0, links = 0;
 	u32 dl_flags = DL_FLAG_AUTOPROBE_CONSUMER;
 
 	while (!of_parse_phandle_with_args(dev->of_node, binding, cell, i,
 					   &sup_args)) {
-		if (!of_link_is_valid(dev->of_node, sup_args.np)) {
-			of_node_put(sup_args.np);
+		sup_np = sup_args.np;
+		/*
+		 * Since we are trying to create device links, we need to find
+		 * the actual device node that owns this supplier phandle.
+		 * Often times it's the same node, but sometimes it can be one
+		 * of the parents. So walk up the parent till you find a
+		 * device.
+		 */
+		while (sup_np && !of_find_property(sup_np, "compatible", NULL))
+			sup_np = of_get_next_parent(sup_np);
+		if (!sup_np)
+			continue;
+
+		if (!of_link_is_valid(dev->of_node, sup_np)) {
+			of_node_put(sup_np);
 			continue;
 		}
 		i++;
-		sup_dev = of_find_device_by_node(sup_args.np);
-		of_node_put(sup_args.np);
+		sup_dev = of_find_device_by_node(sup_np);
+		of_node_put(sup_np);
 		if (!sup_dev)
 			continue;
 		if (device_link_add(dev, &sup_dev->dev, dl_flags))
-- 
2.22.0.510.g264f2c817a-goog