linux-kernel - [PATCH v1 4/5] of: property: Make sure child dependencies don't block probing of parent

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Message-Id: <20191028220027.251605-5-saravanak@google.com>
Date:   Mon, 28 Oct 2019 15:00:25 -0700
From:   Saravana Kannan <saravanak@...gle.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Len Brown <lenb@...nel.org>
Cc:     Saravana Kannan <saravanak@...gle.com>, kernel-team@...roid.com,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-acpi@...r.kernel.org
Subject: [PATCH v1 4/5] of: property: Make sure child dependencies don't block
 probing of parent

When creating device links to proxy the sync_state() needs of child
dependencies, create SYNC_STATE_ONLY device links so that children
dependencies don't block probing of the parent.

Also, differentiate between missing suppliers of parent device vs
missing suppliers of child devices so that driver core doesn't block
parent device probing when only child supplier dependencies are missing.

Signed-off-by: Saravana Kannan <saravanak@...gle.com>
---
 drivers/of/property.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/of/property.c b/drivers/of/property.c
index 2808832b2e86..f16f85597ccc 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -1032,10 +1032,10 @@ static bool of_is_ancestor_of(struct device_node *test_ancestor,
  * - -EINVAL if the supplier link is invalid and should not be created
  * - -ENODEV if there is no device that corresponds to the supplier phandle
  */
-static int of_link_to_phandle(struct device *dev, struct device_node *sup_np)
+static int of_link_to_phandle(struct device *dev, struct device_node *sup_np,
+			      u32 dl_flags)
 {
 	struct device *sup_dev;
-	u32 dl_flags = DL_FLAG_AUTOPROBE_CONSUMER;
 	int ret = 0;
 	struct device_node *tmp_np = sup_np;
 
@@ -1195,13 +1195,20 @@ static int of_link_property(struct device *dev, struct device_node *con_np,
 	unsigned int i = 0;
 	bool matched = false;
 	int ret = 0;
+	u32 dl_flags;
+
+	if (dev->of_node == con_np)
+		dl_flags = DL_FLAG_AUTOPROBE_CONSUMER;
+	else
+		dl_flags = DL_FLAG_SYNC_STATE_ONLY;
 
 	/* Do not stop at first failed link, link all available suppliers. */
 	while (!matched && s->parse_prop) {
 		while ((phandle = s->parse_prop(con_np, prop_name, i))) {
 			matched = true;
 			i++;
-			if (of_link_to_phandle(dev, phandle) == -EAGAIN)
+			if (of_link_to_phandle(dev, phandle, dl_flags)
+								== -EAGAIN)
 				ret = -EAGAIN;
 			of_node_put(phandle);
 		}
@@ -1219,10 +1226,10 @@ static int of_link_to_suppliers(struct device *dev,
 
 	for_each_property_of_node(con_np, p)
 		if (of_link_property(dev, con_np, p->name))
-			ret = -EAGAIN;
+			ret = -ENODEV;
 
 	for_each_child_of_node(con_np, child)
-		if (of_link_to_suppliers(dev, child))
+		if (of_link_to_suppliers(dev, child) && !ret)
 			ret = -EAGAIN;
 
 	return ret;
-- 
2.24.0.rc0.303.g954a862665-goog