phy: tegra: fix device-tree node lookups

commit 046046737bd35bed047460f080ea47e186be731e upstream.

Fix child-node lookups during probe, which ended up searching the whole
device tree depth-first starting at the parents rather than just
matching on their children.

To make things worse, some parent nodes could end up being being
prematurely freed (by tegra_xusb_pad_register()) as
of_find_node_by_name() drops a reference to its first argument.

Fixes: 53d2a715c240 ("phy: Add Tegra XUSB pad controller support")
Cc: Thierry Reding <treding@nvidia.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/phy/tegra/xusb.c b/drivers/phy/tegra/xusb.c
index 4307bf0013e186cd859b779aaaf4c61ddd662a6c..63e916d4d0696156b244fb2c7e0e5f6de606c8e3 100644 (file)
--- a/drivers/phy/tegra/xusb.c
+++ b/drivers/phy/tegra/xusb.c
@@ -75,14 +75,14 @@ MODULE_DEVICE_TABLE(of, tegra_xusb_padctl_of_match);
 static struct device_node *
 tegra_xusb_find_pad_node(struct tegra_xusb_padctl *padctl, const char *name)
 {
-       /*
-        * of_find_node_by_name() drops a reference, so make sure to grab one.
-        */
-       struct device_node *np = of_node_get(padctl->dev->of_node);
+       struct device_node *pads, *np;
+
+       pads = of_get_child_by_name(padctl->dev->of_node, "pads");
+       if (!pads)
+               return NULL;
 
-       np = of_find_node_by_name(np, "pads");
-       if (np)
-               np = of_find_node_by_name(np, name);
+       np = of_get_child_by_name(pads, name);
+       of_node_put(pads);
 
        return np;
 }
@@ -90,16 +90,16 @@ tegra_xusb_find_pad_node(struct tegra_xusb_padctl *padctl, const char *name)
 static struct device_node *
 tegra_xusb_pad_find_phy_node(struct tegra_xusb_pad *pad, unsigned int index)
 {
-       /*
-        * of_find_node_by_name() drops a reference, so make sure to grab one.
-        */
-       struct device_node *np = of_node_get(pad->dev.of_node);
+       struct device_node *np, *lanes;
 
-       np = of_find_node_by_name(np, "lanes");
-       if (!np)
+       lanes = of_get_child_by_name(pad->dev.of_node, "lanes");
+       if (!lanes)
                return NULL;
 
-       return of_find_node_by_name(np, pad->soc->lanes[index].name);
+       np = of_get_child_by_name(lanes, pad->soc->lanes[index].name);
+       of_node_put(lanes);
+
+       return np;
 }
 
 static int
@@ -195,7 +195,7 @@ int tegra_xusb_pad_register(struct tegra_xusb_pad *pad,
        unsigned int i;
        int err;
 
-       children = of_find_node_by_name(pad->dev.of_node, "lanes");
+       children = of_get_child_by_name(pad->dev.of_node, "lanes");
        if (!children)
                return -ENODEV;
 
@@ -444,21 +444,21 @@ static struct device_node *
 tegra_xusb_find_port_node(struct tegra_xusb_padctl *padctl, const char *type,
                          unsigned int index)
 {
-       /*
-        * of_find_node_by_name() drops a reference, so make sure to grab one.
-        */
-       struct device_node *np = of_node_get(padctl->dev->of_node);
+       struct device_node *ports, *np;
+       char *name;
 
-       np = of_find_node_by_name(np, "ports");
-       if (np) {
-               char *name;
+       ports = of_get_child_by_name(padctl->dev->of_node, "ports");
+       if (!ports)
+               return NULL;
 
-               name = kasprintf(GFP_KERNEL, "%s-%u", type, index);
-               if (!name)
-                       return ERR_PTR(-ENOMEM);
-               np = of_find_node_by_name(np, name);
-               kfree(name);
+       name = kasprintf(GFP_KERNEL, "%s-%u", type, index);
+       if (!name) {
+               of_node_put(ports);
+               return ERR_PTR(-ENOMEM);
        }
+       np = of_get_child_by_name(ports, name);
+       kfree(name);
+       of_node_put(ports);
 
        return np;
 }
@@ -847,7 +847,7 @@ static void tegra_xusb_remove_ports(struct tegra_xusb_padctl *padctl)
 
 static int tegra_xusb_padctl_probe(struct platform_device *pdev)
 {
-       struct device_node *np = of_node_get(pdev->dev.of_node);
+       struct device_node *np = pdev->dev.of_node;
        const struct tegra_xusb_padctl_soc *soc;
        struct tegra_xusb_padctl *padctl;
        const struct of_device_id *match;
@@ -855,7 +855,7 @@ static int tegra_xusb_padctl_probe(struct platform_device *pdev)
        int err;
 
        /* for backwards compatibility with old device trees */
-       np = of_find_node_by_name(np, "pads");
+       np = of_get_child_by_name(np, "pads");
        if (!np) {
                dev_warn(&pdev->dev, "deprecated DT, using legacy driver\n");
                return tegra_xusb_padctl_legacy_probe(pdev);