If 2 similar cells have the same of_compatible (2 instances of the same
functionality), they both are assigned the first found of_node with this
compatible. In the below example, the pdev of both cells get the child@0
of_node.

parent@0 { /* MFD devices with 2 cells
        reg = <0>;
        child@0 {
                reg = <0>;
                compatible = "child-driver";
        };
        child@1 {
                reg = <1>;
                compatible = "child-driver";
        };
};

To avoid this, the found of_nodes are checked to see if they are already
assigned in the children of the parent dev and are only assigned if
still "available" (not assigned to a child).

This allows the 2nd cell's pdev to get the child@1 of_node.

Signed-off-by: Valentin Longchamp <valentin.longch...@keymile.com>
---
 drivers/mfd/mfd-core.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
index 3ac486a..11c5ded 100644
--- a/drivers/mfd/mfd-core.c
+++ b/drivers/mfd/mfd-core.c
@@ -137,6 +137,19 @@ static inline void mfd_acpi_add_device(const struct 
mfd_cell *cell,
 }
 #endif
 
+static inline int is_my_of_node(struct device *dev, void *data)
+{
+       struct device_node *np = data;
+
+       return dev->of_node == np;
+}
+
+static inline int of_node_already_in_children(struct device *dev,
+                                             struct device_node *node)
+{
+       return device_for_each_child(dev, node, is_my_of_node);
+}
+
 static int mfd_add_device(struct device *parent, int id,
                          const struct mfd_cell *cell, atomic_t *usage_count,
                          struct resource *mem_base,
@@ -178,8 +191,10 @@ static int mfd_add_device(struct device *parent, int id,
        if (parent->of_node && cell->of_compatible) {
                for_each_child_of_node(parent->of_node, np) {
                        if (of_device_is_compatible(np, cell->of_compatible)) {
-                               pdev->dev.of_node = np;
-                               break;
+                               if (!of_node_already_in_children(parent, np)) {
+                                       pdev->dev.of_node = np;
+                                       break;
+                               }
                        }
                }
        }
-- 
1.8.3.1

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