First, the uclass_find_device_by_phandle will try to get phandle of device node by name, calls the dev_read_u32_default, the function always return the argument 'u32 def', as following: ofnode_read_u32_default(ofnode node, const char *propname, u32 def) assert(ofnode_valid(node)); ofnode_read_u32(node, propname, &def); return def;
In this case, the 'def' has been intalized to '-1'.
Second, the phandle of fdt is generated by get_node_phandle in livetree, which is part of dtc script tool, as following: get_node_phandle(struct node *root, struct node *node) static cell_t phandle = 1; if ((node->phandle != 0) && (node->phandle != -1)) return node->phandle; while (get_node_by_phandle(root, phandle)) phandle++;
The cell_t is defined by 'typedef uint32_t cell_t'.
Gernerally, the valid phandle of fdt is from 1 to -2, if dev_read_u32_default return '-1' means the 'u32 def' keeps the intalized value.
Signed-off-by: Jianqun Xu jay.xu@rock-chips.com --- drivers/core/uclass.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/core/uclass.c b/drivers/core/uclass.c index c3f1b73cd6..86cc04ecac 100644 --- a/drivers/core/uclass.c +++ b/drivers/core/uclass.c @@ -385,12 +385,12 @@ int uclass_find_device_by_phandle(enum uclass_id id, struct udevice *parent, { struct udevice *dev; struct uclass *uc; - int find_phandle; + u32 find_phandle; int ret;
*devp = NULL; find_phandle = dev_read_u32_default(parent, name, -1); - if (find_phandle <= 0) + if (find_phandle == -1) return -ENOENT; ret = uclass_get(id, &uc); if (ret)