[PATCH] soc: apple: sart: require device link for consumers

[Pengpeng Hou]

devm_apple_sart_get() obtains the supplier platform device and attempts
to create a runtime-PM device link to it, but it ignores device_link_add()
failure.  A consumer can then continue without the dependency that keeps
the SART supplier ordered and runtime-PM reachable.

Treat a failed device link as an error and drop the supplier device
reference before returning.

Signed-off-by: Pengpeng Hou <pengpeng@xxxxxxxxxxx>
---
 drivers/soc/apple/sart.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/apple/sart.c b/drivers/soc/apple/sart.c
index 9eaf3febb382..66b99955b395 100644
--- a/drivers/soc/apple/sart.c
+++ b/drivers/soc/apple/sart.c
@@ -218,6 +218,7 @@ struct apple_sart *devm_apple_sart_get(struct device *dev)
 {
 	struct device_node *sart_node;
 	struct platform_device *sart_pdev;
+	struct device_link *link;
 	struct apple_sart *sart;
 
 	sart_node = of_parse_phandle(dev->of_node, "apple,sart", 0);
@@ -236,8 +237,12 @@ struct apple_sart *devm_apple_sart_get(struct device *dev)
 		return ERR_PTR(-EPROBE_DEFER);
 	}
 
-	device_link_add(dev, &sart_pdev->dev,
-			DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_SUPPLIER);
+	link = device_link_add(dev, &sart_pdev->dev,
+			       DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_SUPPLIER);
+	if (!link) {
+		put_device(&sart_pdev->dev);
+		return ERR_PTR(-ENODEV);
+	}
 
 	put_device(&sart_pdev->dev);
 
-- 
2.50.1 (Apple Git-155)