[PATCH] mailbox: imx: Fix clk handling in imx_mu_probe()

[Alexey Khoroshilov <khoroshilov@ispras.ru>]

Handling of devm_clk_get() suggests that the driver should support
lack of priv->clk. But imx_mu_probe() fails on clk_prepare_enable(NULL)
in that case.

The patch removes the try to enable absent clk and adds error handling
for mbox_controller_register().

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
---
 drivers/mailbox/imx-mailbox.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/mailbox/imx-mailbox.c b/drivers/mailbox/imx-mailbox.c
index 363d35d5e49d..ddde398f576e 100644
--- a/drivers/mailbox/imx-mailbox.c
+++ b/drivers/mailbox/imx-mailbox.c
@@ -292,10 +292,12 @@ static int imx_mu_probe(struct platform_device *pdev)
 		priv->clk = NULL;
 	}
 
-	ret = clk_prepare_enable(priv->clk);
-	if (ret) {
-		dev_err(dev, "Failed to enable clock\n");
-		return ret;
+	if (priv->clk) {
+		ret = clk_prepare_enable(priv->clk);
+		if (ret) {
+			dev_err(dev, "Failed to enable clock\n");
+			return ret;
+		}
 	}
 
 	for (i = 0; i < IMX_MU_CHANS; i++) {
@@ -324,7 +326,13 @@ static int imx_mu_probe(struct platform_device *pdev)
 
 	imx_mu_init_generic(priv);
 
-	return mbox_controller_register(&priv->mbox);
+	ret = mbox_controller_register(&priv->mbox);
+	if (ret) {
+		clk_disable_unprepare(priv->clk);
+		return ret;
+	}
+
+	return 0;
 }
 
 static int imx_mu_remove(struct platform_device *pdev)
-- 
2.7.4