netdev - [PATCH net-next 2/3] dpaa2-mac: return -EPROBE_DEFER from dpaa2_mac

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Date:   Thu,  6 Jan 2022 15:59:04 +0200
From:   Ioana Ciornei <ioana.ciornei@....com>
To:     davem@...emloft.net, kuba@...nel.org
Cc:     netdev@...r.kernel.org, robert-ionut.alexa@....com,
        Ioana Ciornei <ioana.ciornei@....com>
Subject: [PATCH net-next 2/3] dpaa2-mac: return -EPROBE_DEFER from dpaa2_mac_open in case the fwnode is not set

We could get into a situation when the fwnode of the parent device is
not yet set because its probe didn't yet finish. When this happens, any
caller of the dpaa2_mac_open() will not have the fwnode available, thus
cause problems at the PHY connect time.

Avoid this by just returning -EPROBE_DEFER from the dpaa2_mac_open when
this happens.

Signed-off-by: Ioana Ciornei <ioana.ciornei@....com>
---
 drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c
index e80376c6e55e..623d113b6581 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c
@@ -54,6 +54,12 @@ static struct fwnode_handle *dpaa2_mac_get_node(struct device *dev,
 		parent = of_fwnode_handle(dpmacs);
 	} else if (is_acpi_node(fwnode)) {
 		parent = fwnode;
+	} else {
+		/* The root dprc device didn't yet get to finalize it's probe,
+		 * thus the fwnode field is not yet set. Defer probe if we are
+		 * facing this situation.
+		 */
+		return ERR_PTR(-EPROBE_DEFER);
 	}
 
 	if (!parent)
@@ -330,6 +336,7 @@ int dpaa2_mac_open(struct dpaa2_mac *mac)
 {
 	struct fsl_mc_device *dpmac_dev = mac->mc_dev;
 	struct net_device *net_dev = mac->net_dev;
+	struct fwnode_handle *fw_node;
 	int err;
 
 	err = dpmac_open(mac->mc_io, 0, dpmac_dev->obj_desc.id,
@@ -349,7 +356,13 @@ int dpaa2_mac_open(struct dpaa2_mac *mac)
 	/* Find the device node representing the MAC device and link the device
 	 * behind the associated netdev to it.
 	 */
-	mac->fw_node = dpaa2_mac_get_node(&mac->mc_dev->dev, mac->attr.id);
+	fw_node = dpaa2_mac_get_node(&mac->mc_dev->dev, mac->attr.id);
+	if (IS_ERR(fw_node)) {
+		err = PTR_ERR(fw_node);
+		goto err_close_dpmac;
+	}
+
+	mac->fw_node = fw_node;
 	net_dev->dev.of_node = to_of_node(mac->fw_node);
 
 	return 0;
-- 
2.33.1