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Date:   Thu, 13 Jul 2023 03:42:29 +0100
From:   Daniel Golle <daniel@makrotopia.org>
To:     netdev@vger.kernel.org, linux-mediatek@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Felix Fietkau <nbd@nbd.name>, John Crispin <john@phrozen.org>,
        Sean Wang <sean.wang@mediatek.com>,
        Mark Lee <Mark-MC.Lee@mediatek.com>,
        Lorenzo Bianconi <lorenzo@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Michael Lee <igvtee@gmail.com>
Subject: [PATCH] net: ethernet: mtk_eth_soc: handle probe deferral
Message-ID: <ZK9klTi7XoZZDMeE@makrotopia.org>
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Move the call to of_get_ethdev_address to mtk_add_mac which is part of
the probe function and can hence itself return -EPROBE_DEFER should
of_get_ethdev_address return -EPROBE_DEFER. This allows us to entirely
get rid of the mtk_init function.

The problem of of_get_ethdev_address returning -EPROBE_DEFER surfaced
in situations in which the NVMEM provider holding the MAC address has
not yet be loaded at the time mtk_eth_soc is initially probed. In this
case probing of mtk_eth_soc should be deferred instead of falling back
to use a random MAC address, so once the NVMEM provider becomes
available probing can be repeated.

Fixes: 656e705243fd ("net-next: mediatek: add support for MT7623 ethernet")
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 29 ++++++++-------------
 1 file changed, 11 insertions(+), 18 deletions(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 834c644b67db5..2d15342c260ae 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -3846,23 +3846,6 @@ static int mtk_hw_deinit(struct mtk_eth *eth)
 	return 0;
 }
 
-static int __init mtk_init(struct net_device *dev)
-{
-	struct mtk_mac *mac = netdev_priv(dev);
-	struct mtk_eth *eth = mac->hw;
-	int ret;
-
-	ret = of_get_ethdev_address(mac->of_node, dev);
-	if (ret) {
-		/* If the mac address is invalid, use random mac address */
-		eth_hw_addr_random(dev);
-		dev_err(eth->dev, "generated random MAC address %pM\n",
-			dev->dev_addr);
-	}
-
-	return 0;
-}
-
 static void mtk_uninit(struct net_device *dev)
 {
 	struct mtk_mac *mac = netdev_priv(dev);
@@ -4278,7 +4261,6 @@ static const struct ethtool_ops mtk_ethtool_ops = {
 };
 
 static const struct net_device_ops mtk_netdev_ops = {
-	.ndo_init		= mtk_init,
 	.ndo_uninit		= mtk_uninit,
 	.ndo_open		= mtk_open,
 	.ndo_stop		= mtk_stop,
@@ -4340,6 +4322,17 @@ static int mtk_add_mac(struct mtk_eth *eth, struct device_node *np)
 	mac->hw = eth;
 	mac->of_node = np;
 
+	err = of_get_ethdev_address(mac->of_node, eth->netdev[id]);
+	if (err == -EPROBE_DEFER)
+		return err;
+
+	if (err) {
+		/* If the mac address is invalid, use random mac address */
+		eth_hw_addr_random(eth->netdev[id]);
+		dev_err(eth->dev, "generated random MAC address %pM\n",
+			eth->netdev[id]->dev_addr);
+	}
+
 	memset(mac->hwlro_ip, 0, sizeof(mac->hwlro_ip));
 	mac->hwlro_ip_cnt = 0;
 
-- 
2.41.0