linux-kernel - [PATCH 4.17 194/220] net: ethernet: fix suspend/resume in davinci

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Message-Id: <20180701160916.289679319@linuxfoundation.org>
Date:   Sun,  1 Jul 2018 18:23:38 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Lukas Wunner <lukas@...ner.de>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.17 194/220] net: ethernet: fix suspend/resume in davinci_emac

4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bartosz Golaszewski <bgolaszewski@...libre.com>

commit dc45519eb181b5687ac8382361a8aa085acd1fe1 upstream.

This patch reverts commit 3243ff2a05ec ("net: ethernet: davinci_emac:
Deduplicate bus_find_device() by name matching") and adds a comment
which should stop anyone from reintroducing the same "fix" in the future.

We can't use bus_find_device_by_name() here because the device name is
not guaranteed to be 'davinci_mdio'. On some systems it can be
'davinci_mdio.0' so we need to use strncmp() against the first part of
the string to correctly match it.

Fixes: 3243ff2a05ec ("net: ethernet: davinci_emac: Deduplicate bus_find_device() by name matching")
Cc: stable@...r.kernel.org
Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
Acked-by: Lukas Wunner <lukas@...ner.de>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/ethernet/ti/davinci_emac.c |   15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/ti/davinci_emac.c
+++ b/drivers/net/ethernet/ti/davinci_emac.c
@@ -1385,6 +1385,11 @@ static int emac_devioctl(struct net_devi
 		return -EOPNOTSUPP;
 }

+static int match_first_device(struct device *dev, void *data)
+{
+	return !strncmp(dev_name(dev), "davinci_mdio", 12);
+}
+
 /**
  * emac_dev_open - EMAC device open
  * @ndev: The DaVinci EMAC network adapter
@@ -1484,8 +1489,14 @@ static int emac_dev_open(struct net_devi

 	/* use the first phy on the bus if pdata did not give us a phy id */
 	if (!phydev && !priv->phy_id) {
-		phy = bus_find_device_by_name(&mdio_bus_type, NULL,
-					      "davinci_mdio");
+		/* NOTE: we can't use bus_find_device_by_name() here because
+		 * the device name is not guaranteed to be 'davinci_mdio'. On
+		 * some systems it can be 'davinci_mdio.0' so we need to use
+		 * strncmp() against the first part of the string to correctly
+		 * match it.
+		 */
+		phy = bus_find_device(&mdio_bus_type, NULL, NULL,
+				      match_first_device);
 		if (phy) {
 			priv->phy_id = dev_name(phy);
 			if (!priv->phy_id || !*priv->phy_id)