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

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

From: Florian Fainelli <f.faine...@gmail.com>


[ Upstream commit 5701659004d68085182d2fd4199c79172165fa65 ]

There is currently a small window during which the network device registered by
stmmac can be made visible, yet all resources, including and clock and MDIO bus
have not had a chance to be set up, this can lead to the following error to
occur:

[  473.919358] stmmaceth 0000:01:00.0 (unnamed net_device) (uninitialized):
                stmmac_dvr_probe: warning: cannot get CSR clock
[  473.919382] stmmaceth 0000:01:00.0: no reset control found
[  473.919412] stmmac - user ID: 0x10, Synopsys ID: 0x42
[  473.919429] stmmaceth 0000:01:00.0: DMA HW capability register supported
[  473.919436] stmmaceth 0000:01:00.0: RX Checksum Offload Engine supported
[  473.919443] stmmaceth 0000:01:00.0: TX Checksum insertion supported
[  473.919451] stmmaceth 0000:01:00.0 (unnamed net_device) (uninitialized):
                Enable RX Mitigation via HW Watchdog Timer
[  473.921395] libphy: PHY stmmac-1:00 not found
[  473.921417] stmmaceth 0000:01:00.0 eth0: Could not attach to PHY
[  473.921427] stmmaceth 0000:01:00.0 eth0: stmmac_open: Cannot attach to
                PHY (error: -19)
[  473.959710] libphy: stmmac: probed
[  473.959724] stmmaceth 0000:01:00.0 eth0: PHY ID 01410cc2 at 0 IRQ POLL
                (stmmac-1:00) active
[  473.959728] stmmaceth 0000:01:00.0 eth0: PHY ID 01410cc2 at 1 IRQ POLL
                (stmmac-1:01)
[  473.959731] stmmaceth 0000:01:00.0 eth0: PHY ID 01410cc2 at 2 IRQ POLL
                (stmmac-1:02)
[  473.959734] stmmaceth 0000:01:00.0 eth0: PHY ID 01410cc2 at 3 IRQ POLL
                (stmmac-1:03)

Fix this by making sure that register_netdev() is the last thing being done,
which guarantees that the clock and the MDIO bus are available.

Fixes: 4bfcbd7abce2 ("stmmac: Move the mdio_register/_unregister in 
probe/remove")
Reported-by: Kweh, Hock Leong <hock.leong.k...@intel.com>
Signed-off-by: Florian Fainelli <f.faine...@gmail.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c |   23 ++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3349,12 +3349,6 @@ int stmmac_dvr_probe(struct device *devi
        spin_lock_init(&priv->lock);
        spin_lock_init(&priv->tx_lock);
 
-       ret = register_netdev(ndev);
-       if (ret) {
-               pr_err("%s: ERROR %i registering the device\n", __func__, ret);
-               goto error_netdev_register;
-       }
-
        /* If a specific clk_csr value is passed from the platform
         * this means that the CSR Clock Range selection cannot be
         * changed at run-time and it is fixed. Viceversa the driver'll try to
@@ -3376,15 +3370,24 @@ int stmmac_dvr_probe(struct device *devi
                if (ret < 0) {
                        pr_debug("%s: MDIO bus (id: %d) registration failed",
                                 __func__, priv->plat->bus_id);
-                       goto error_mdio_register;
+                       goto error_napi_register;
                }
        }
 
-       return 0;
+       ret = register_netdev(ndev);
+       if (ret) {
+               pr_err("%s: ERROR %i registering the device\n", __func__, ret);
+               goto error_netdev_register;
+       }
+
+       return ret;
 
-error_mdio_register:
-       unregister_netdev(ndev);
 error_netdev_register:
+       if (priv->hw->pcs != STMMAC_PCS_RGMII &&
+           priv->hw->pcs != STMMAC_PCS_TBI &&
+           priv->hw->pcs != STMMAC_PCS_RTBI)
+               stmmac_mdio_unregister(ndev);
+error_napi_register:
        netif_napi_del(&priv->napi);
 error_hw_init:
        clk_disable_unprepare(priv->pclk);


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