[PATCH] net: axienet: allow setups without MDIO

[Daniel Mack]

In setups with fixed-link settings on the hardware bus there is no mdio node
in DTS. axienet_probe() already handles that gracefully but lp->mii_bus is
then NULL.

Fix code that tries to blindly grab the MDIO lock by introducing two helper
functions that make the locking conditional.

Signed-off-by: Daniel Mack <dan...@zonque.org>
---
 drivers/net/ethernet/xilinx/xilinx_axienet.h      | 12 ++++++++++++
 drivers/net/ethernet/xilinx/xilinx_axienet_main.c |  8 ++++----
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet.h 
b/drivers/net/ethernet/xilinx/xilinx_axienet.h
index 1e966a39967e5..aca7f82f6791b 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet.h
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet.h
@@ -504,6 +504,18 @@ static inline u32 axinet_ior_read_mcr(struct axienet_local 
*lp)
        return axienet_ior(lp, XAE_MDIO_MCR_OFFSET);
 }
 
+static inline void axienet_lock_mii(struct axienet_local *lp)
+{
+       if (lp->mii_bus)
+               mutex_lock(&lp->mii_bus->mdio_lock);
+}
+
+static inline void axienet_unlock_mii(struct axienet_local *lp)
+{
+       if (lp->mii_bus)
+               mutex_unlock(&lp->mii_bus->mdio_lock);
+}
+
 /**
  * axienet_iow - Memory mapped Axi Ethernet register write
  * @lp:         Pointer to axienet local structure
diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c 
b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index 3a8775e0ca552..ce33e0a468912 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -1053,9 +1053,9 @@ static int axienet_open(struct net_device *ndev)
         * including the MDIO. MDIO must be disabled before resetting.
         * Hold MDIO bus lock to avoid MDIO accesses during the reset.
         */
-       mutex_lock(&lp->mii_bus->mdio_lock);
+       axienet_lock_mii(lp);
        ret = axienet_device_reset(ndev);
-       mutex_unlock(&lp->mii_bus->mdio_lock);
+       axienet_unlock_mii(lp);
 
        ret = phylink_of_phy_connect(lp->phylink, lp->dev->of_node, 0);
        if (ret) {
@@ -1148,9 +1148,9 @@ static int axienet_stop(struct net_device *ndev)
        }
 
        /* Do a reset to ensure DMA is really stopped */
-       mutex_lock(&lp->mii_bus->mdio_lock);
+       axienet_lock_mii(lp);
        __axienet_device_reset(lp);
-       mutex_unlock(&lp->mii_bus->mdio_lock);
+       axienet_unlock_mii(lp);
 
        cancel_work_sync(&lp->dma_err_task);
 
-- 
2.29.2