Re: [PATCH net-next 1/4] drivers: net: xgene-v2: Add MDIO support

On Tue, Mar 21, 2017 at 1:35 PM, Andrew Lunn [off-list ref] wrote:

quoted

@@ -511,9 +512,9 @@ static int xge_close(struct net_device *ndev)
 {
      struct xge_pdata *pdata = netdev_priv(ndev);

-     netif_carrier_off(ndev);
      netif_stop_queue(ndev);
      xge_mac_disable(pdata);
+     phy_stop(ndev->phydev);

      xge_intr_disable(pdata);
      xge_free_irq(ndev);

@@ -683,9 +684,14 @@ static int xge_probe(struct platform_device *pdev)
      if (ret)
              goto err;

+     spin_lock_init(&pdata->mdio_lock);
+

...

quoted

+static int xge_mdio_write(struct mii_bus *bus, int phy_id, int reg, u16 data)
+{
+     struct xge_pdata *pdata = bus->priv;
+     u32 done, val = 0;
+     u8 wait = 10;
+     int ret = 0;
+
+     spin_lock(&pdata->mdio_lock);
+
+     SET_REG_BITS(&val, PHY_ADDR, phy_id);
+     SET_REG_BITS(&val, REG_ADDR, reg);
+     xge_wr_csr(pdata, MII_MGMT_ADDRESS, val);
+
+     xge_wr_csr(pdata, MII_MGMT_CONTROL, data);
+     do {
+             usleep_range(5, 10);
+             done = xge_rd_csr(pdata, MII_MGMT_INDICATORS);
+     } while ((done & MII_MGMT_BUSY) && wait--);
+
+     if (done & MII_MGMT_BUSY) {
+             dev_err(&bus->dev, "MII_MGMT write failed\n");
+             ret = -ETIMEDOUT;
+     }
+
+     spin_unlock(&pdata->mdio_lock);
+
+     return ret;
+}
+
+static int xge_mdio_read(struct mii_bus *bus, int phy_id, int reg)
+{
+     struct xge_pdata *pdata = bus->priv;
+     u32 data, done, val = 0;
+     u8 wait = 10;
+
+     spin_lock(&pdata->mdio_lock);
+

Hi Iyappan

Please could you explain what this lock is protecting which the
mii_bus mdio_lock in mdio_bus.c is not protecting?

Hi Keyur,

Please could you explain what this lock is protecting which the
mii_bus mdio_lock in mdio_bus.c is not protecting?

I agree with him.  Actually there is a mutex on mdio_bus.  So the mdio
bus read and write are locked.  we don't need the lock.

Do you agree ?

Thanks
        Andrew