sfc: Serialise tenxpress_special_reset() with statistics fetches

On some boards 10Xpress feeds a 156 MHz clock to the Falcon XMAC.  MAC
statistics DMA can fail while this clock is stopped during a PHY reset.

From: Steve Hodgson <shodgson@solarflare.com>
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

diff --git a/drivers/net/sfc/tenxpress.c b/drivers/net/sfc/tenxpress.c
index 77e7f3a..2ad3d8d 100644 (file)
--- a/drivers/net/sfc/tenxpress.c
+++ b/drivers/net/sfc/tenxpress.c
@@ -214,7 +214,10 @@ static int tenxpress_special_reset(struct efx_nic *efx)
 {
        int rc, reg;
 
-       EFX_TRACE(efx, "%s\n", __func__);
+       /* The XGMAC clock is driven from the SFC7101/SFT9001 312MHz clock, so
+        * a special software reset can glitch the XGMAC sufficiently for stats
+        * requests to fail. Since we don't ofen special_reset, just lock. */
+       spin_lock(&efx->stats_lock);
 
        /* Initiate reset */
        reg = mdio_clause45_read(efx, efx->mii.phy_id,
@@ -223,20 +226,22 @@ static int tenxpress_special_reset(struct efx_nic *efx)
        mdio_clause45_write(efx, efx->mii.phy_id, MDIO_MMD_PMAPMD,
                            PMA_PMD_EXT_CTRL_REG, reg);
 
-       msleep(200);
+       mdelay(200);
 
        /* Wait for the blocks to come out of reset */
        rc = mdio_clause45_wait_reset_mmds(efx,
                                           TENXPRESS_REQUIRED_DEVS);
        if (rc < 0)
-               return rc;
+               goto unlock;
 
        /* Try and reconfigure the device */
        rc = tenxpress_init(efx);
        if (rc < 0)
-               return rc;
+               goto unlock;
 
-       return 0;
+unlock:
+       spin_unlock(&efx->stats_lock);
+       return rc;
 }
 
 static void tenxpress_set_bad_lp(struct efx_nic *efx, bool bad_lp)