igb: Add DMA Coalescing feature to driver

This patch add DMA Coalescing which is a power-saving feature that
coalesces DMA writes in order to stay in a low-power state as much
as possible.  Feature is disabled by default.

Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/net/igb/igb_ethtool.c b/drivers/net/igb/igb_ethtool.c
index df15a915bbe..d976733bbcc 100644
--- a/drivers/net/igb/igb_ethtool.c
+++ b/drivers/net/igb/igb_ethtool.c
@@ -2009,6 +2009,12 @@ static int igb_set_coalesce(struct net_device *netdev,
         if ((adapter->flags & IGB_FLAG_QUEUE_PAIRS) && ec->tx_coalesce_usecs)
                 return -EINVAL;
 
+        /* If ITR is disabled, disable DMAC */
+        if (ec->rx_coalesce_usecs == 0) {
+                if (adapter->flags & IGB_FLAG_DMAC)
+                        adapter->flags &= ~IGB_FLAG_DMAC;
+        }
+
         /* convert to rate of irq's per second */
         if (ec->rx_coalesce_usecs && ec->rx_coalesce_usecs <= 3)
                 adapter->rx_itr_setting = ec->rx_coalesce_usecs;