gianfar: Implement PAUSE frame generation support

The hardware can automatically generate pause frames when the number
of free buffers drops under a certain threshold, but in order to do this,
the address of the last free buffer needs to be written to a specific
register for each RX queue.

This has to be done in 'gfar_clean_rx_ring' which is called for each
RX queue. In order not to impact performance, by adding a register write
for each incoming packet, this operation is done only when the PAUSE frame
transmission is enabled.

Whenever the link is readjusted, this capability is turned on or off.

Change-Id Ib4751d205a00c0813355cf23c4428bf6dcbda003
Signed-off-by: Matei Pavaluca <matei.pavaluca@freescale.com>

Change-Id: I22a836b86f256128ea1bd39e87902321030f7742
Reviewed-on: http://git.am.freescale.net:8181/23138
Reviewed-by: Richard Schmitt <richard.schmitt@freescale.com>
Tested-by: Review Code-CDREVIEW <CDREVIEW@freescale.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/net/ethernet/freescale/gianfar_ethtool.c b/drivers/net/ethernet/freescale/gianfar_ethtool.c
index c937209..3f6c6ec 100644
--- a/drivers/net/ethernet/freescale/gianfar_ethtool.c
+++ b/drivers/net/ethernet/freescale/gianfar_ethtool.c
@@ -585,8 +585,13 @@ static int gfar_spauseparam(struct net_device *dev,
 			u32 tempval;
 			tempval = gfar_read(&regs->maccfg1);
 			tempval &= ~(MACCFG1_TX_FLOW | MACCFG1_RX_FLOW);
-			if (priv->tx_pause_en)
+
+			priv->tx_actual_en = 0;
+			if (priv->tx_pause_en) {
+				priv->tx_actual_en = 1;
 				tempval |= MACCFG1_TX_FLOW;
+			}
+
 			if (priv->rx_pause_en)
 				tempval |= MACCFG1_RX_FLOW;
 			gfar_write(&regs->maccfg1, tempval);