[PATCH 1/3] net: macb: Add support for rsc capable hardware

[Rafal Ozieblo <rafalo@cadence.com>]

When the pbuf_rsc has been enabled in hardware
the receive buffer offset for incoming packets
cannot be changed in the network configuration register
(even when rsc is not use at all).

Signed-off-by: Rafal Ozieblo <rafalo@cadence.com>
---
 drivers/net/ethernet/cadence/macb.h      |  2 ++
 drivers/net/ethernet/cadence/macb_main.c | 22 ++++++++++++++++++----
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 8665982..33c9a48 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -477,6 +477,8 @@
 /* Bitfields in DCFG6. */
 #define GEM_PBUF_LSO_OFFSET			27
 #define GEM_PBUF_LSO_SIZE			1
+#define GEM_PBUF_RSC_OFFSET			26
+#define GEM_PBUF_RSC_SIZE			1
 #define GEM_DAW64_OFFSET			23
 #define GEM_DAW64_SIZE				1
 
diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index b4c9268..43201a8 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -930,8 +930,9 @@ static void gem_rx_refill(struct macb_queue *queue)
 			macb_set_addr(bp, desc, paddr);
 			desc->ctrl = 0;
 
-			/* properly align Ethernet header */
-			skb_reserve(skb, NET_IP_ALIGN);
+			if (!(bp->dev->hw_features & NETIF_F_LRO))
+				/* properly align Ethernet header */
+				skb_reserve(skb, NET_IP_ALIGN);
 		} else {
 			desc->addr &= ~MACB_BIT(RX_USED);
 			desc->ctrl = 0;
@@ -2110,7 +2111,13 @@ static void macb_init_hw(struct macb *bp)
 	config = macb_mdc_clk_div(bp);
 	if (bp->phy_interface == PHY_INTERFACE_MODE_SGMII)
 		config |= GEM_BIT(SGMIIEN) | GEM_BIT(PCSSEL);
-	config |= MACB_BF(RBOF, NET_IP_ALIGN);	/* Make eth data aligned */
+	/* When the pbuf_rsc has been enabled in hardware the receive buffer
+	 * offset cannot be changed in the network configuration register.
+	 */
+	if (!(bp->dev->hw_features &  NETIF_F_LRO))
+		/* Make eth data aligned */
+		config |= MACB_BF(RBOF, NET_IP_ALIGN);
+
 	config |= MACB_BIT(PAE);		/* PAuse Enable */
 	config |= MACB_BIT(DRFCS);		/* Discard Rx FCS */
 	if (bp->caps & MACB_CAPS_JUMBO)
@@ -2281,7 +2288,7 @@ static void macb_set_rx_mode(struct net_device *dev)
 static int macb_open(struct net_device *dev)
 {
 	struct macb *bp = netdev_priv(dev);
-	size_t bufsz = dev->mtu + ETH_HLEN + ETH_FCS_LEN + NET_IP_ALIGN;
+	size_t bufsz = dev->mtu + ETH_HLEN + ETH_FCS_LEN;
 	struct macb_queue *queue;
 	unsigned int q;
 	int err;
@@ -2295,6 +2302,9 @@ static int macb_open(struct net_device *dev)
 	if (!dev->phydev)
 		return -EAGAIN;
 
+	if (!(bp->dev->hw_features & NETIF_F_LRO))
+		bufsz += NET_IP_ALIGN;
+
 	/* RX buffers initialization */
 	macb_init_rx_buffer_size(bp, bufsz);
 
@@ -3365,6 +3375,10 @@ static int macb_init(struct platform_device *pdev)
 	if (GEM_BFEXT(PBUF_LSO, gem_readl(bp, DCFG6)))
 		dev->hw_features |= MACB_NETIF_LSO;
 
+	/* Check RSC capability */
+	if (GEM_BFEXT(PBUF_RSC, gem_readl(bp, DCFG6)))
+		dev->hw_features |= NETIF_F_LRO;
+
 	/* Checksum offload is only available on gem with packet buffer */
 	if (macb_is_gem(bp) && !(bp->caps & MACB_CAPS_FIFO_MODE))
 		dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_RXCSUM;
-- 
2.4.5