net: axienet: Handle jumbo frames for lesser frame sizes

In the current implementation, jumbo frames are supported only
for the frame sizes > 16K. This patch corrects this logic to
handle jumbo frames for lesser frame sizes (< 16K) ensuring jumbo frame
MTU is within the limit of max frame size configured in the h/w
design.

Signed-off-by: Srikanth Thokala <sthokal@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 27 insertions, 28 deletions

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet.h b/drivers/net/ethernet/xilinx/xilinx_axienet.h
index 4c9b4fa1d3c1..4e309440964a 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet.h
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet.h
@@ -11,16 +11,16 @@
 #include <linux/netdevice.h>
 #include <linux/spinlock.h>
 #include <linux/interrupt.h>
+#include <linux/if_vlan.h>
 
 /* Packet size info */
 #define XAE_HDR_SIZE                    14 /* Size of Ethernet header */
-#define XAE_HDR_VLAN_SIZE               18 /* Size of an Ethernet hdr + VLAN */
 #define XAE_TRL_SIZE                     4 /* Size of Ethernet trailer (FCS) */
 #define XAE_MTU                       1500 /* Max MTU of an Ethernet frame */
 #define XAE_JUMBO_MTU                 9000 /* Max MTU of a jumbo Eth. frame */
 
 #define XAE_MAX_FRAME_SIZE       (XAE_MTU + XAE_HDR_SIZE + XAE_TRL_SIZE)
-#define XAE_MAX_VLAN_FRAME_SIZE  (XAE_MTU + XAE_HDR_VLAN_SIZE + XAE_TRL_SIZE)
+#define XAE_MAX_VLAN_FRAME_SIZE  (XAE_MTU + VLAN_ETH_HLEN + XAE_TRL_SIZE)
 #define XAE_MAX_JUMBO_FRAME_SIZE (XAE_JUMBO_MTU + XAE_HDR_SIZE + XAE_TRL_SIZE)
 
 /* Configuration options */
@@ -407,8 +407,7 @@ struct axidma_bd {
  *                Txed/Rxed in the existing hardware. If jumbo option is
  *                supported, the maximum frame size would be 9k. Else it is
  *                1522 bytes (assuming support for basic VLAN)
- * @jumbo_support: Stores hardware configuration for jumbo support. If hardware
- *                 can handle jumbo packets, this entry will be 1, else 0.
+ * @rxmem:      Stores rx memory size for jumbo frame handling.
  */
 struct axienet_local {
         struct net_device *ndev;
@@ -446,7 +445,7 @@ struct axienet_local {
         u32 rx_bd_ci;
 
         u32 max_frm_size;
-        u32 jumbo_support;
+        u32 rxmem;
 
         int csum_offload_on_tx_path;
         int csum_offload_on_rx_path;
diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index b83425393a24..b1081e1893b0 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -471,14 +471,16 @@ static void axienet_device_reset(struct net_device *ndev)
         __axienet_device_reset(lp, &ndev->dev, XAXIDMA_RX_CR_OFFSET);
 
         lp->max_frm_size = XAE_MAX_VLAN_FRAME_SIZE;
+        lp->options |= XAE_OPTION_VLAN;
         lp->options &= (~XAE_OPTION_JUMBO);
 
         if ((ndev->mtu > XAE_MTU) &&
-            (ndev->mtu <= XAE_JUMBO_MTU) &&
-            (lp->jumbo_support)) {
-                lp->max_frm_size = ndev->mtu + XAE_HDR_VLAN_SIZE +
-                                   XAE_TRL_SIZE;
-                lp->options |= XAE_OPTION_JUMBO;
+                (ndev->mtu <= XAE_JUMBO_MTU)) {
+                lp->max_frm_size = ndev->mtu + VLAN_ETH_HLEN +
+                                        XAE_TRL_SIZE;
+
+                if (lp->max_frm_size <= lp->rxmem)
+                        lp->options |= XAE_OPTION_JUMBO;
         }
 
         if (axienet_dma_bd_init(ndev)) {
@@ -1027,15 +1029,15 @@ static int axienet_change_mtu(struct net_device *ndev, int new_mtu)
 
         if (netif_running(ndev))
                 return -EBUSY;
-        if (lp->jumbo_support) {
-                if ((new_mtu > XAE_JUMBO_MTU) || (new_mtu < 64))
-                        return -EINVAL;
-                ndev->mtu = new_mtu;
-        } else {
-                if ((new_mtu > XAE_MTU) || (new_mtu < 64))
-                        return -EINVAL;
-                ndev->mtu = new_mtu;
-        }
+
+        if ((new_mtu + VLAN_ETH_HLEN +
+                XAE_TRL_SIZE) > lp->rxmem)
+                return -EINVAL;
+
+        if ((new_mtu > XAE_JUMBO_MTU) || (new_mtu < 64))
+                return -EINVAL;
+
+        ndev->mtu = new_mtu;
 
         return 0;
 }
@@ -1556,16 +1558,14 @@ static int axienet_of_probe(struct platform_device *op)
                 }
         }
         /* For supporting jumbo frames, the Axi Ethernet hardware must have
-         * a larger Rx/Tx Memory. Typically, the size must be more than or
-         * equal to 16384 bytes, so that we can enable jumbo option and start
-         * supporting jumbo frames. Here we check for memory allocated for
-         * Rx/Tx in the hardware from the device-tree and accordingly set
-         * flags. */
+         * a larger Rx/Tx Memory. Typically, the size must be large so that
+         * we can enable jumbo option and start supporting jumbo frames.
+         * Here we check for memory allocated for Rx/Tx in the hardware from
+         * the device-tree and accordingly set flags.
+         */
         p = (__be32 *) of_get_property(op->dev.of_node, "xlnx,rxmem", NULL);
-        if (p) {
-                if ((be32_to_cpup(p)) >= 0x4000)
-                        lp->jumbo_support = 1;
-        }
+        if (p)
+                lp->rxmem = be32_to_cpup(p);
         p = (__be32 *) of_get_property(op->dev.of_node, "xlnx,phy-type", NULL);
         if (p)
                 lp->phy_type = be32_to_cpup(p);