gianfar: Make all BD status writes 32-bit

Whenever we want to update the status field in a BD, we usually want to
update the length field, too.  By combining them into one 32-bit field, we
reduce the number of stores to memory shared with the controller, and we
eliminate the need for order-enforcement, as the length and "READY" bit are
now updated atomically at the same time.

Signed-off-by: Dai Haruki <Dai.Haruki@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c
index e7e8201283a33b92f78782bdd2c0fd52871b7ed9..3e611a69df132b7a57ddec797a1d785a849383f0 100644 (file)
--- a/drivers/net/gianfar.c
+++ b/drivers/net/gianfar.c
@@ -854,8 +854,7 @@ static void free_skb_resources(struct gfar_private *priv)
                                priv->rx_skbuff[i] = NULL;
                        }
 
-                       rxbdp->status = 0;
-                       rxbdp->length = 0;
+                       rxbdp->lstatus = 0;
                        rxbdp->bufPtr = 0;
 
                        rxbdp++;
@@ -976,8 +975,7 @@ int startup_gfar(struct net_device *dev)
        /* Initialize Transmit Descriptor Ring */
        txbdp = priv->tx_bd_base;
        for (i = 0; i < priv->tx_ring_size; i++) {
-               txbdp->status = 0;
-               txbdp->length = 0;
+               txbdp->lstatus = 0;
                txbdp->bufPtr = 0;
                txbdp++;
        }
@@ -1216,7 +1214,7 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
        struct gfar_private *priv = netdev_priv(dev);
        struct txfcb *fcb = NULL;
        struct txbd8 *txbdp, *base;
-       u16 status;
+       u32 lstatus;
        unsigned long flags;
 
        /* Update transmit stats */
@@ -1230,26 +1228,25 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
        base = priv->tx_bd_base;
 
        /* Clear all but the WRAP status flags */
-       status = txbdp->status & TXBD_WRAP;
+       lstatus = txbdp->lstatus & BD_LFLAG(TXBD_WRAP);
 
        /* Set up checksumming */
        if (CHECKSUM_PARTIAL == skb->ip_summed) {
                fcb = gfar_add_fcb(skb);
-               status |= TXBD_TOE;
+               lstatus |= BD_LFLAG(TXBD_TOE);
                gfar_tx_checksum(skb, fcb);
        }
 
        if (priv->vlgrp && vlan_tx_tag_present(skb)) {
                if (unlikely(NULL == fcb)) {
                        fcb = gfar_add_fcb(skb);
-                       status |= TXBD_TOE;
+                       lstatus |= BD_LFLAG(TXBD_TOE);
                }
 
                gfar_tx_vlan(skb, fcb);
        }
 
        /* Set buffer length and pointer */
-       txbdp->length = skb->len;
        txbdp->bufPtr = dma_map_single(&dev->dev, skb->data,
                        skb->len, DMA_TO_DEVICE);
 
@@ -1260,12 +1257,10 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
        priv->skb_curtx =
            (priv->skb_curtx + 1) & TX_RING_MOD_MASK(priv->tx_ring_size);
 
-       /* Flag the BD as interrupt-causing */
-       status |= TXBD_INTERRUPT;
-
-       /* Flag the BD as ready to go, last in frame, and  */
-       /* in need of CRC */
-       status |= (TXBD_READY | TXBD_LAST | TXBD_CRC);
+       /* Flag the BD as ready, interrupt-causing, last, and in need of CRC */
+       lstatus |=
+               BD_LFLAG(TXBD_READY | TXBD_LAST | TXBD_CRC | TXBD_INTERRUPT) |
+               skb->len;
 
        dev->trans_start = jiffies;
 
@@ -1278,7 +1273,7 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
         */
 
        eieio();
-       txbdp->status = status;
+       txbdp->lstatus = lstatus;
 
        txbdp = next_bd(txbdp, base, priv->tx_ring_size);
 
@@ -1546,20 +1541,19 @@ static void gfar_new_rxbdp(struct net_device *dev, struct rxbd8 *bdp,
                struct sk_buff *skb)
 {
        struct gfar_private *priv = netdev_priv(dev);
-       u32 * status_len = (u32 *)bdp;
-       u16 flags;
+       u32 lstatus;
 
        bdp->bufPtr = dma_map_single(&dev->dev, skb->data,
                        priv->rx_buffer_size, DMA_FROM_DEVICE);
 
-       flags = RXBD_EMPTY | RXBD_INTERRUPT;
+       lstatus = BD_LFLAG(RXBD_EMPTY | RXBD_INTERRUPT);
 
        if (bdp == priv->rx_bd_base + priv->rx_ring_size - 1)
-               flags |= RXBD_WRAP;
+               lstatus |= BD_LFLAG(RXBD_WRAP);
 
        eieio();
 
-       *status_len = (u32)flags << 16;
+       bdp->lstatus = lstatus;
 }
 
 

diff --git a/drivers/net/gianfar.h b/drivers/net/gianfar.h
index 1ebf7ac27a3d6b024d52f0f635bd2f88900a2b1f..9c8974dc8dd5f558b3012629b775730dc0110f98 100644 (file)
--- a/drivers/net/gianfar.h
+++ b/drivers/net/gianfar.h
@@ -311,6 +311,8 @@ extern const char gfar_driver_version[];
 #define ATTRELI_EI_MASK                0x00003fff
 #define ATTRELI_EI(x) (x)
 
+#define BD_LFLAG(flags) ((flags) << 16)
+#define BD_LENGTH_MASK         0x00ff
 
 /* TxBD status field bits */
 #define TXBD_READY             0x8000
@@ -374,8 +376,13 @@ extern const char gfar_driver_version[];
 
 struct txbd8
 {
-       u16     status; /* Status Fields */
-       u16     length; /* Buffer length */
+       union {
+               struct {
+                       u16     status; /* Status Fields */
+                       u16     length; /* Buffer length */
+               };
+               u32 lstatus;
+       };
        u32     bufPtr; /* Buffer Pointer */
 };
 
@@ -390,8 +397,13 @@ struct txfcb {
 
 struct rxbd8
 {
-       u16     status; /* Status Fields */
-       u16     length; /* Buffer Length */
+       union {
+               struct {
+                       u16     status; /* Status Fields */
+                       u16     length; /* Buffer Length */
+               };
+               u32 lstatus;
+       };
        u32     bufPtr; /* Buffer Pointer */
 };