From: Stephen Hemminger <shemminger@osdl.org>
Date: Tue, 17 Jan 2006 21:43:16 +0000 (-0800)
Subject: [PATCH] sky2: optimize for 32 bit dma
X-Git-Tag: v2.6.16-rc2~366^2~7
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a036119f977eeeae2089ddf5b4759de9ca5fbdb6;p=linux-2.6

[PATCH] sky2: optimize for 32 bit dma

Small optimization, if dma addresses are 32 bits, then high
bits are always zero.

Signed-off-by: Stephen Hemminger <shemminger@osdl.or>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
---

diff --git a/drivers/net/sky2.c b/drivers/net/sky2.c
index 3c5d00403e..92ea915c1d 100644
--- a/drivers/net/sky2.c
+++ b/drivers/net/sky2.c
@@ -745,7 +745,7 @@ static inline struct sky2_rx_le *sky2_next_rx(struct sky2_port *sky2)
 /* Return high part of DMA address (could be 32 or 64 bit) */
 static inline u32 high32(dma_addr_t a)
 {
-	return (a >> 16) >> 16;
+	return sizeof(a) > sizeof(u32) ? (a >> 16) >> 16 : 0;
 }
 
 /* Build description to hardware about buffer */
@@ -1225,7 +1225,7 @@ static int sky2_xmit_frame(struct sk_buff *skb, struct net_device *dev)
 
 		mapping = pci_map_page(hw->pdev, frag->page, frag->page_offset,
 				       frag->size, PCI_DMA_TODEVICE);
-		addr64 = (mapping >> 16) >> 16;
+		addr64 = high32(mapping);
 		if (addr64 != sky2->tx_addr64) {
 			le = get_tx_le(sky2);
 			le->tx.addr = cpu_to_le32(addr64);