Revert "mv643xx_eth: use longer DMA bursts".

This reverts commit cd4ccf76.

On the Pegasos board, we can't do DMA burst that are longer than
one cache line.  For now, go back to using 32 byte DMA bursts for
all mv643xx_eth platforms -- we can switch the ARM-based platforms
back to doing long 128 byte bursts in the next development cycle.
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Reported-by: Alan Curry <pacman@kosh.dhis.org>
Reported-by: Gabriel Paubert <paubert@iram.es>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/mv643xx_eth.c

@@ -136,21 +136,23 @@ static char mv643xx_eth_driver_version[] = "1.4";
 /*
  * SDMA configuration register.
  */
+#define RX_BURST_SIZE_4_64BIT		(2 << 1)
 #define RX_BURST_SIZE_16_64BIT		(4 << 1)
 #define BLM_RX_NO_SWAP			(1 << 4)
 #define BLM_TX_NO_SWAP			(1 << 5)
+#define TX_BURST_SIZE_4_64BIT		(2 << 22)
 #define TX_BURST_SIZE_16_64BIT		(4 << 22)
 
 #if defined(__BIG_ENDIAN)
 #define PORT_SDMA_CONFIG_DEFAULT_VALUE		\
-		(RX_BURST_SIZE_16_64BIT	|	\
-		TX_BURST_SIZE_16_64BIT)
+		(RX_BURST_SIZE_4_64BIT	|	\
+		 TX_BURST_SIZE_4_64BIT)
 #elif defined(__LITTLE_ENDIAN)
 #define PORT_SDMA_CONFIG_DEFAULT_VALUE		\
-		(RX_BURST_SIZE_16_64BIT	|	\
+		(RX_BURST_SIZE_4_64BIT	|	\
 		 BLM_RX_NO_SWAP		|	\
 		 BLM_TX_NO_SWAP		|	\
-		TX_BURST_SIZE_16_64BIT)
+		 TX_BURST_SIZE_4_64BIT)
 #else
 #error One of __BIG_ENDIAN or __LITTLE_ENDIAN must be defined
 #endif