sata_sx4: speed up ECC initialization

ECC initialization takes too long. It writes zeroes by portions
of 4 byte, it takes more than 6 minutes on my machine to initialize
512Mb ECC DIMM module. Change portion to 128Kb - it significantly
reduces initialization time.
Signed-off-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/sata_sx4.c

@@ -193,6 +193,7 @@ enum {
 					  PDC_TIMER_MASK_INT,
 };
 
+#define ECC_ERASE_BUF_SZ (128 * 1024)
 
 struct pdc_port_priv {
 	u8			dimm_buf[(ATA_PRD_SZ * ATA_MAX_PRD) + 512];
@@ -1280,7 +1281,6 @@ static unsigned int pdc20621_dimm_init(struct ata_host *host)
 {
 	int speed, size, length;
 	u32 addr, spd0, pci_status;
-	u32 tmp = 0;
 	u32 time_period = 0;
 	u32 tcount = 0;
 	u32 ticks = 0;
@@ -1395,14 +1395,17 @@ static unsigned int pdc20621_dimm_init(struct ata_host *host)
 	pdc20621_i2c_read(host, PDC_DIMM0_SPD_DEV_ADDRESS,
 			  PDC_DIMM_SPD_TYPE, &spd0);
 	if (spd0 == 0x02) {
+		void *buf;
 		VPRINTK("Start ECC initialization\n");
 		addr = 0;
 		length = size * 1024 * 1024;
+		buf = kzalloc(ECC_ERASE_BUF_SZ, GFP_KERNEL);
 		while (addr < length) {
-			pdc20621_put_to_dimm(host, (void *) &tmp, addr,
-					     sizeof(u32));
-			addr += sizeof(u32);
+			pdc20621_put_to_dimm(host, buf, addr,
+					     ECC_ERASE_BUF_SZ);
+			addr += ECC_ERASE_BUF_SZ;
 		}
+		kfree(buf);
 		VPRINTK("Finish ECC initialization\n");
 	}
 	return 0;