[PATCH] ahci: fix status register check in ahci_softreset

ahci_softreset() used to use ahci_tf_read() which reads D2H_REG area
to check for the Status register.  However, this area is zeroed on
initialization and not set by initial signature FIS.  Replace it with
ahci_check_status().

This bug prevented CLO code from being activated whenever BSY and/or
DRQ is set prior to softreset.  This fix makes
AHCI_FLAG_RESET_NEEDS_CLO flag redundant.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/ata/ahci.c

@@ -736,8 +736,7 @@ static int ahci_softreset(struct ata_port *ap, unsigned int *class)
 	}
 
 	/* check BUSY/DRQ, perform Command List Override if necessary */
-	ahci_tf_read(ap, &tf);
-	if (tf.command & (ATA_BUSY | ATA_DRQ)) {
+	if (ahci_check_status(ap) & (ATA_BUSY | ATA_DRQ)) {
 		rc = ahci_clo(ap);
 
 		if (rc == -EOPNOTSUPP) {