AHCI: speed up resume

During resume, sleep 1 second to wait for the HBA reset
to finish is a waste of time.

According to the AHCI 1.2 spec,
We should poll the HOST_CTL register,
and return error if the host reset is not
finished within 1 second.

Test results show that the HBA reset can be done quickly(in usecs).
And this patch may save nearly 1 second during resume.
Signed-off-by: NZhang Rui <rui.zhang@intel.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

drivers/ata/ahci.c

@@ -1142,12 +1142,15 @@ static int ahci_reset_controller(struct ata_host *host)
 			readl(mmio + HOST_CTL); /* flush */
 		}
 
-		/* reset must complete within 1 second, or
+		/*
+		 * to perform host reset, OS should set HOST_RESET
+		 * and poll until this bit is read to be "0".
+		 * reset must complete within 1 second, or
 		 * the hardware should be considered fried.
 		 */
-		ssleep(1);
+		tmp = ata_wait_register(mmio + HOST_CTL, HOST_RESET,
+					HOST_RESET, 10, 1000);
 
-		tmp = readl(mmio + HOST_CTL);
 		if (tmp & HOST_RESET) {
 			dev_printk(KERN_ERR, host->dev,
 				   "controller reset failed (0x%x)\n", tmp);