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: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 65d4e96..4ff3f03 100644 (file)
--- a/drivers/ata/ahci.c
+++ b/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);