libata: implement ata_wait_after_reset()

On certain device/controller combination, 0xff status is asserted
after reset and doesn't get cleared during 150ms post-reset wait.  As
0xff status is interpreted as no device (for good reasons), this can
lead to misdetection on such cases.

This patch implements ata_wait_after_reset() which replaces the 150ms
sleep and waits upto ATA_TMOUT_FF_WAIT if status is 0xff.
ATA_TMOUT_FF_WAIT is currently 800ms which is enough for
HHD424020F7SV00 to get detected but not enough for Quantum GoVault
drive which is known to take upto 2s.

Without parallel probing, spending 2s on 0xff port would incur too
much delay on ata_piix's which use 0xff to indicate empty port and
doesn't have SCR register, so GoVault needs to wait till parallel
probing.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 2 insertions, 9 deletions

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 49cf4cf1a5a2..93bcb2cb3d35 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1153,15 +1153,8 @@ static int ahci_do_softreset(struct ata_link *link, unsigned int *class,
         tf.ctl &= ~ATA_SRST;
         ahci_exec_polled_cmd(ap, pmp, &tf, 0, 0, 0);
 
-        /* spec mandates ">= 2ms" before checking status.
-         * We wait 150ms, because that was the magic delay used for
-         * ATAPI devices in Hale Landis's ATADRVR, for the period of time
-         * between when the ATA command register is written, and then
-         * status is checked.  Because waiting for "a while" before
-         * checking status is fine, post SRST, we perform this magic
-         * delay here as well.
-         */
-        msleep(150);
+        /* wait a while before checking status */
+        ata_wait_after_reset(ap, deadline);
 
         rc = ata_wait_ready(ap, deadline);
         /* link occupied, -ENODEV too is an error */