libata: limit post SRST nsect/lbal wait to ~100ms

After SRST, libata used to wait for nsect/lbal to be set to 1/1 for
the slave device.  However, some ATAPI devices don't set nsect/lbal
after SRST and the wait itself isn't too useful as we're gonna wait
for !BSY right after that anyway.

Before reset-seq update, nsect/lbal wait failure used to be ignored
and caused 30sec delay during detection.  After reset-seq, all
timeouts are considered error conditions making libata fail to detect
such ATAPI devices.

This patch limits nsect/lbal wait to around 100ms.  This should give
acceptable behavior to such ATAPI devices while not disturbing the
heavily used code path too much.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 76aa94f55af9847f5e11f133337718191204e722..047eabd75363a110d56e88edd54d899624ab0c6b 100644 (file)
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -3061,22 +3061,28 @@ static int ata_bus_post_reset(struct ata_port *ap, unsigned int devmask,
                }
        }
 
-       /* if device 1 was found in ata_devchk, wait for
-        * register access, then wait for BSY to clear
+       /* if device 1 was found in ata_devchk, wait for register
+        * access briefly, then wait for BSY to clear.
         */
-       while (dev1) {
-               u8 nsect, lbal;
+       if (dev1) {
+               int i;
 
                ap->ops->dev_select(ap, 1);
-               nsect = ioread8(ioaddr->nsect_addr);
-               lbal = ioread8(ioaddr->lbal_addr);
-               if ((nsect == 1) && (lbal == 1))
-                       break;
-               if (time_after(jiffies, deadline))
-                       return -EBUSY;
-               msleep(50);     /* give drive a breather */
-       }
-       if (dev1) {
+
+               /* Wait for register access.  Some ATAPI devices fail
+                * to set nsect/lbal after reset, so don't waste too
+                * much time on it.  We're gonna wait for !BSY anyway.
+                */
+               for (i = 0; i < 2; i++) {
+                       u8 nsect, lbal;
+
+                       nsect = ioread8(ioaddr->nsect_addr);
+                       lbal = ioread8(ioaddr->lbal_addr);
+                       if ((nsect == 1) && (lbal == 1))
+                               break;
+                       msleep(50);     /* give drive a breather */
+               }
+
                rc = ata_wait_ready(ap, deadline);
                if (rc) {
                        if (rc != -ENODEV)