libata: restructure SFF post-reset readiness waits

Previously, post-softreset readiness is waited as follows.

1. ata_sff_wait_after_reset() waits for 150ms and then for
   ATA_TMOUT_FF_WAIT if status is 0xff and other conditions meet.

2. ata_bus_softreset() finishes with -ENODEV if status is still 0xff.
   If not, continue to #3.

3. ata_bus_post_reset() waits readiness of dev0 and/or dev1 depending
   on devmask using ata_sff_wait_ready().

And for post-hardreset readiness,

1. ata_sff_wait_after_reset() waits for 150ms and then for
   ATA_TMOUT_FF_WAIT if status is 0xff and other conditions meet.

2. sata_sff_hardreset waits for device readiness using
   ata_sff_wait_ready().

This patch merges and unifies post-reset readiness waits into
ata_sff_wait_ready() and ata_sff_wait_after_reset().

ATA_TMOUT_FF_WAIT handling is merged into ata_sff_wait_ready().  If TF
status is 0xff, link status is unknown and the port is SATA, it will
continue polling till ATA_TMOUT_FF_WAIT.

ata_sff_wait_after_reset() is updated to perform the following steps.

1. waits for 150ms.

2. waits for dev0 readiness using ata_sff_wait_ready().  Note that
   this is done regardless of devmask, as ata_sff_wait_ready() handles
   0xff status correctly, this preserves the original behavior except
   that it may wait longer after softreset if link is online but
   status is 0xff.  This behavior change is very unlikely to cause any
   actual difference and is intended.  It brings softreset behavior to
   that of hardreset.

3. waits for dev1 readiness just the same way ata_bus_post_reset() did.

Now both soft and hard resets call ata_sff_wait_after_reset() after
reset to wait for readiness after resets.  As
ata_sff_wait_after_reset() contains calls to ->sff_dev_select(),
explicit call near the end of sata_sff_hardreset() is removed.

This change makes reset implementation simpler and more consistent.

While at it, make the magical 150ms wait post-reset wait duration a
constant and ata_sff_wait_ready() and ata_sff_wait_after_reset() take
@link instead of @ap.  This is to make them consistent with other
reset helpers and ease core changes.

pata_scc is updated accordingly.

Signed-off-by: Tejun Heo <htejun@gmail.com>

1 files changed, 51 insertions, 40 deletions

diff --git a/drivers/ata/pata_scc.c b/drivers/ata/pata_scc.c
index 2b9da715c704..accc275e74cc 100644
--- a/drivers/ata/pata_scc.c
+++ b/drivers/ata/pata_scc.c
@@ -497,47 +497,68 @@ static unsigned int scc_devchk (struct ata_port *ap,
 }
 
 /**
- *      scc_bus_post_reset - PATA device post reset
+ *      scc_wait_after_reset - wait for devices to become ready after reset
  *
- *      Note: Original code is ata_bus_post_reset().
+ *      Note: Original code is ata_sff_wait_after_reset
  */
 
-static int scc_bus_post_reset(struct ata_port *ap, unsigned int devmask,
-                              unsigned long deadline)
+int scc_wait_after_reset(struct ata_link *link, unsigned int devmask,
+                         unsigned long deadline)
 {
+        struct ata_port *ap = link->ap;
         struct ata_ioports *ioaddr = &ap->ioaddr;
         unsigned int dev0 = devmask & (1 << 0);
         unsigned int dev1 = devmask & (1 << 1);
-        int rc;
+        int rc, ret = 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.
+         *
+         * Old drivers/ide uses the 2mS rule and then waits for ready.
+         */
+        msleep(150);
 
-        /* if device 0 was found in ata_devchk, wait for its
-         * BSY bit to clear
+        /* always check readiness of the master device */
+        rc = ata_sff_wait_ready(link, deadline);
+        /* -ENODEV means the odd clown forgot the D7 pulldown resistor
+         * and TF status is 0xff, bail out on it too.
          */
-        if (dev0) {
-                rc = ata_sff_wait_ready(ap, deadline);
-                if (rc && rc != -ENODEV)
-                        return rc;
-        }
+        if (rc)
+                return rc;
 
-        /* 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->sff_dev_select(ap, 1);
-                nsect = in_be32(ioaddr->nsect_addr);
-                lbal = in_be32(ioaddr->lbal_addr);
-                if ((nsect == 1) && (lbal == 1))
-                        break;
-                if (time_after(jiffies, deadline))
-                        return -EBUSY;
-                msleep(50);     /* give drive a breather */
-        }
-        if (dev1) {
-                rc = ata_sff_wait_ready(ap, deadline);
-                if (rc && rc != -ENODEV)
-                        return rc;
+
+                /* 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 = in_be32(ioaddr->nsect_addr);
+                        lbal = in_be32(ioaddr->lbal_addr);
+                        if ((nsect == 1) && (lbal == 1))
+                                break;
+                        msleep(50);     /* give drive a breather */
+                }
+
+                rc = ata_sff_wait_ready(link, deadline);
+                if (rc) {
+                        if (rc != -ENODEV)
+                                return rc;
+                        ret = rc;
+                }
         }
 
         /* is all this really necessary? */
@@ -547,7 +568,7 @@ static int scc_bus_post_reset(struct ata_port *ap, unsigned int devmask,
         if (dev0)
                 ap->ops->sff_dev_select(ap, 0);
 
-        return 0;
+        return ret;
 }
 
 /**
@@ -570,17 +591,7 @@ static unsigned int scc_bus_softreset(struct ata_port *ap, unsigned int devmask,
         udelay(20);
         out_be32(ioaddr->ctl_addr, ap->ctl);
 
-        /* wait a while before checking status */
-        ata_sff_wait_after_reset(ap, deadline);
-
-        /* Before we perform post reset processing we want to see if
-         * the bus shows 0xFF because the odd clown forgets the D7
-         * pulldown resistor.
-         */
-        if (scc_check_status(ap) == 0xFF)
-                return 0;
-
-        scc_bus_post_reset(ap, devmask, deadline);
+        scc_wait_after_reset(&ap->link, devmask, deadlien);
 
         return 0;
 }