[PATCH] libata: flush COMRESET set and clear

Updated patch to fix erroneous flush of COMRESET set and missing flush
of COMRESET clear.  Created a new routine scr_write_flush() to try to
prevent this in the future.  Also, this patch is based on libata-2.6
instead of the previous libata-dev-2.6 based patch.

Signed-off-by: Brett Russ <russb@emc.com>

Index: libata-2.6/drivers/scsi/libata-core.c
===================================================================

2 files changed, 10 insertions, 3 deletions

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index f70935cba173..ee9b96da841e 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -1253,11 +1253,11 @@ void __sata_phy_reset(struct ata_port *ap)
         unsigned long timeout = jiffies + (HZ * 5);
 
         if (ap->flags & ATA_FLAG_SATA_RESET) {
-                scr_write(ap, SCR_CONTROL, 0x301); /* issue phy wake/reset */
-                scr_read(ap, SCR_STATUS);       /* dummy read; flush */
+                /* issue phy wake/reset */
+                scr_write_flush(ap, SCR_CONTROL, 0x301);
                 udelay(400);                    /* FIXME: a guess */
         }
-        scr_write(ap, SCR_CONTROL, 0x300);      /* issue phy wake/clear reset */
+        scr_write_flush(ap, SCR_CONTROL, 0x300); /* phy wake/clear reset */
 
         /* wait for phy to become ready, if necessary */
         do {
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 505160ab472b..1f7e2039a04e 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -584,6 +584,13 @@ static inline void scr_write(struct ata_port *ap, unsigned int reg, u32 val)
         ap->ops->scr_write(ap, reg, val);
 }
 
+static inline void scr_write_flush(struct ata_port *ap, unsigned int reg, 
+                                   u32 val)
+{
+        ap->ops->scr_write(ap, reg, val);
+        (void) ap->ops->scr_read(ap, reg);
+}
+
 static inline unsigned int sata_dev_present(struct ata_port *ap)
 {
         return ((scr_read(ap, SCR_STATUS) & 0xf) == 0x3) ? 1 : 0;