[PATCH] libata: implement ATA_EHI_SETMODE and ATA_EHI_POST_SETMODE

libata EH used to perform ata_set_mode() iff the EH session performed
reset as indicated by ATA_EHI_DID_RESET.  This is incorrect because
->dev_config() called by revalidation is allowed to modify transfer
mode which ata_set_mode() should take care of.  This patch implements
the following two flags.

* ATA_EHI_SETMODE: set during EH to schedule ata_set_mode().  Both new
  device attachment and revalidation set this flag.

* ATA_EHI_POST_SETMODE: set while the device is revalidated after
  ata_set_mode().  Post-setmode revalidation is different from initial
  configuaration and EH revalidation in that ->dev_config() is not
  allowed tune transfer mode.  LLD can use this flag to determine
  whether it's allowed to tune transfer mode.  Note that POST_SETMODE
  ->dev_config() is guaranteed to be preceded by non-POST_SETMODE
  ->dev_config().

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

1 files changed, 11 insertions, 2 deletions

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 7c446442616c..477648801a65 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -1653,6 +1653,11 @@ static int ata_eh_revalidate_and_attach(struct ata_port *ap,
 
                         ata_eh_done(ap, dev, ATA_EH_REVALIDATE);
 
+                        /* Configuration may have changed, reconfigure
+                         * transfer mode.
+                         */
+                        ehc->i.flags |= ATA_EHI_SETMODE;
+
                         /* schedule the scsi_rescan_device() here */
                         queue_work(ata_aux_wq, &(ap->scsi_rescan_task));
                 } else if (dev->class == ATA_DEV_UNKNOWN &&
@@ -1675,6 +1680,9 @@ static int ata_eh_revalidate_and_attach(struct ata_port *ap,
                         spin_lock_irqsave(ap->lock, flags);
                         ap->pflags |= ATA_PFLAG_SCSI_HOTPLUG;
                         spin_unlock_irqrestore(ap->lock, flags);
+
+                        /* new device discovered, configure transfer mode */
+                        ehc->i.flags |= ATA_EHI_SETMODE;
                 }
         }
 
@@ -1990,13 +1998,14 @@ static int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
         if (rc)
                 goto dev_fail;
 
-        /* configure transfer mode if the port has been reset */
-        if (ehc->i.flags & ATA_EHI_DID_RESET) {
+        /* configure transfer mode if necessary */
+        if (ehc->i.flags & ATA_EHI_SETMODE) {
                 rc = ata_set_mode(ap, &dev);
                 if (rc) {
                         down_xfermask = 1;
                         goto dev_fail;
                 }
+                ehc->i.flags &= ~ATA_EHI_SETMODE;
         }
 
         /* suspend devices */