[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, 3 insertions, 0 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index e294731a7edd..5028396029b3 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -2158,6 +2158,7 @@ int ata_down_xfermask_limit(struct ata_device *dev, int force_pio0)
 
 static int ata_dev_set_mode(struct ata_device *dev)
 {
+        struct ata_eh_context *ehc = &dev->ap->eh_context;
         unsigned int err_mask;
         int rc;
 
@@ -2172,7 +2173,9 @@ static int ata_dev_set_mode(struct ata_device *dev)
                 return -EIO;
         }
 
+        ehc->i.flags |= ATA_EHI_POST_SETMODE;
         rc = ata_dev_revalidate(dev, 0);
+        ehc->i.flags &= ~ATA_EHI_POST_SETMODE;
         if (rc)
                 return rc;