[PATCH] libata-eh-fw: update ata_scsi_error() for new EH

Update ata_scsi_error() for new EH.  ata_scsi_error() is responsible
for claiming timed out qcs and invoking ->error_handler in safe and
synchronized manner.  As the state of the controller is unknown if a
qc has timed out, the port is frozen in such cases.

Note that ata_scsi_timed_out() isn't used for new EH.  This is because
a timed out qc cannot be claimed by EH without freezing the port and
freezing the port in ata_scsi_timed_out() results in unnecessary
abortion of other active qcs.  ata_scsi_timed_out() can be removed
once all drivers are converted to new EH.

While at it, add 'TODO: kill' comments to old EH functions.

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

include/linux/libata.h

@@ -225,6 +225,9 @@ enum {
 	ATA_PORT_PRIMARY	= (1 << 0),
 	ATA_PORT_SECONDARY	= (1 << 1),
 
+	/* max repeat if error condition is still set after ->error_handler */
+	ATA_EH_MAX_REPEAT	= 5,
+
 	/* how hard are we gonna try to probe/recover devices */
 	ATA_PROBE_MAX_TRIES	= 3,
 };