/*
   *  libata-eh.c - libata error handling
   *

   *  Maintained by:  Tejun Heo <tj@kernel.org>

   *    		    Please ALWAYS copy linux-ide@vger.kernel.org
   *		    on emails.
   *
   *  Copyright 2006 Tejun Heo <htejun@gmail.com>
   *
   *
   *  This program is free software; you can redistribute it and/or
   *  modify it under the terms of the GNU General Public License as
   *  published by the Free Software Foundation; either version 2, or
   *  (at your option) any later version.
   *
   *  This program is distributed in the hope that it will be useful,
   *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   *  General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License
   *  along with this program; see the file COPYING.  If not, write to
   *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
   *  USA.
   *
   *
   *  libata documentation is available via 'make {ps|pdf}docs',
   *  as Documentation/DocBook/libata.*
   *
   *  Hardware documentation available from http://www.t13.org/ and
   *  http://www.sata-io.org/
   *
   */

  #include <linux/kernel.h>

  #include <linux/blkdev.h>

  #include <linux/export.h>

  #include <linux/pci.h>

  #include <scsi/scsi.h>
  #include <scsi/scsi_host.h>
  #include <scsi/scsi_eh.h>
  #include <scsi/scsi_device.h>
  #include <scsi/scsi_cmnd.h>

  #include <scsi/scsi_dbg.h>

  #include "../scsi/scsi_transport_api.h"

  
  #include <linux/libata.h>

  #include <trace/events/libata.h>

  #include "libata.h"

  enum {

  	/* speed down verdicts */

  	ATA_EH_SPDN_NCQ_OFF		= (1 << 0),
  	ATA_EH_SPDN_SPEED_DOWN		= (1 << 1),
  	ATA_EH_SPDN_FALLBACK_TO_PIO	= (1 << 2),

  	ATA_EH_SPDN_KEEP_ERRORS		= (1 << 3),

  
  	/* error flags */
  	ATA_EFLAG_IS_IO			= (1 << 0),

  	ATA_EFLAG_DUBIOUS_XFER		= (1 << 1),

  	ATA_EFLAG_OLD_ER                = (1 << 31),

  
  	/* error categories */
  	ATA_ECAT_NONE			= 0,
  	ATA_ECAT_ATA_BUS		= 1,
  	ATA_ECAT_TOUT_HSM		= 2,
  	ATA_ECAT_UNK_DEV		= 3,

  	ATA_ECAT_DUBIOUS_NONE		= 4,
  	ATA_ECAT_DUBIOUS_ATA_BUS	= 5,
  	ATA_ECAT_DUBIOUS_TOUT_HSM	= 6,
  	ATA_ECAT_DUBIOUS_UNK_DEV	= 7,
  	ATA_ECAT_NR			= 8,

  	ATA_EH_CMD_DFL_TIMEOUT		=  5000,

  	/* always put at least this amount of time between resets */
  	ATA_EH_RESET_COOL_DOWN		=  5000,

  	/* Waiting in ->prereset can never be reliable.  It's
  	 * sometimes nice to wait there but it can't be depended upon;
  	 * otherwise, we wouldn't be resetting.  Just give it enough
  	 * time for most drives to spin up.
  	 */
  	ATA_EH_PRERESET_TIMEOUT		= 10000,
  	ATA_EH_FASTDRAIN_INTERVAL	=  3000,

  
  	ATA_EH_UA_TRIES			= 5,

  
  	/* probe speed down parameters, see ata_eh_schedule_probe() */
  	ATA_EH_PROBE_TRIAL_INTERVAL	= 60000,	/* 1 min */
  	ATA_EH_PROBE_TRIALS		= 2,

  };
  
  /* The following table determines how we sequence resets.  Each entry
   * represents timeout for that try.  The first try can be soft or
   * hardreset.  All others are hardreset if available.  In most cases
   * the first reset w/ 10sec timeout should succeed.  Following entries

   * are mostly for error handling, hotplug and those outlier devices that
   * take an exceptionally long time to recover from reset.

   */
  static const unsigned long ata_eh_reset_timeouts[] = {

  	10000,	/* most drives spin up by 10sec */
  	10000,	/* > 99% working drives spin up before 20sec */

  	35000,	/* give > 30 secs of idleness for outlier devices */

  	 5000,	/* and sweet one last chance */

  	ULONG_MAX, /* > 1 min has elapsed, give up */

  };

  static const unsigned long ata_eh_identify_timeouts[] = {
  	 5000,	/* covers > 99% of successes and not too boring on failures */
  	10000,  /* combined time till here is enough even for media access */
  	30000,	/* for true idiots */
  	ULONG_MAX,
  };

  static const unsigned long ata_eh_flush_timeouts[] = {
  	15000,	/* be generous with flush */
  	15000,  /* ditto */
  	30000,	/* and even more generous */
  	ULONG_MAX,
  };

  static const unsigned long ata_eh_other_timeouts[] = {
  	 5000,	/* same rationale as identify timeout */
  	10000,	/* ditto */
  	/* but no merciful 30sec for other commands, it just isn't worth it */
  	ULONG_MAX,
  };
  
  struct ata_eh_cmd_timeout_ent {
  	const u8		*commands;
  	const unsigned long	*timeouts;
  };
  
  /* The following table determines timeouts to use for EH internal
   * commands.  Each table entry is a command class and matches the
   * commands the entry applies to and the timeout table to use.
   *
   * On the retry after a command timed out, the next timeout value from
   * the table is used.  If the table doesn't contain further entries,
   * the last value is used.
   *
   * ehc->cmd_timeout_idx keeps track of which timeout to use per
   * command class, so if SET_FEATURES times out on the first try, the
   * next try will use the second timeout value only for that class.
   */
  #define CMDS(cmds...)	(const u8 []){ cmds, 0 }
  static const struct ata_eh_cmd_timeout_ent
  ata_eh_cmd_timeout_table[ATA_EH_CMD_TIMEOUT_TABLE_SIZE] = {
  	{ .commands = CMDS(ATA_CMD_ID_ATA, ATA_CMD_ID_ATAPI),
  	  .timeouts = ata_eh_identify_timeouts, },
  	{ .commands = CMDS(ATA_CMD_READ_NATIVE_MAX, ATA_CMD_READ_NATIVE_MAX_EXT),
  	  .timeouts = ata_eh_other_timeouts, },
  	{ .commands = CMDS(ATA_CMD_SET_MAX, ATA_CMD_SET_MAX_EXT),
  	  .timeouts = ata_eh_other_timeouts, },
  	{ .commands = CMDS(ATA_CMD_SET_FEATURES),
  	  .timeouts = ata_eh_other_timeouts, },
  	{ .commands = CMDS(ATA_CMD_INIT_DEV_PARAMS),
  	  .timeouts = ata_eh_other_timeouts, },

  	{ .commands = CMDS(ATA_CMD_FLUSH, ATA_CMD_FLUSH_EXT),
  	  .timeouts = ata_eh_flush_timeouts },

  };
  #undef CMDS

  static void __ata_port_freeze(struct ata_port *ap);

  #ifdef CONFIG_PM

  static void ata_eh_handle_port_suspend(struct ata_port *ap);
  static void ata_eh_handle_port_resume(struct ata_port *ap);

  #else /* CONFIG_PM */
  static void ata_eh_handle_port_suspend(struct ata_port *ap)
  { }
  
  static void ata_eh_handle_port_resume(struct ata_port *ap)
  { }

  #endif /* CONFIG_PM */

  static void __ata_ehi_pushv_desc(struct ata_eh_info *ehi, const char *fmt,
  				 va_list args)
  {
  	ehi->desc_len += vscnprintf(ehi->desc + ehi->desc_len,
  				     ATA_EH_DESC_LEN - ehi->desc_len,
  				     fmt, args);
  }
  
  /**
   *	__ata_ehi_push_desc - push error description without adding separator
   *	@ehi: target EHI
   *	@fmt: printf format string
   *
   *	Format string according to @fmt and append it to @ehi->desc.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host lock)
   */
  void __ata_ehi_push_desc(struct ata_eh_info *ehi, const char *fmt, ...)
  {
  	va_list args;
  
  	va_start(args, fmt);
  	__ata_ehi_pushv_desc(ehi, fmt, args);
  	va_end(args);
  }
  
  /**
   *	ata_ehi_push_desc - push error description with separator
   *	@ehi: target EHI
   *	@fmt: printf format string
   *
   *	Format string according to @fmt and append it to @ehi->desc.
   *	If @ehi->desc is not empty, ", " is added in-between.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host lock)
   */
  void ata_ehi_push_desc(struct ata_eh_info *ehi, const char *fmt, ...)
  {
  	va_list args;
  
  	if (ehi->desc_len)
  		__ata_ehi_push_desc(ehi, ", ");
  
  	va_start(args, fmt);
  	__ata_ehi_pushv_desc(ehi, fmt, args);
  	va_end(args);
  }
  
  /**
   *	ata_ehi_clear_desc - clean error description
   *	@ehi: target EHI
   *
   *	Clear @ehi->desc.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host lock)
   */
  void ata_ehi_clear_desc(struct ata_eh_info *ehi)
  {
  	ehi->desc[0] = '\0';
  	ehi->desc_len = 0;
  }

  /**
   *	ata_port_desc - append port description
   *	@ap: target ATA port
   *	@fmt: printf format string
   *
   *	Format string according to @fmt and append it to port
   *	description.  If port description is not empty, " " is added
   *	in-between.  This function is to be used while initializing
   *	ata_host.  The description is printed on host registration.
   *
   *	LOCKING:
   *	None.
   */
  void ata_port_desc(struct ata_port *ap, const char *fmt, ...)
  {
  	va_list args;
  
  	WARN_ON(!(ap->pflags & ATA_PFLAG_INITIALIZING));
  
  	if (ap->link.eh_info.desc_len)
  		__ata_ehi_push_desc(&ap->link.eh_info, " ");
  
  	va_start(args, fmt);
  	__ata_ehi_pushv_desc(&ap->link.eh_info, fmt, args);
  	va_end(args);
  }
  
  #ifdef CONFIG_PCI
  
  /**
   *	ata_port_pbar_desc - append PCI BAR description
   *	@ap: target ATA port
   *	@bar: target PCI BAR
   *	@offset: offset into PCI BAR
   *	@name: name of the area
   *
   *	If @offset is negative, this function formats a string which
   *	contains the name, address, size and type of the BAR and
   *	appends it to the port description.  If @offset is zero or
   *	positive, only name and offsetted address is appended.
   *
   *	LOCKING:
   *	None.
   */
  void ata_port_pbar_desc(struct ata_port *ap, int bar, ssize_t offset,
  			const char *name)
  {
  	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
  	char *type = "";
  	unsigned long long start, len;
  
  	if (pci_resource_flags(pdev, bar) & IORESOURCE_MEM)
  		type = "m";
  	else if (pci_resource_flags(pdev, bar) & IORESOURCE_IO)
  		type = "i";
  
  	start = (unsigned long long)pci_resource_start(pdev, bar);
  	len = (unsigned long long)pci_resource_len(pdev, bar);
  
  	if (offset < 0)
  		ata_port_desc(ap, "%s %s%llu@0x%llx", name, type, len, start);
  	else

  		ata_port_desc(ap, "%s 0x%llx", name,
  				start + (unsigned long long)offset);

  }
  
  #endif /* CONFIG_PCI */

  static int ata_lookup_timeout_table(u8 cmd)
  {
  	int i;
  
  	for (i = 0; i < ATA_EH_CMD_TIMEOUT_TABLE_SIZE; i++) {
  		const u8 *cur;
  
  		for (cur = ata_eh_cmd_timeout_table[i].commands; *cur; cur++)
  			if (*cur == cmd)
  				return i;
  	}
  
  	return -1;
  }
  
  /**
   *	ata_internal_cmd_timeout - determine timeout for an internal command
   *	@dev: target device
   *	@cmd: internal command to be issued
   *
   *	Determine timeout for internal command @cmd for @dev.
   *
   *	LOCKING:
   *	EH context.
   *
   *	RETURNS:
   *	Determined timeout.
   */
  unsigned long ata_internal_cmd_timeout(struct ata_device *dev, u8 cmd)
  {
  	struct ata_eh_context *ehc = &dev->link->eh_context;
  	int ent = ata_lookup_timeout_table(cmd);
  	int idx;
  
  	if (ent < 0)
  		return ATA_EH_CMD_DFL_TIMEOUT;
  
  	idx = ehc->cmd_timeout_idx[dev->devno][ent];
  	return ata_eh_cmd_timeout_table[ent].timeouts[idx];
  }
  
  /**
   *	ata_internal_cmd_timed_out - notification for internal command timeout
   *	@dev: target device
   *	@cmd: internal command which timed out
   *
   *	Notify EH that internal command @cmd for @dev timed out.  This
   *	function should be called only for commands whose timeouts are
   *	determined using ata_internal_cmd_timeout().
   *
   *	LOCKING:
   *	EH context.
   */
  void ata_internal_cmd_timed_out(struct ata_device *dev, u8 cmd)
  {
  	struct ata_eh_context *ehc = &dev->link->eh_context;
  	int ent = ata_lookup_timeout_table(cmd);
  	int idx;
  
  	if (ent < 0)
  		return;
  
  	idx = ehc->cmd_timeout_idx[dev->devno][ent];
  	if (ata_eh_cmd_timeout_table[ent].timeouts[idx + 1] != ULONG_MAX)
  		ehc->cmd_timeout_idx[dev->devno][ent]++;
  }

  static void ata_ering_record(struct ata_ering *ering, unsigned int eflags,

  			     unsigned int err_mask)
  {
  	struct ata_ering_entry *ent;
  
  	WARN_ON(!err_mask);
  
  	ering->cursor++;
  	ering->cursor %= ATA_ERING_SIZE;
  
  	ent = &ering->ring[ering->cursor];

  	ent->eflags = eflags;

  	ent->err_mask = err_mask;
  	ent->timestamp = get_jiffies_64();
  }

  static struct ata_ering_entry *ata_ering_top(struct ata_ering *ering)
  {
  	struct ata_ering_entry *ent = &ering->ring[ering->cursor];
  
  	if (ent->err_mask)
  		return ent;
  	return NULL;
  }

  int ata_ering_map(struct ata_ering *ering,
  		  int (*map_fn)(struct ata_ering_entry *, void *),
  		  void *arg)

  {
  	int idx, rc = 0;
  	struct ata_ering_entry *ent;
  
  	idx = ering->cursor;
  	do {
  		ent = &ering->ring[idx];
  		if (!ent->err_mask)
  			break;
  		rc = map_fn(ent, arg);
  		if (rc)
  			break;
  		idx = (idx - 1 + ATA_ERING_SIZE) % ATA_ERING_SIZE;
  	} while (idx != ering->cursor);
  
  	return rc;
  }

  static int ata_ering_clear_cb(struct ata_ering_entry *ent, void *void_arg)

  {
  	ent->eflags |= ATA_EFLAG_OLD_ER;
  	return 0;
  }
  
  static void ata_ering_clear(struct ata_ering *ering)
  {
  	ata_ering_map(ering, ata_ering_clear_cb, NULL);
  }

  static unsigned int ata_eh_dev_action(struct ata_device *dev)
  {

  	struct ata_eh_context *ehc = &dev->link->eh_context;

  
  	return ehc->i.action | ehc->i.dev_action[dev->devno];
  }

  static void ata_eh_clear_action(struct ata_link *link, struct ata_device *dev,

  				struct ata_eh_info *ehi, unsigned int action)
  {

  	struct ata_device *tdev;

  
  	if (!dev) {
  		ehi->action &= ~action;

  		ata_for_each_dev(tdev, link, ALL)

  			ehi->dev_action[tdev->devno] &= ~action;

  	} else {
  		/* doesn't make sense for port-wide EH actions */
  		WARN_ON(!(action & ATA_EH_PERDEV_MASK));
  
  		/* break ehi->action into ehi->dev_action */
  		if (ehi->action & action) {

  			ata_for_each_dev(tdev, link, ALL)

  				ehi->dev_action[tdev->devno] |=
  					ehi->action & action;

  			ehi->action &= ~action;
  		}
  
  		/* turn off the specified per-dev action */
  		ehi->dev_action[dev->devno] &= ~action;
  	}
  }

  /**

   *	ata_eh_acquire - acquire EH ownership
   *	@ap: ATA port to acquire EH ownership for
   *
   *	Acquire EH ownership for @ap.  This is the basic exclusion
   *	mechanism for ports sharing a host.  Only one port hanging off
   *	the same host can claim the ownership of EH.
   *
   *	LOCKING:
   *	EH context.
   */
  void ata_eh_acquire(struct ata_port *ap)
  {
  	mutex_lock(&ap->host->eh_mutex);
  	WARN_ON_ONCE(ap->host->eh_owner);
  	ap->host->eh_owner = current;
  }
  
  /**
   *	ata_eh_release - release EH ownership
   *	@ap: ATA port to release EH ownership for
   *
   *	Release EH ownership for @ap if the caller.  The caller must
   *	have acquired EH ownership using ata_eh_acquire() previously.
   *
   *	LOCKING:
   *	EH context.
   */
  void ata_eh_release(struct ata_port *ap)
  {
  	WARN_ON_ONCE(ap->host->eh_owner != current);
  	ap->host->eh_owner = NULL;
  	mutex_unlock(&ap->host->eh_mutex);
  }
  
  /**

   *	ata_scsi_timed_out - SCSI layer time out callback
   *	@cmd: timed out SCSI command
   *
   *	Handles SCSI layer timeout.  We race with normal completion of
   *	the qc for @cmd.  If the qc is already gone, we lose and let
   *	the scsi command finish (EH_HANDLED).  Otherwise, the qc has
   *	timed out and EH should be invoked.  Prevent ata_qc_complete()
   *	from finishing it by setting EH_SCHEDULED and return
   *	EH_NOT_HANDLED.
   *

   *	TODO: kill this function once old EH is gone.
   *

   *	LOCKING:
   *	Called from timer context
   *
   *	RETURNS:
   *	EH_HANDLED or EH_NOT_HANDLED
   */

  enum blk_eh_timer_return ata_scsi_timed_out(struct scsi_cmnd *cmd)

  {
  	struct Scsi_Host *host = cmd->device->host;

  	struct ata_port *ap = ata_shost_to_port(host);

  	unsigned long flags;
  	struct ata_queued_cmd *qc;

  	enum blk_eh_timer_return ret;

  
  	DPRINTK("ENTER
  ");

  	if (ap->ops->error_handler) {

  		ret = BLK_EH_NOT_HANDLED;

  		goto out;
  	}

  	ret = BLK_EH_HANDLED;

  	spin_lock_irqsave(ap->lock, flags);

  	qc = ata_qc_from_tag(ap, ap->link.active_tag);

  	if (qc) {
  		WARN_ON(qc->scsicmd != cmd);
  		qc->flags |= ATA_QCFLAG_EH_SCHEDULED;
  		qc->err_mask |= AC_ERR_TIMEOUT;

  		ret = BLK_EH_NOT_HANDLED;

  	}

  	spin_unlock_irqrestore(ap->lock, flags);

   out:

  	DPRINTK("EXIT, ret=%d
  ", ret);
  	return ret;
  }

  static void ata_eh_unload(struct ata_port *ap)
  {
  	struct ata_link *link;
  	struct ata_device *dev;
  	unsigned long flags;
  
  	/* Restore SControl IPM and SPD for the next driver and
  	 * disable attached devices.
  	 */
  	ata_for_each_link(link, ap, PMP_FIRST) {
  		sata_scr_write(link, SCR_CONTROL, link->saved_scontrol & 0xff0);
  		ata_for_each_dev(dev, link, ALL)
  			ata_dev_disable(dev);
  	}
  
  	/* freeze and set UNLOADED */
  	spin_lock_irqsave(ap->lock, flags);
  
  	ata_port_freeze(ap);			/* won't be thawed */
  	ap->pflags &= ~ATA_PFLAG_EH_PENDING;	/* clear pending from freeze */
  	ap->pflags |= ATA_PFLAG_UNLOADED;
  
  	spin_unlock_irqrestore(ap->lock, flags);
  }

  /**
   *	ata_scsi_error - SCSI layer error handler callback
   *	@host: SCSI host on which error occurred
   *
   *	Handles SCSI-layer-thrown error events.
   *
   *	LOCKING:
   *	Inherited from SCSI layer (none, can sleep)
   *
   *	RETURNS:
   *	Zero.
   */

  void ata_scsi_error(struct Scsi_Host *host)

  {

  	struct ata_port *ap = ata_shost_to_port(host);

  	unsigned long flags;

  	LIST_HEAD(eh_work_q);

  
  	DPRINTK("ENTER
  ");

  	spin_lock_irqsave(host->host_lock, flags);
  	list_splice_init(&host->eh_cmd_q, &eh_work_q);
  	spin_unlock_irqrestore(host->host_lock, flags);

  	ata_scsi_cmd_error_handler(host, ap, &eh_work_q);
  
  	/* If we timed raced normal completion and there is nothing to
  	   recover nr_timedout == 0 why exactly are we doing error recovery ? */
  	ata_scsi_port_error_handler(host, ap);
  
  	/* finish or retry handled scmd's and clean up */

  	WARN_ON(!list_empty(&eh_work_q));

  
  	DPRINTK("EXIT
  ");
  }
  
  /**
   * ata_scsi_cmd_error_handler - error callback for a list of commands
   * @host:	scsi host containing the port
   * @ap:		ATA port within the host
   * @eh_work_q:	list of commands to process
   *
   * process the given list of commands and return those finished to the
   * ap->eh_done_q.  This function is the first part of the libata error
   * handler which processes a given list of failed commands.
   */
  void ata_scsi_cmd_error_handler(struct Scsi_Host *host, struct ata_port *ap,
  				struct list_head *eh_work_q)
  {
  	int i;
  	unsigned long flags;

  	/* make sure sff pio task is not running */
  	ata_sff_flush_pio_task(ap);

  	/* synchronize with host lock and sort out timeouts */

  
  	/* For new EH, all qcs are finished in one of three ways -
  	 * normal completion, error completion, and SCSI timeout.

  	 * Both completions can race against SCSI timeout.  When normal

  	 * completion wins, the qc never reaches EH.  When error
  	 * completion wins, the qc has ATA_QCFLAG_FAILED set.
  	 *
  	 * When SCSI timeout wins, things are a bit more complex.
  	 * Normal or error completion can occur after the timeout but
  	 * before this point.  In such cases, both types of
  	 * completions are honored.  A scmd is determined to have
  	 * timed out iff its associated qc is active and not failed.
  	 */
  	if (ap->ops->error_handler) {
  		struct scsi_cmnd *scmd, *tmp;
  		int nr_timedout = 0;

  		spin_lock_irqsave(ap->lock, flags);

  		/* This must occur under the ap->lock as we don't want
  		   a polled recovery to race the real interrupt handler

  		   The lost_interrupt handler checks for any completed but
  		   non-notified command and completes much like an IRQ handler.

  		   We then fall into the error recovery code which will treat
  		   this as if normal completion won the race */
  
  		if (ap->ops->lost_interrupt)
  			ap->ops->lost_interrupt(ap);

  		list_for_each_entry_safe(scmd, tmp, eh_work_q, eh_entry) {

  			struct ata_queued_cmd *qc;
  
  			for (i = 0; i < ATA_MAX_QUEUE; i++) {
  				qc = __ata_qc_from_tag(ap, i);
  				if (qc->flags & ATA_QCFLAG_ACTIVE &&
  				    qc->scsicmd == scmd)
  					break;
  			}
  
  			if (i < ATA_MAX_QUEUE) {
  				/* the scmd has an associated qc */
  				if (!(qc->flags & ATA_QCFLAG_FAILED)) {
  					/* which hasn't failed yet, timeout */
  					qc->err_mask |= AC_ERR_TIMEOUT;
  					qc->flags |= ATA_QCFLAG_FAILED;
  					nr_timedout++;
  				}
  			} else {
  				/* Normal completion occurred after
  				 * SCSI timeout but before this point.
  				 * Successfully complete it.
  				 */
  				scmd->retries = scmd->allowed;
  				scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
  			}
  		}
  
  		/* If we have timed out qcs.  They belong to EH from
  		 * this point but the state of the controller is
  		 * unknown.  Freeze the port to make sure the IRQ
  		 * handler doesn't diddle with those qcs.  This must
  		 * be done atomically w.r.t. setting QCFLAG_FAILED.
  		 */
  		if (nr_timedout)
  			__ata_port_freeze(ap);

  		spin_unlock_irqrestore(ap->lock, flags);

  
  		/* initialize eh_tries */
  		ap->eh_tries = ATA_EH_MAX_TRIES;

  	} else

  		spin_unlock_wait(ap->lock);

  }
  EXPORT_SYMBOL(ata_scsi_cmd_error_handler);
  
  /**
   * ata_scsi_port_error_handler - recover the port after the commands
   * @host:	SCSI host containing the port
   * @ap:		the ATA port
   *
   * Handle the recovery of the port @ap after all the commands
   * have been recovered.
   */
  void ata_scsi_port_error_handler(struct Scsi_Host *host, struct ata_port *ap)
  {
  	unsigned long flags;

  	/* invoke error handler */
  	if (ap->ops->error_handler) {

  		struct ata_link *link;

  		/* acquire EH ownership */
  		ata_eh_acquire(ap);
   repeat:

  		/* kill fast drain timer */
  		del_timer_sync(&ap->fastdrain_timer);

  		/* process port resume request */
  		ata_eh_handle_port_resume(ap);

  		/* fetch & clear EH info */

  		spin_lock_irqsave(ap->lock, flags);

  		ata_for_each_link(link, ap, HOST_FIRST) {

  			struct ata_eh_context *ehc = &link->eh_context;
  			struct ata_device *dev;

  			memset(&link->eh_context, 0, sizeof(link->eh_context));
  			link->eh_context.i = link->eh_info;
  			memset(&link->eh_info, 0, sizeof(link->eh_info));

  			ata_for_each_dev(dev, link, ENABLED) {

  				int devno = dev->devno;
  
  				ehc->saved_xfer_mode[devno] = dev->xfer_mode;
  				if (ata_ncq_enabled(dev))
  					ehc->saved_ncq_enabled |= 1 << devno;
  			}

  		}

  		ap->pflags |= ATA_PFLAG_EH_IN_PROGRESS;
  		ap->pflags &= ~ATA_PFLAG_EH_PENDING;

  		ap->excl_link = NULL;	/* don't maintain exclusion over EH */

  		spin_unlock_irqrestore(ap->lock, flags);

  		/* invoke EH, skip if unloading or suspended */
  		if (!(ap->pflags & (ATA_PFLAG_UNLOADING | ATA_PFLAG_SUSPENDED)))

  			ap->ops->error_handler(ap);

  		else {
  			/* if unloading, commence suicide */
  			if ((ap->pflags & ATA_PFLAG_UNLOADING) &&
  			    !(ap->pflags & ATA_PFLAG_UNLOADED))
  				ata_eh_unload(ap);

  			ata_eh_finish(ap);

  		}

  		/* process port suspend request */
  		ata_eh_handle_port_suspend(ap);

  		/* Exception might have happened after ->error_handler

  		 * recovered the port but before this point.  Repeat
  		 * EH in such case.
  		 */

  		spin_lock_irqsave(ap->lock, flags);

  		if (ap->pflags & ATA_PFLAG_EH_PENDING) {

  			if (--ap->eh_tries) {

  				spin_unlock_irqrestore(ap->lock, flags);

  				goto repeat;
  			}

  			ata_port_err(ap,
  				     "EH pending after %d tries, giving up
  ",
  				     ATA_EH_MAX_TRIES);

  			ap->pflags &= ~ATA_PFLAG_EH_PENDING;

  		}

  		/* this run is complete, make sure EH info is clear */

  		ata_for_each_link(link, ap, HOST_FIRST)

  			memset(&link->eh_info, 0, sizeof(link->eh_info));

  		/* end eh (clear host_eh_scheduled) while holding
  		 * ap->lock such that if exception occurs after this
  		 * point but before EH completion, SCSI midlayer will

  		 * re-initiate EH.
  		 */

  		ap->ops->end_eh(ap);

  		spin_unlock_irqrestore(ap->lock, flags);

  		ata_eh_release(ap);

  	} else {

  		WARN_ON(ata_qc_from_tag(ap, ap->link.active_tag) == NULL);

  		ap->ops->eng_timeout(ap);
  	}

  	scsi_eh_flush_done_q(&ap->eh_done_q);

  	/* clean up */

  	spin_lock_irqsave(ap->lock, flags);

  	if (ap->pflags & ATA_PFLAG_LOADING)

  		ap->pflags &= ~ATA_PFLAG_LOADING;

  	else if (ap->pflags & ATA_PFLAG_SCSI_HOTPLUG)

  		schedule_delayed_work(&ap->hotplug_task, 0);

  
  	if (ap->pflags & ATA_PFLAG_RECOVERED)

  		ata_port_info(ap, "EH complete
  ");

  	ap->pflags &= ~(ATA_PFLAG_SCSI_HOTPLUG | ATA_PFLAG_RECOVERED);

  	/* tell wait_eh that we're done */

  	ap->pflags &= ~ATA_PFLAG_EH_IN_PROGRESS;

  	wake_up_all(&ap->eh_wait_q);

  	spin_unlock_irqrestore(ap->lock, flags);

  }

  EXPORT_SYMBOL_GPL(ata_scsi_port_error_handler);

  
  /**

   *	ata_port_wait_eh - Wait for the currently pending EH to complete
   *	@ap: Port to wait EH for
   *
   *	Wait until the currently pending EH is complete.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   */
  void ata_port_wait_eh(struct ata_port *ap)
  {
  	unsigned long flags;
  	DEFINE_WAIT(wait);
  
   retry:

  	spin_lock_irqsave(ap->lock, flags);

  	while (ap->pflags & (ATA_PFLAG_EH_PENDING | ATA_PFLAG_EH_IN_PROGRESS)) {

  		prepare_to_wait(&ap->eh_wait_q, &wait, TASK_UNINTERRUPTIBLE);

  		spin_unlock_irqrestore(ap->lock, flags);

  		schedule();

  		spin_lock_irqsave(ap->lock, flags);

  	}

  	finish_wait(&ap->eh_wait_q, &wait);

  	spin_unlock_irqrestore(ap->lock, flags);

  
  	/* make sure SCSI EH is complete */

  	if (scsi_host_in_recovery(ap->scsi_host)) {

  		ata_msleep(ap, 10);

  		goto retry;
  	}
  }

  EXPORT_SYMBOL_GPL(ata_port_wait_eh);

  static int ata_eh_nr_in_flight(struct ata_port *ap)
  {
  	unsigned int tag;
  	int nr = 0;
  
  	/* count only non-internal commands */
  	for (tag = 0; tag < ATA_MAX_QUEUE - 1; tag++)
  		if (ata_qc_from_tag(ap, tag))
  			nr++;
  
  	return nr;
  }
  
  void ata_eh_fastdrain_timerfn(unsigned long arg)
  {
  	struct ata_port *ap = (void *)arg;
  	unsigned long flags;
  	int cnt;
  
  	spin_lock_irqsave(ap->lock, flags);
  
  	cnt = ata_eh_nr_in_flight(ap);
  
  	/* are we done? */
  	if (!cnt)
  		goto out_unlock;
  
  	if (cnt == ap->fastdrain_cnt) {
  		unsigned int tag;
  
  		/* No progress during the last interval, tag all
  		 * in-flight qcs as timed out and freeze the port.
  		 */
  		for (tag = 0; tag < ATA_MAX_QUEUE - 1; tag++) {
  			struct ata_queued_cmd *qc = ata_qc_from_tag(ap, tag);
  			if (qc)
  				qc->err_mask |= AC_ERR_TIMEOUT;
  		}
  
  		ata_port_freeze(ap);
  	} else {
  		/* some qcs have finished, give it another chance */
  		ap->fastdrain_cnt = cnt;
  		ap->fastdrain_timer.expires =

  			ata_deadline(jiffies, ATA_EH_FASTDRAIN_INTERVAL);

  		add_timer(&ap->fastdrain_timer);
  	}
  
   out_unlock:
  	spin_unlock_irqrestore(ap->lock, flags);
  }
  
  /**
   *	ata_eh_set_pending - set ATA_PFLAG_EH_PENDING and activate fast drain
   *	@ap: target ATA port
   *	@fastdrain: activate fast drain
   *
   *	Set ATA_PFLAG_EH_PENDING and activate fast drain if @fastdrain
   *	is non-zero and EH wasn't pending before.  Fast drain ensures
   *	that EH kicks in in timely manner.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host lock)
   */
  static void ata_eh_set_pending(struct ata_port *ap, int fastdrain)
  {
  	int cnt;
  
  	/* already scheduled? */
  	if (ap->pflags & ATA_PFLAG_EH_PENDING)
  		return;
  
  	ap->pflags |= ATA_PFLAG_EH_PENDING;
  
  	if (!fastdrain)
  		return;
  
  	/* do we have in-flight qcs? */
  	cnt = ata_eh_nr_in_flight(ap);
  	if (!cnt)
  		return;
  
  	/* activate fast drain */
  	ap->fastdrain_cnt = cnt;

  	ap->fastdrain_timer.expires =
  		ata_deadline(jiffies, ATA_EH_FASTDRAIN_INTERVAL);

  	add_timer(&ap->fastdrain_timer);
  }

  /**
   *	ata_qc_schedule_eh - schedule qc for error handling
   *	@qc: command to schedule error handling for
   *
   *	Schedule error handling for @qc.  EH will kick in as soon as
   *	other commands are drained.
   *
   *	LOCKING:

   *	spin_lock_irqsave(host lock)

   */
  void ata_qc_schedule_eh(struct ata_queued_cmd *qc)
  {
  	struct ata_port *ap = qc->ap;

  	struct request_queue *q = qc->scsicmd->device->request_queue;
  	unsigned long flags;

  
  	WARN_ON(!ap->ops->error_handler);
  
  	qc->flags |= ATA_QCFLAG_FAILED;

  	ata_eh_set_pending(ap, 1);

  
  	/* The following will fail if timeout has already expired.
  	 * ata_scsi_error() takes care of such scmds on EH entry.
  	 * Note that ATA_QCFLAG_FAILED is unconditionally set after
  	 * this function completes.
  	 */

  	spin_lock_irqsave(q->queue_lock, flags);

  	blk_abort_request(qc->scsicmd->request);

  	spin_unlock_irqrestore(q->queue_lock, flags);

  }

  /**

   * ata_std_sched_eh - non-libsas ata_ports issue eh with this common routine
   * @ap: ATA port to schedule EH for

   *

   *	LOCKING: inherited from ata_port_schedule_eh

   *	spin_lock_irqsave(host lock)

   */

  void ata_std_sched_eh(struct ata_port *ap)

  {
  	WARN_ON(!ap->ops->error_handler);

  	if (ap->pflags & ATA_PFLAG_INITIALIZING)
  		return;

  	ata_eh_set_pending(ap, 1);

  	scsi_schedule_eh(ap->scsi_host);

  
  	DPRINTK("port EH scheduled
  ");
  }

  EXPORT_SYMBOL_GPL(ata_std_sched_eh);
  
  /**
   * ata_std_end_eh - non-libsas ata_ports complete eh with this common routine
   * @ap: ATA port to end EH for
   *
   * In the libata object model there is a 1:1 mapping of ata_port to
   * shost, so host fields can be directly manipulated under ap->lock, in
   * the libsas case we need to hold a lock at the ha->level to coordinate
   * these events.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host lock)
   */
  void ata_std_end_eh(struct ata_port *ap)
  {
  	struct Scsi_Host *host = ap->scsi_host;
  
  	host->host_eh_scheduled = 0;
  }
  EXPORT_SYMBOL(ata_std_end_eh);
  
  
  /**
   *	ata_port_schedule_eh - schedule error handling without a qc
   *	@ap: ATA port to schedule EH for
   *
   *	Schedule error handling for @ap.  EH will kick in as soon as
   *	all commands are drained.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host lock)
   */
  void ata_port_schedule_eh(struct ata_port *ap)
  {
  	/* see: ata_std_sched_eh, unless you know better */
  	ap->ops->sched_eh(ap);
  }

  static int ata_do_link_abort(struct ata_port *ap, struct ata_link *link)

  {
  	int tag, nr_aborted = 0;
  
  	WARN_ON(!ap->ops->error_handler);

  	/* we're gonna abort all commands, no need for fast drain */
  	ata_eh_set_pending(ap, 0);

  	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
  		struct ata_queued_cmd *qc = ata_qc_from_tag(ap, tag);

  		if (qc && (!link || qc->dev->link == link)) {

  			qc->flags |= ATA_QCFLAG_FAILED;
  			ata_qc_complete(qc);
  			nr_aborted++;
  		}
  	}
  
  	if (!nr_aborted)
  		ata_port_schedule_eh(ap);
  
  	return nr_aborted;
  }

  /**

   *	ata_link_abort - abort all qc's on the link
   *	@link: ATA link to abort qc's for
   *
   *	Abort all active qc's active on @link and schedule EH.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host lock)
   *
   *	RETURNS:
   *	Number of aborted qc's.
   */
  int ata_link_abort(struct ata_link *link)
  {
  	return ata_do_link_abort(link->ap, link);
  }
  
  /**
   *	ata_port_abort - abort all qc's on the port
   *	@ap: ATA port to abort qc's for
   *
   *	Abort all active qc's of @ap and schedule EH.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host_set lock)
   *
   *	RETURNS:
   *	Number of aborted qc's.
   */
  int ata_port_abort(struct ata_port *ap)
  {
  	return ata_do_link_abort(ap, NULL);
  }
  
  /**

   *	__ata_port_freeze - freeze port
   *	@ap: ATA port to freeze
   *
   *	This function is called when HSM violation or some other
   *	condition disrupts normal operation of the port.  Frozen port
   *	is not allowed to perform any operation until the port is
   *	thawed, which usually follows a successful reset.
   *
   *	ap->ops->freeze() callback can be used for freezing the port
   *	hardware-wise (e.g. mask interrupt and stop DMA engine).  If a
   *	port cannot be frozen hardware-wise, the interrupt handler
   *	must ack and clear interrupts unconditionally while the port
   *	is frozen.
   *
   *	LOCKING:

   *	spin_lock_irqsave(host lock)

   */
  static void __ata_port_freeze(struct ata_port *ap)
  {
  	WARN_ON(!ap->ops->error_handler);
  
  	if (ap->ops->freeze)
  		ap->ops->freeze(ap);

  	ap->pflags |= ATA_PFLAG_FROZEN;

  	DPRINTK("ata%u port frozen
  ", ap->print_id);

  }
  
  /**
   *	ata_port_freeze - abort & freeze port
   *	@ap: ATA port to freeze
   *

   *	Abort and freeze @ap.  The freeze operation must be called
   *	first, because some hardware requires special operations
   *	before the taskfile registers are accessible.

   *
   *	LOCKING:

   *	spin_lock_irqsave(host lock)

   *
   *	RETURNS:
   *	Number of aborted commands.
   */
  int ata_port_freeze(struct ata_port *ap)
  {
  	int nr_aborted;
  
  	WARN_ON(!ap->ops->error_handler);

  	__ata_port_freeze(ap);

  	nr_aborted = ata_port_abort(ap);

  
  	return nr_aborted;
  }
  
  /**

   *	sata_async_notification - SATA async notification handler
   *	@ap: ATA port where async notification is received
   *
   *	Handler to be called when async notification via SDB FIS is
   *	received.  This function schedules EH if necessary.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host lock)
   *
   *	RETURNS:
   *	1 if EH is scheduled, 0 otherwise.
   */
  int sata_async_notification(struct ata_port *ap)
  {
  	u32 sntf;
  	int rc;
  
  	if (!(ap->flags & ATA_FLAG_AN))
  		return 0;
  
  	rc = sata_scr_read(&ap->link, SCR_NOTIFICATION, &sntf);
  	if (rc == 0)
  		sata_scr_write(&ap->link, SCR_NOTIFICATION, sntf);

  	if (!sata_pmp_attached(ap) || rc) {

  		/* PMP is not attached or SNTF is not available */

  		if (!sata_pmp_attached(ap)) {

  			/* PMP is not attached.  Check whether ATAPI
  			 * AN is configured.  If so, notify media
  			 * change.
  			 */
  			struct ata_device *dev = ap->link.device;
  
  			if ((dev->class == ATA_DEV_ATAPI) &&
  			    (dev->flags & ATA_DFLAG_AN))
  				ata_scsi_media_change_notify(dev);
  			return 0;
  		} else {
  			/* PMP is attached but SNTF is not available.
  			 * ATAPI async media change notification is
  			 * not used.  The PMP must be reporting PHY
  			 * status change, schedule EH.
  			 */
  			ata_port_schedule_eh(ap);
  			return 1;
  		}
  	} else {
  		/* PMP is attached and SNTF is available */
  		struct ata_link *link;
  
  		/* check and notify ATAPI AN */

  		ata_for_each_link(link, ap, EDGE) {

  			if (!(sntf & (1 << link->pmp)))
  				continue;
  
  			if ((link->device->class == ATA_DEV_ATAPI) &&
  			    (link->device->flags & ATA_DFLAG_AN))
  				ata_scsi_media_change_notify(link->device);
  		}
  
  		/* If PMP is reporting that PHY status of some
  		 * downstream ports has changed, schedule EH.
  		 */
  		if (sntf & (1 << SATA_PMP_CTRL_PORT)) {
  			ata_port_schedule_eh(ap);
  			return 1;
  		}
  
  		return 0;
  	}
  }
  
  /**

   *	ata_eh_freeze_port - EH helper to freeze port
   *	@ap: ATA port to freeze
   *
   *	Freeze @ap.
   *
   *	LOCKING:
   *	None.
   */
  void ata_eh_freeze_port(struct ata_port *ap)
  {
  	unsigned long flags;
  
  	if (!ap->ops->error_handler)
  		return;

  	spin_lock_irqsave(ap->lock, flags);

  	__ata_port_freeze(ap);

  	spin_unlock_irqrestore(ap->lock, flags);

  }
  
  /**
   *	ata_port_thaw_port - EH helper to thaw port
   *	@ap: ATA port to thaw
   *
   *	Thaw frozen port @ap.
   *
   *	LOCKING:
   *	None.
   */
  void ata_eh_thaw_port(struct ata_port *ap)
  {
  	unsigned long flags;
  
  	if (!ap->ops->error_handler)
  		return;

  	spin_lock_irqsave(ap->lock, flags);

  	ap->pflags &= ~ATA_PFLAG_FROZEN;

  
  	if (ap->ops->thaw)
  		ap->ops->thaw(ap);

  	spin_unlock_irqrestore(ap->lock, flags);

  	DPRINTK("ata%u port thawed
  ", ap->print_id);

  }

  static void ata_eh_scsidone(struct scsi_cmnd *scmd)
  {
  	/* nada */
  }
  
  static void __ata_eh_qc_complete(struct ata_queued_cmd *qc)
  {
  	struct ata_port *ap = qc->ap;
  	struct scsi_cmnd *scmd = qc->scsicmd;
  	unsigned long flags;

  	spin_lock_irqsave(ap->lock, flags);

  	qc->scsidone = ata_eh_scsidone;
  	__ata_qc_complete(qc);
  	WARN_ON(ata_tag_valid(qc->tag));

  	spin_unlock_irqrestore(ap->lock, flags);

  
  	scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
  }
  
  /**
   *	ata_eh_qc_complete - Complete an active ATA command from EH
   *	@qc: Command to complete
   *
   *	Indicate to the mid and upper layers that an ATA command has
   *	completed.  To be used from EH.
   */
  void ata_eh_qc_complete(struct ata_queued_cmd *qc)
  {
  	struct scsi_cmnd *scmd = qc->scsicmd;
  	scmd->retries = scmd->allowed;
  	__ata_eh_qc_complete(qc);
  }
  
  /**
   *	ata_eh_qc_retry - Tell midlayer to retry an ATA command after EH
   *	@qc: Command to retry
   *
   *	Indicate to the mid and upper layers that an ATA command
   *	should be retried.  To be used from EH.
   *
   *	SCSI midlayer limits the number of retries to scmd->allowed.

   *	scmd->allowed is incremented for commands which get retried

   *	due to unrelated failures (qc->err_mask is zero).
   */
  void ata_eh_qc_retry(struct ata_queued_cmd *qc)
  {
  	struct scsi_cmnd *scmd = qc->scsicmd;

  	if (!qc->err_mask)
  		scmd->allowed++;

  	__ata_eh_qc_complete(qc);
  }

  
  /**

   *	ata_dev_disable - disable ATA device
   *	@dev: ATA device to disable
   *
   *	Disable @dev.
   *
   *	Locking:
   *	EH context.
   */
  void ata_dev_disable(struct ata_device *dev)
  {
  	if (!ata_dev_enabled(dev))
  		return;
  
  	if (ata_msg_drv(dev->link->ap))

  		ata_dev_warn(dev, "disabled
  ");

  	ata_acpi_on_disable(dev);
  	ata_down_xfermask_limit(dev, ATA_DNXFER_FORCE_PIO0 | ATA_DNXFER_QUIET);
  	dev->class++;

  
  	/* From now till the next successful probe, ering is used to
  	 * track probe failures.  Clear accumulated device error info.
  	 */
  	ata_ering_clear(&dev->ering);

  }
  
  /**

   *	ata_eh_detach_dev - detach ATA device
   *	@dev: ATA device to detach
   *
   *	Detach @dev.
   *
   *	LOCKING:
   *	None.
   */

  void ata_eh_detach_dev(struct ata_device *dev)

  {

  	struct ata_link *link = dev->link;
  	struct ata_port *ap = link->ap;

  	struct ata_eh_context *ehc = &link->eh_context;

  	unsigned long flags;
  
  	ata_dev_disable(dev);

  	spin_lock_irqsave(ap->lock, flags);

  
  	dev->flags &= ~ATA_DFLAG_DETACH;
  
  	if (ata_scsi_offline_dev(dev)) {
  		dev->flags |= ATA_DFLAG_DETACHED;

  		ap->pflags |= ATA_PFLAG_SCSI_HOTPLUG;

  	}

  	/* clear per-dev EH info */

  	ata_eh_clear_action(link, dev, &link->eh_info, ATA_EH_PERDEV_MASK);
  	ata_eh_clear_action(link, dev, &link->eh_context.i, ATA_EH_PERDEV_MASK);

  	ehc->saved_xfer_mode[dev->devno] = 0;
  	ehc->saved_ncq_enabled &= ~(1 << dev->devno);

  	spin_unlock_irqrestore(ap->lock, flags);

  }
  
  /**

   *	ata_eh_about_to_do - about to perform eh_action

   *	@link: target ATA link

   *	@dev: target ATA dev for per-dev action (can be NULL)

   *	@action: action about to be performed
   *
   *	Called just before performing EH actions to clear related bits

   *	in @link->eh_info such that eh actions are not unnecessarily
   *	repeated.

   *
   *	LOCKING:
   *	None.
   */

  void ata_eh_about_to_do(struct ata_link *link, struct ata_device *dev,
  			unsigned int action)

  {

  	struct ata_port *ap = link->ap;
  	struct ata_eh_info *ehi = &link->eh_info;
  	struct ata_eh_context *ehc = &link->eh_context;

  	unsigned long flags;

  	spin_lock_irqsave(ap->lock, flags);

  	ata_eh_clear_action(link, dev, ehi, action);

  	/* About to take EH action, set RECOVERED.  Ignore actions on
  	 * slave links as master will do them again.
  	 */
  	if (!(ehc->i.flags & ATA_EHI_QUIET) && link != ap->slave_link)

  		ap->pflags |= ATA_PFLAG_RECOVERED;

  	spin_unlock_irqrestore(ap->lock, flags);

  }
  
  /**

   *	ata_eh_done - EH action complete

  *	@ap: target ATA port

   *	@dev: target ATA dev for per-dev action (can be NULL)
   *	@action: action just completed
   *
   *	Called right after performing EH actions to clear related bits

   *	in @link->eh_context.

   *
   *	LOCKING:
   *	None.
   */

  void ata_eh_done(struct ata_link *link, struct ata_device *dev,
  		 unsigned int action)

  {

  	struct ata_eh_context *ehc = &link->eh_context;

  	ata_eh_clear_action(link, dev, &ehc->i, action);

  }
  
  /**

   *	ata_err_string - convert err_mask to descriptive string
   *	@err_mask: error mask to convert to string
   *
   *	Convert @err_mask to descriptive string.  Errors are
   *	prioritized according to severity and only the most severe
   *	error is reported.
   *
   *	LOCKING:
   *	None.
   *
   *	RETURNS:
   *	Descriptive string for @err_mask
   */

  static const char *ata_err_string(unsigned int err_mask)

  {
  	if (err_mask & AC_ERR_HOST_BUS)
  		return "host bus error";
  	if (err_mask & AC_ERR_ATA_BUS)
  		return "ATA bus error";
  	if (err_mask & AC_ERR_TIMEOUT)
  		return "timeout";
  	if (err_mask & AC_ERR_HSM)
  		return "HSM violation";
  	if (err_mask & AC_ERR_SYSTEM)
  		return "internal error";
  	if (err_mask & AC_ERR_MEDIA)
  		return "media error";
  	if (err_mask & AC_ERR_INVALID)
  		return "invalid argument";
  	if (err_mask & AC_ERR_DEV)
  		return "device error";
  	return "unknown error";
  }
  
  /**

   *	ata_read_log_page - read a specific log page
   *	@dev: target device

   *	@log: log to read

   *	@page: page to read
   *	@buf: buffer to store read page
   *	@sectors: number of sectors to read
   *
   *	Read log page using READ_LOG_EXT command.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   *
   *	RETURNS:
   *	0 on success, AC_ERR_* mask otherwise.
   */

  unsigned int ata_read_log_page(struct ata_device *dev, u8 log,
  			       u8 page, void *buf, unsigned int sectors)

  {

  	unsigned long ap_flags = dev->link->ap->flags;

  	struct ata_taskfile tf;
  	unsigned int err_mask;

  	bool dma = false;

  	DPRINTK("read log page - log 0x%x, page 0x%x
  ", log, page);

  	/*
  	 * Return error without actually issuing the command on controllers
  	 * which e.g. lockup on a read log page.
  	 */
  	if (ap_flags & ATA_FLAG_NO_LOG_PAGE)
  		return AC_ERR_DEV;

  retry:

  	ata_tf_init(dev, &tf);

  	if (dev->dma_mode && ata_id_has_read_log_dma_ext(dev->id) &&
  	    !(dev->horkage & ATA_HORKAGE_NO_NCQ_LOG)) {

  		tf.command = ATA_CMD_READ_LOG_DMA_EXT;
  		tf.protocol = ATA_PROT_DMA;

  		dma = true;

  	} else {
  		tf.command = ATA_CMD_READ_LOG_EXT;
  		tf.protocol = ATA_PROT_PIO;

  		dma = false;

  	}

  	tf.lbal = log;
  	tf.lbam = page;

  	tf.nsect = sectors;
  	tf.hob_nsect = sectors >> 8;
  	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_LBA48 | ATA_TFLAG_DEVICE;

  
  	err_mask = ata_exec_internal(dev, &tf, NULL, DMA_FROM_DEVICE,

  				     buf, sectors * ATA_SECT_SIZE, 0);

  	if (err_mask && dma) {
  		dev->horkage |= ATA_HORKAGE_NO_NCQ_LOG;
  		ata_dev_warn(dev, "READ LOG DMA EXT failed, trying unqueued
  ");
  		goto retry;
  	}

  	DPRINTK("EXIT, err_mask=%x
  ", err_mask);
  	return err_mask;
  }
  
  /**
   *	ata_eh_read_log_10h - Read log page 10h for NCQ error details
   *	@dev: Device to read log page 10h from
   *	@tag: Resulting tag of the failed command
   *	@tf: Resulting taskfile registers of the failed command
   *
   *	Read log page 10h to obtain NCQ error details and clear error
   *	condition.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   *
   *	RETURNS:
   *	0 on success, -errno otherwise.
   */
  static int ata_eh_read_log_10h(struct ata_device *dev,
  			       int *tag, struct ata_taskfile *tf)
  {

  	u8 *buf = dev->link->ap->sector_buf;

  	unsigned int err_mask;
  	u8 csum;
  	int i;

  	err_mask = ata_read_log_page(dev, ATA_LOG_SATA_NCQ, 0, buf, 1);

  	if (err_mask)
  		return -EIO;
  
  	csum = 0;
  	for (i = 0; i < ATA_SECT_SIZE; i++)
  		csum += buf[i];
  	if (csum)

  		ata_dev_warn(dev, "invalid checksum 0x%x on log page 10h
  ",
  			     csum);

  
  	if (buf[0] & 0x80)
  		return -ENOENT;
  
  	*tag = buf[0] & 0x1f;
  
  	tf->command = buf[2];
  	tf->feature = buf[3];
  	tf->lbal = buf[4];
  	tf->lbam = buf[5];
  	tf->lbah = buf[6];
  	tf->device = buf[7];
  	tf->hob_lbal = buf[8];
  	tf->hob_lbam = buf[9];
  	tf->hob_lbah = buf[10];
  	tf->nsect = buf[12];
  	tf->hob_nsect = buf[13];

  	if (ata_id_has_ncq_autosense(dev->id))
  		tf->auxiliary = buf[14] << 16 | buf[15] << 8 | buf[16];

  
  	return 0;
  }
  
  /**

   *	atapi_eh_tur - perform ATAPI TEST_UNIT_READY
   *	@dev: target ATAPI device
   *	@r_sense_key: out parameter for sense_key
   *
   *	Perform ATAPI TEST_UNIT_READY.
   *
   *	LOCKING:
   *	EH context (may sleep).
   *
   *	RETURNS:
   *	0 on success, AC_ERR_* mask on failure.
   */

  unsigned int atapi_eh_tur(struct ata_device *dev, u8 *r_sense_key)

  {
  	u8 cdb[ATAPI_CDB_LEN] = { TEST_UNIT_READY, 0, 0, 0, 0, 0 };
  	struct ata_taskfile tf;
  	unsigned int err_mask;
  
  	ata_tf_init(dev, &tf);
  
  	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
  	tf.command = ATA_CMD_PACKET;
  	tf.protocol = ATAPI_PROT_NODATA;
  
  	err_mask = ata_exec_internal(dev, &tf, cdb, DMA_NONE, NULL, 0, 0);
  	if (err_mask == AC_ERR_DEV)
  		*r_sense_key = tf.feature >> 4;
  	return err_mask;
  }
  
  /**

   *	ata_eh_request_sense - perform REQUEST_SENSE_DATA_EXT
   *	@dev: device to perform REQUEST_SENSE_SENSE_DATA_EXT to
   *	@cmd: scsi command for which the sense code should be set
   *
   *	Perform REQUEST_SENSE_DATA_EXT after the device reported CHECK
   *	SENSE.  This function is an EH helper.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   */
  static void ata_eh_request_sense(struct ata_queued_cmd *qc,
  				 struct scsi_cmnd *cmd)
  {
  	struct ata_device *dev = qc->dev;
  	struct ata_taskfile tf;
  	unsigned int err_mask;
  
  	if (qc->ap->pflags & ATA_PFLAG_FROZEN) {
  		ata_dev_warn(dev, "sense data available but port frozen
  ");
  		return;
  	}

  	if (!cmd || qc->flags & ATA_QCFLAG_SENSE_VALID)

  		return;
  
  	if (!ata_id_sense_reporting_enabled(dev->id)) {
  		ata_dev_warn(qc->dev, "sense data reporting disabled
  ");
  		return;
  	}
  
  	DPRINTK("ATA request sense
  ");
  
  	ata_tf_init(dev, &tf);
  	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
  	tf.flags |= ATA_TFLAG_LBA | ATA_TFLAG_LBA48;
  	tf.command = ATA_CMD_REQ_SENSE_DATA;
  	tf.protocol = ATA_PROT_NODATA;
  
  	err_mask = ata_exec_internal(dev, &tf, NULL, DMA_NONE, NULL, 0, 0);
  	/* Ignore err_mask; ATA_ERR might be set */
  	if (tf.command & ATA_SENSE) {

  		ata_scsi_set_sense(dev, cmd, tf.lbah, tf.lbam, tf.lbal);

  		qc->flags |= ATA_QCFLAG_SENSE_VALID;
  	} else {
  		ata_dev_warn(dev, "request sense failed stat %02x emask %x
  ",
  			     tf.command, err_mask);
  	}
  }
  
  /**

   *	atapi_eh_request_sense - perform ATAPI REQUEST_SENSE
   *	@dev: device to perform REQUEST_SENSE to
   *	@sense_buf: result sense data buffer (SCSI_SENSE_BUFFERSIZE bytes long)

   *	@dfl_sense_key: default sense key to use

   *
   *	Perform ATAPI REQUEST_SENSE after the device reported CHECK
   *	SENSE.  This function is EH helper.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   *
   *	RETURNS:
   *	0 on success, AC_ERR_* mask on failure
   */

  unsigned int atapi_eh_request_sense(struct ata_device *dev,

  					   u8 *sense_buf, u8 dfl_sense_key)

  {

  	u8 cdb[ATAPI_CDB_LEN] =
  		{ REQUEST_SENSE, 0, 0, 0, SCSI_SENSE_BUFFERSIZE, 0 };

  	struct ata_port *ap = dev->link->ap;

  	struct ata_taskfile tf;

  
  	DPRINTK("ATAPI request sense
  ");

  	memset(sense_buf, 0, SCSI_SENSE_BUFFERSIZE);

  	/* initialize sense_buf with the error register,
  	 * for the case where they are -not- overwritten
  	 */

  	sense_buf[0] = 0x70;

  	sense_buf[2] = dfl_sense_key;

  	/* some devices time out if garbage left in tf */

  	ata_tf_init(dev, &tf);

  	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
  	tf.command = ATA_CMD_PACKET;
  
  	/* is it pointless to prefer PIO for "safety reasons"? */
  	if (ap->flags & ATA_FLAG_PIO_DMA) {

  		tf.protocol = ATAPI_PROT_DMA;

  		tf.feature |= ATAPI_PKT_DMA;
  	} else {

  		tf.protocol = ATAPI_PROT_PIO;

  		tf.lbam = SCSI_SENSE_BUFFERSIZE;
  		tf.lbah = 0;

  	}
  
  	return ata_exec_internal(dev, &tf, cdb, DMA_FROM_DEVICE,

  				 sense_buf, SCSI_SENSE_BUFFERSIZE, 0);

  }
  
  /**
   *	ata_eh_analyze_serror - analyze SError for a failed port

   *	@link: ATA link to analyze SError for

   *
   *	Analyze SError if available and further determine cause of
   *	failure.
   *
   *	LOCKING:
   *	None.
   */

  static void ata_eh_analyze_serror(struct ata_link *link)

  {

  	struct ata_eh_context *ehc = &link->eh_context;

  	u32 serror = ehc->i.serror;
  	unsigned int err_mask = 0, action = 0;

  	u32 hotplug_mask;

  	if (serror & (SERR_PERSISTENT | SERR_DATA)) {

  		err_mask |= AC_ERR_ATA_BUS;

  		action |= ATA_EH_RESET;

  	}
  	if (serror & SERR_PROTOCOL) {
  		err_mask |= AC_ERR_HSM;

  		action |= ATA_EH_RESET;

  	}
  	if (serror & SERR_INTERNAL) {
  		err_mask |= AC_ERR_SYSTEM;

  		action |= ATA_EH_RESET;

  	}

  
  	/* Determine whether a hotplug event has occurred.  Both
  	 * SError.N/X are considered hotplug events for enabled or
  	 * host links.  For disabled PMP links, only N bit is
  	 * considered as X bit is left at 1 for link plugging.
  	 */

  	if (link->lpm_policy > ATA_LPM_MAX_POWER)

  		hotplug_mask = 0;	/* hotplug doesn't work w/ LPM */
  	else if (!(link->flags & ATA_LFLAG_DISABLED) || ata_is_host_link(link))

  		hotplug_mask = SERR_PHYRDY_CHG | SERR_DEV_XCHG;
  	else
  		hotplug_mask = SERR_PHYRDY_CHG;
  
  	if (serror & hotplug_mask)

  		ata_ehi_hotplugged(&ehc->i);

  
  	ehc->i.err_mask |= err_mask;
  	ehc->i.action |= action;
  }
  
  /**

   *	ata_eh_analyze_ncq_error - analyze NCQ error

   *	@link: ATA link to analyze NCQ error for

   *
   *	Read log page 10h, determine the offending qc and acquire
   *	error status TF.  For NCQ device errors, all LLDDs have to do
   *	is setting AC_ERR_DEV in ehi->err_mask.  This function takes
   *	care of the rest.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   */

  void ata_eh_analyze_ncq_error(struct ata_link *link)

  {

  	struct ata_port *ap = link->ap;
  	struct ata_eh_context *ehc = &link->eh_context;
  	struct ata_device *dev = link->device;

  	struct ata_queued_cmd *qc;
  	struct ata_taskfile tf;
  	int tag, rc;
  
  	/* if frozen, we can't do much */

  	if (ap->pflags & ATA_PFLAG_FROZEN)

  		return;
  
  	/* is it NCQ device error? */

  	if (!link->sactive || !(ehc->i.err_mask & AC_ERR_DEV))

  		return;
  
  	/* has LLDD analyzed already? */
  	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
  		qc = __ata_qc_from_tag(ap, tag);
  
  		if (!(qc->flags & ATA_QCFLAG_FAILED))
  			continue;
  
  		if (qc->err_mask)
  			return;
  	}
  
  	/* okay, this error is ours */

  	memset(&tf, 0, sizeof(tf));

  	rc = ata_eh_read_log_10h(dev, &tag, &tf);
  	if (rc) {

  		ata_link_err(link, "failed to read log page 10h (errno=%d)
  ",
  			     rc);

  		return;
  	}

  	if (!(link->sactive & (1 << tag))) {

  		ata_link_err(link, "log page 10h reported inactive tag %d
  ",
  			     tag);

  		return;
  	}
  
  	/* we've got the perpetrator, condemn it */
  	qc = __ata_qc_from_tag(ap, tag);
  	memcpy(&qc->result_tf, &tf, sizeof(tf));

  	qc->result_tf.flags = ATA_TFLAG_ISADDR | ATA_TFLAG_LBA | ATA_TFLAG_LBA48;

  	qc->err_mask |= AC_ERR_DEV | AC_ERR_NCQ;

  	if ((qc->result_tf.command & ATA_SENSE) || qc->result_tf.auxiliary) {

  		char sense_key, asc, ascq;
  
  		sense_key = (qc->result_tf.auxiliary >> 16) & 0xff;
  		asc = (qc->result_tf.auxiliary >> 8) & 0xff;
  		ascq = qc->result_tf.auxiliary & 0xff;

  		ata_scsi_set_sense(dev, qc->scsicmd, sense_key, asc, ascq);

  		ata_scsi_set_sense_information(dev, qc->scsicmd,
  					       &qc->result_tf);

  		qc->flags |= ATA_QCFLAG_SENSE_VALID;
  	}

  	ehc->i.err_mask &= ~AC_ERR_DEV;
  }
  
  /**

   *	ata_eh_analyze_tf - analyze taskfile of a failed qc
   *	@qc: qc to analyze
   *	@tf: Taskfile registers to analyze
   *
   *	Analyze taskfile of @qc and further determine cause of
   *	failure.  This function also requests ATAPI sense data if

   *	available.

   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   *
   *	RETURNS:
   *	Determined recovery action
   */
  static unsigned int ata_eh_analyze_tf(struct ata_queued_cmd *qc,
  				      const struct ata_taskfile *tf)
  {
  	unsigned int tmp, action = 0;
  	u8 stat = tf->command, err = tf->feature;
  
  	if ((stat & (ATA_BUSY | ATA_DRQ | ATA_DRDY)) != ATA_DRDY) {
  		qc->err_mask |= AC_ERR_HSM;

  		return ATA_EH_RESET;

  	}

  	if (stat & (ATA_ERR | ATA_DF)) {

  		qc->err_mask |= AC_ERR_DEV;

  		/*
  		 * Sense data reporting does not work if the
  		 * device fault bit is set.
  		 */
  		if (stat & ATA_DF)
  			stat &= ~ATA_SENSE;
  	} else {

  		return 0;

  	}

  
  	switch (qc->dev->class) {
  	case ATA_DEV_ATA:

  	case ATA_DEV_ZAC:

  		if (stat & ATA_SENSE)
  			ata_eh_request_sense(qc, qc->scsicmd);

  		if (err & ATA_ICRC)
  			qc->err_mask |= AC_ERR_ATA_BUS;

  		if (err & (ATA_UNC | ATA_AMNF))

  			qc->err_mask |= AC_ERR_MEDIA;
  		if (err & ATA_IDNF)
  			qc->err_mask |= AC_ERR_INVALID;
  		break;
  
  	case ATA_DEV_ATAPI:

  		if (!(qc->ap->pflags & ATA_PFLAG_FROZEN)) {

  			tmp = atapi_eh_request_sense(qc->dev,
  						qc->scsicmd->sense_buffer,
  						qc->result_tf.feature >> 4);

  			if (!tmp)

  				qc->flags |= ATA_QCFLAG_SENSE_VALID;

  			else

  				qc->err_mask |= tmp;
  		}

  	}

  	if (qc->flags & ATA_QCFLAG_SENSE_VALID) {
  		int ret = scsi_check_sense(qc->scsicmd);
  		/*
  		 * SUCCESS here means that the sense code could
  		 * evaluated and should be passed to the upper layers
  		 * for correct evaluation.
  		 * FAILED means the sense code could not interpreted
  		 * and the device would need to be reset.
  		 * NEEDS_RETRY and ADD_TO_MLQUEUE means that the
  		 * command would need to be retried.
  		 */
  		if (ret == NEEDS_RETRY || ret == ADD_TO_MLQUEUE) {
  			qc->flags |= ATA_QCFLAG_RETRY;
  			qc->err_mask |= AC_ERR_OTHER;
  		} else if (ret != SUCCESS) {
  			qc->err_mask |= AC_ERR_HSM;
  		}
  	}

  	if (qc->err_mask & (AC_ERR_HSM | AC_ERR_TIMEOUT | AC_ERR_ATA_BUS))

  		action |= ATA_EH_RESET;

  
  	return action;
  }

  static int ata_eh_categorize_error(unsigned int eflags, unsigned int err_mask,
  				   int *xfer_ok)

  {

  	int base = 0;
  
  	if (!(eflags & ATA_EFLAG_DUBIOUS_XFER))
  		*xfer_ok = 1;
  
  	if (!*xfer_ok)

  		base = ATA_ECAT_DUBIOUS_NONE;

  	if (err_mask & AC_ERR_ATA_BUS)

  		return base + ATA_ECAT_ATA_BUS;

  	if (err_mask & AC_ERR_TIMEOUT)

  		return base + ATA_ECAT_TOUT_HSM;

  	if (eflags & ATA_EFLAG_IS_IO) {

  		if (err_mask & AC_ERR_HSM)

  			return base + ATA_ECAT_TOUT_HSM;

  		if ((err_mask &
  		     (AC_ERR_DEV|AC_ERR_MEDIA|AC_ERR_INVALID)) == AC_ERR_DEV)

  			return base + ATA_ECAT_UNK_DEV;

  	}
  
  	return 0;
  }

  struct speed_down_verdict_arg {

  	u64 since;

  	int xfer_ok;

  	int nr_errors[ATA_ECAT_NR];

  };

  static int speed_down_verdict_cb(struct ata_ering_entry *ent, void *void_arg)

  {

  	struct speed_down_verdict_arg *arg = void_arg;

  	int cat;

  	if ((ent->eflags & ATA_EFLAG_OLD_ER) || (ent->timestamp < arg->since))

  		return -1;

  	cat = ata_eh_categorize_error(ent->eflags, ent->err_mask,
  				      &arg->xfer_ok);

  	arg->nr_errors[cat]++;

  	return 0;
  }
  
  /**

   *	ata_eh_speed_down_verdict - Determine speed down verdict

   *	@dev: Device of interest
   *
   *	This function examines error ring of @dev and determines

   *	whether NCQ needs to be turned off, transfer speed should be
   *	stepped down, or falling back to PIO is necessary.

   *

   *	ECAT_ATA_BUS	: ATA_BUS error for any command
   *
   *	ECAT_TOUT_HSM	: TIMEOUT for any command or HSM violation for
   *			  IO commands
   *
   *	ECAT_UNK_DEV	: Unknown DEV error for IO commands
   *

   *	ECAT_DUBIOUS_*	: Identical to above three but occurred while
   *			  data transfer hasn't been verified.
   *

   *	Verdicts are
   *
   *	NCQ_OFF		: Turn off NCQ.

   *

   *	SPEED_DOWN	: Speed down transfer speed but don't fall back
   *			  to PIO.

   *

   *	FALLBACK_TO_PIO	: Fall back to PIO.

   *

   *	Even if multiple verdicts are returned, only one action is

   *	taken per error.  An action triggered by non-DUBIOUS errors
   *	clears ering, while one triggered by DUBIOUS_* errors doesn't.
   *	This is to expedite speed down decisions right after device is
   *	initially configured.
   *
   *	The followings are speed down rules.  #1 and #2 deal with
   *	DUBIOUS errors.

   *

   *	1. If more than one DUBIOUS_ATA_BUS or DUBIOUS_TOUT_HSM errors
   *	   occurred during last 5 mins, SPEED_DOWN and FALLBACK_TO_PIO.
   *
   *	2. If more than one DUBIOUS_TOUT_HSM or DUBIOUS_UNK_DEV errors
   *	   occurred during last 5 mins, NCQ_OFF.
   *
   *	3. If more than 8 ATA_BUS, TOUT_HSM or UNK_DEV errors

   *	   occurred during last 5 mins, FALLBACK_TO_PIO

   *

   *	4. If more than 3 TOUT_HSM or UNK_DEV errors occurred

   *	   during last 10 mins, NCQ_OFF.
   *

   *	5. If more than 3 ATA_BUS or TOUT_HSM errors, or more than 6

   *	   UNK_DEV errors occurred during last 10 mins, SPEED_DOWN.

   *

   *	LOCKING:
   *	Inherited from caller.
   *
   *	RETURNS:

   *	OR of ATA_EH_SPDN_* flags.

   */

  static unsigned int ata_eh_speed_down_verdict(struct ata_device *dev)

  {

  	const u64 j5mins = 5LLU * 60 * HZ, j10mins = 10LLU * 60 * HZ;
  	u64 j64 = get_jiffies_64();
  	struct speed_down_verdict_arg arg;
  	unsigned int verdict = 0;

  	/* scan past 5 mins of error history */

  	memset(&arg, 0, sizeof(arg));

  	arg.since = j64 - min(j64, j5mins);

  	ata_ering_map(&dev->ering, speed_down_verdict_cb, &arg);

  	if (arg.nr_errors[ATA_ECAT_DUBIOUS_ATA_BUS] +
  	    arg.nr_errors[ATA_ECAT_DUBIOUS_TOUT_HSM] > 1)
  		verdict |= ATA_EH_SPDN_SPEED_DOWN |
  			ATA_EH_SPDN_FALLBACK_TO_PIO | ATA_EH_SPDN_KEEP_ERRORS;
  
  	if (arg.nr_errors[ATA_ECAT_DUBIOUS_TOUT_HSM] +
  	    arg.nr_errors[ATA_ECAT_DUBIOUS_UNK_DEV] > 1)
  		verdict |= ATA_EH_SPDN_NCQ_OFF | ATA_EH_SPDN_KEEP_ERRORS;

  	if (arg.nr_errors[ATA_ECAT_ATA_BUS] +
  	    arg.nr_errors[ATA_ECAT_TOUT_HSM] +

  	    arg.nr_errors[ATA_ECAT_UNK_DEV] > 6)

  		verdict |= ATA_EH_SPDN_FALLBACK_TO_PIO;

  	/* scan past 10 mins of error history */

  	memset(&arg, 0, sizeof(arg));

  	arg.since = j64 - min(j64, j10mins);

  	ata_ering_map(&dev->ering, speed_down_verdict_cb, &arg);

  	if (arg.nr_errors[ATA_ECAT_TOUT_HSM] +
  	    arg.nr_errors[ATA_ECAT_UNK_DEV] > 3)
  		verdict |= ATA_EH_SPDN_NCQ_OFF;
  
  	if (arg.nr_errors[ATA_ECAT_ATA_BUS] +
  	    arg.nr_errors[ATA_ECAT_TOUT_HSM] > 3 ||

  	    arg.nr_errors[ATA_ECAT_UNK_DEV] > 6)

  		verdict |= ATA_EH_SPDN_SPEED_DOWN;

  	return verdict;

  }
  
  /**
   *	ata_eh_speed_down - record error and speed down if necessary
   *	@dev: Failed device

   *	@eflags: mask of ATA_EFLAG_* flags

   *	@err_mask: err_mask of the error
   *
   *	Record error and examine error history to determine whether
   *	adjusting transmission speed is necessary.  It also sets
   *	transmission limits appropriately if such adjustment is
   *	necessary.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   *
   *	RETURNS:

   *	Determined recovery action.

   */

  static unsigned int ata_eh_speed_down(struct ata_device *dev,
  				unsigned int eflags, unsigned int err_mask)

  {

  	struct ata_link *link = ata_dev_phys_link(dev);

  	int xfer_ok = 0;

  	unsigned int verdict;
  	unsigned int action = 0;
  
  	/* don't bother if Cat-0 error */

  	if (ata_eh_categorize_error(eflags, err_mask, &xfer_ok) == 0)

  		return 0;
  
  	/* record error and determine whether speed down is necessary */

  	ata_ering_record(&dev->ering, eflags, err_mask);

  	verdict = ata_eh_speed_down_verdict(dev);

  	/* turn off NCQ? */
  	if ((verdict & ATA_EH_SPDN_NCQ_OFF) &&
  	    (dev->flags & (ATA_DFLAG_PIO | ATA_DFLAG_NCQ |
  			   ATA_DFLAG_NCQ_OFF)) == ATA_DFLAG_NCQ) {
  		dev->flags |= ATA_DFLAG_NCQ_OFF;

  		ata_dev_warn(dev, "NCQ disabled due to excessive errors
  ");

  		goto done;
  	}

  	/* speed down? */
  	if (verdict & ATA_EH_SPDN_SPEED_DOWN) {
  		/* speed down SATA link speed if possible */

  		if (sata_down_spd_limit(link, 0) == 0) {

  			action |= ATA_EH_RESET;

  			goto done;
  		}

  		/* lower transfer mode */
  		if (dev->spdn_cnt < 2) {
  			static const int dma_dnxfer_sel[] =
  				{ ATA_DNXFER_DMA, ATA_DNXFER_40C };
  			static const int pio_dnxfer_sel[] =
  				{ ATA_DNXFER_PIO, ATA_DNXFER_FORCE_PIO0 };
  			int sel;
  
  			if (dev->xfer_shift != ATA_SHIFT_PIO)
  				sel = dma_dnxfer_sel[dev->spdn_cnt];
  			else
  				sel = pio_dnxfer_sel[dev->spdn_cnt];
  
  			dev->spdn_cnt++;
  
  			if (ata_down_xfermask_limit(dev, sel) == 0) {

  				action |= ATA_EH_RESET;

  				goto done;
  			}
  		}
  	}
  
  	/* Fall back to PIO?  Slowing down to PIO is meaningless for

  	 * SATA ATA devices.  Consider it only for PATA and SATAPI.

  	 */
  	if ((verdict & ATA_EH_SPDN_FALLBACK_TO_PIO) && (dev->spdn_cnt >= 2) &&

  	    (link->ap->cbl != ATA_CBL_SATA || dev->class == ATA_DEV_ATAPI) &&

  	    (dev->xfer_shift != ATA_SHIFT_PIO)) {
  		if (ata_down_xfermask_limit(dev, ATA_DNXFER_FORCE_PIO) == 0) {
  			dev->spdn_cnt = 0;

  			action |= ATA_EH_RESET;

  			goto done;
  		}
  	}

  	return 0;

   done:
  	/* device has been slowed down, blow error history */

  	if (!(verdict & ATA_EH_SPDN_KEEP_ERRORS))
  		ata_ering_clear(&dev->ering);

  	return action;

  }
  
  /**

   *	ata_eh_worth_retry - analyze error and decide whether to retry
   *	@qc: qc to possibly retry
   *
   *	Look at the cause of the error and decide if a retry
   * 	might be useful or not.  We don't want to retry media errors
   *	because the drive itself has probably already taken 10-30 seconds
   *	doing its own internal retries before reporting the failure.
   */
  static inline int ata_eh_worth_retry(struct ata_queued_cmd *qc)
  {

  	if (qc->err_mask & AC_ERR_MEDIA)

  		return 0;	/* don't retry media errors */
  	if (qc->flags & ATA_QCFLAG_IO)
  		return 1;	/* otherwise retry anything from fs stack */
  	if (qc->err_mask & AC_ERR_INVALID)
  		return 0;	/* don't retry these */
  	return qc->err_mask != AC_ERR_DEV;  /* retry if not dev error */
  }
  
  /**

   *	ata_eh_link_autopsy - analyze error and determine recovery action
   *	@link: host link to perform autopsy on

   *

   *	Analyze why @link failed and determine which recovery actions
   *	are needed.  This function also sets more detailed AC_ERR_*
   *	values and fills sense data for ATAPI CHECK SENSE.

   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   */

  static void ata_eh_link_autopsy(struct ata_link *link)

  {

  	struct ata_port *ap = link->ap;

  	struct ata_eh_context *ehc = &link->eh_context;

  	struct ata_device *dev;

  	unsigned int all_err_mask = 0, eflags = 0;
  	int tag;

  	u32 serror;
  	int rc;
  
  	DPRINTK("ENTER
  ");

  	if (ehc->i.flags & ATA_EHI_NO_AUTOPSY)
  		return;

  	/* obtain and analyze SError */

  	rc = sata_scr_read(link, SCR_ERROR, &serror);

  	if (rc == 0) {
  		ehc->i.serror |= serror;

  		ata_eh_analyze_serror(link);

  	} else if (rc != -EOPNOTSUPP) {

  		/* SError read failed, force reset and probing */

  		ehc->i.probe_mask |= ATA_ALL_DEVICES;

  		ehc->i.action |= ATA_EH_RESET;

  		ehc->i.err_mask |= AC_ERR_OTHER;
  	}

  	/* analyze NCQ failure */

  	ata_eh_analyze_ncq_error(link);

  	/* any real error trumps AC_ERR_OTHER */
  	if (ehc->i.err_mask & ~AC_ERR_OTHER)
  		ehc->i.err_mask &= ~AC_ERR_OTHER;
  
  	all_err_mask |= ehc->i.err_mask;
  
  	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
  		struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);

  		if (!(qc->flags & ATA_QCFLAG_FAILED) ||
  		    ata_dev_phys_link(qc->dev) != link)

  			continue;
  
  		/* inherit upper level err_mask */
  		qc->err_mask |= ehc->i.err_mask;

  		/* analyze TF */

  		ehc->i.action |= ata_eh_analyze_tf(qc, &qc->result_tf);

  
  		/* DEV errors are probably spurious in case of ATA_BUS error */
  		if (qc->err_mask & AC_ERR_ATA_BUS)
  			qc->err_mask &= ~(AC_ERR_DEV | AC_ERR_MEDIA |
  					  AC_ERR_INVALID);
  
  		/* any real error trumps unknown error */
  		if (qc->err_mask & ~AC_ERR_OTHER)
  			qc->err_mask &= ~AC_ERR_OTHER;
  
  		/* SENSE_VALID trumps dev/unknown error and revalidation */

  		if (qc->flags & ATA_QCFLAG_SENSE_VALID)

  			qc->err_mask &= ~(AC_ERR_DEV | AC_ERR_OTHER);

  		/* determine whether the command is worth retrying */