[PATCHSET 3/4] libata: prep for PMP support, take 5

[PATCHSET 3/4] libata: prep for PMP support, take 5

[Tejun Heo]

Hello, all.

This is the fifth take of libata-pmp-prep patchset.  This patchset
contains 12 patches implementing various stuff needed for PMP.

#01	: add PMP related constants
#02-04	: various small stuff
#05-06	: qc_defer mechanism implementation
#07-11	: link/device quirks and EH fast-fail path - things needed to
	  handle quirky PMP fan-out links / pseudo devices.
#12	: SATA SDB notify handler

This patchset hasn't changed from the last take[L] other than being
regenerated.

This patchset is against

  libata-dev#upstream (d79eb6de54f180dc83b488b20747f0097fde3dea)
  + [1] misc-updates patchset
  + [2] libata-link patchset

Thanks.

--
tejun

[L] http://thread.gmane.org/gmane.linux.ide/20115
[1] http://thread.gmane.org/gmane.linux.ide/20824
[2] http://thread.gmane.org/gmane.linux.ide/20842

[PATCH 02/11] libata-pmp-prep: add @new_class to ata_dev_revalidate()

[Tejun Heo]

Consider newly found class code while revalidating.  PMP resetting
always results in valid class code and issuing PMP commands to
ATA/ATAPI device isn't very attractive.  Add @new_class to
ata_dev_revalidate() and check class code for revalidation.

Signed-off-by: Tejun Heo <htejun@gmail.com>
---
 drivers/ata/libata-core.c |   15 +++++++++++++--
 drivers/ata/libata-eh.c   |    3 ++-
 drivers/ata/libata.h      |    3 ++-
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 19e831a..684996a 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -2766,7 +2766,7 @@ static int ata_dev_set_mode(struct ata_device *dev)
 	}
 
 	ehc->i.flags |= ATA_EHI_POST_SETMODE;
-	rc = ata_dev_revalidate(dev, 0);
+	rc = ata_dev_revalidate(dev, ATA_DEV_UNKNOWN, 0);
 	ehc->i.flags &= ~ATA_EHI_POST_SETMODE;
 	if (rc)
 		return rc;
@@ -3668,6 +3668,7 @@ int ata_dev_reread_id(struct ata_device *dev, unsigned int readid_flags)
 /**
  *	ata_dev_revalidate - Revalidate ATA device
  *	@dev: device to revalidate
+ *	@new_class: new class code
  *	@readid_flags: read ID flags
  *
  *	Re-read IDENTIFY page, make sure @dev is still attached to the
@@ -3679,7 +3680,8 @@ int ata_dev_reread_id(struct ata_device *dev, unsigned int readid_flags)
  *	RETURNS:
  *	0 on success, negative errno otherwise
  */
-int ata_dev_revalidate(struct ata_device *dev, unsigned int readid_flags)
+int ata_dev_revalidate(struct ata_device *dev, unsigned int new_class,
+		       unsigned int readid_flags)
 {
 	u64 n_sectors = dev->n_sectors;
 	int rc;
@@ -3687,6 +3689,15 @@ int ata_dev_revalidate(struct ata_device *dev, unsigned int readid_flags)
 	if (!ata_dev_enabled(dev))
 		return -ENODEV;
 
+	/* fail early if !ATA && !ATAPI to avoid issuing [P]IDENTIFY to PMP */
+	if (ata_class_enabled(new_class) &&
+	    new_class != ATA_DEV_ATA && new_class != ATA_DEV_ATAPI) {
+		ata_dev_printk(dev, KERN_INFO, "class mismatch %u != %u\n",
+			       dev->class, new_class);
+		rc = -ENODEV;
+		goto fail;
+	}
+
 	/* re-read ID */
 	rc = ata_dev_reread_id(dev, readid_flags);
 	if (rc)
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 2ddc2ed..b91f413 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -2031,7 +2031,8 @@ static int ata_eh_revalidate_and_attach(struct ata_link *link,
 			}
 
 			ata_eh_about_to_do(link, dev, ATA_EH_REVALIDATE);
-			rc = ata_dev_revalidate(dev, readid_flags);
+			rc = ata_dev_revalidate(dev, ehc->classes[dev->devno],
+						readid_flags);
 			if (rc)
 				goto err;
 
diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index 6d85ede..4153817 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -76,7 +76,8 @@ extern unsigned int ata_do_simple_cmd(struct ata_device *dev, u8 cmd);
 extern int ata_dev_read_id(struct ata_device *dev, unsigned int *p_class,
 			   unsigned int flags, u16 *id);
 extern int ata_dev_reread_id(struct ata_device *dev, unsigned int readid_flags);
-extern int ata_dev_revalidate(struct ata_device *dev, unsigned int readid_flags);
+extern int ata_dev_revalidate(struct ata_device *dev, unsigned int new_class,
+			      unsigned int readid_flags);
 extern int ata_dev_configure(struct ata_device *dev);
 extern int sata_down_spd_limit(struct ata_link *link);
 extern int sata_set_spd_needed(struct ata_link *link);
-- 
1.5.0.3

[PATCH 03/11] libata-pmp-prep: make a number of functions global to libata

[Tejun Heo]

Make a number of functions from libata-core.c and libata-eh.c global
to libata (drivers/ata/libata.h).  These will be used by PMP.

Signed-off-by: Tejun Heo <htejun@gmail.com>
---
 drivers/ata/libata-core.c |    4 ++--
 drivers/ata/libata-eh.c   |   31 +++++++++++++++----------------
 drivers/ata/libata.h      |   17 +++++++++++++++++
 3 files changed, 34 insertions(+), 18 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 684996a..22e508e 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -6063,7 +6063,7 @@ void ata_dev_init(struct ata_device *dev)
  *	LOCKING:
  *	Kernel thread context (may sleep)
  */
-static void ata_link_init(struct ata_port *ap, struct ata_link *link, int pmp)
+void ata_link_init(struct ata_port *ap, struct ata_link *link, int pmp)
 {
 	int i;
 
@@ -6098,7 +6098,7 @@ static void ata_link_init(struct ata_port *ap, struct ata_link *link, int pmp)
  *	RETURNS:
  *	0 on success, -errno on failure.
  */
-static int sata_link_init_spd(struct ata_link *link)
+int sata_link_init_spd(struct ata_link *link)
 {
 	u32 scontrol, spd;
 	int rc;
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index b91f413..0eab780 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -74,7 +74,6 @@ static const unsigned long ata_eh_reset_timeouts[] = {
 };
 
 static void __ata_port_freeze(struct ata_port *ap);
-static void ata_eh_finish(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);
@@ -948,7 +947,7 @@ void ata_eh_qc_retry(struct ata_queued_cmd *qc)
  *	LOCKING:
  *	None.
  */
-static void ata_eh_detach_dev(struct ata_device *dev)
+void ata_eh_detach_dev(struct ata_device *dev)
 {
 	struct ata_link *link = dev->link;
 	struct ata_port *ap = link->ap;
@@ -985,8 +984,8 @@ static void ata_eh_detach_dev(struct ata_device *dev)
  *	LOCKING:
  *	None.
  */
-static void ata_eh_about_to_do(struct ata_link *link, struct ata_device *dev,
-			       unsigned int action)
+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;
@@ -1028,8 +1027,8 @@ static void ata_eh_about_to_do(struct ata_link *link, struct ata_device *dev,
  *	LOCKING:
  *	None.
  */
-static void ata_eh_done(struct ata_link *link, struct ata_device *dev,
-			unsigned int action)
+void ata_eh_done(struct ata_link *link, struct ata_device *dev,
+		 unsigned int action)
 {
 	struct ata_eh_context *ehc = &link->eh_context;
 
@@ -1689,7 +1688,7 @@ static void ata_eh_link_autopsy(struct ata_link *link)
  *	LOCKING:
  *	Kernel thread context (may sleep).
  */
-static void ata_eh_autopsy(struct ata_port *ap)
+void ata_eh_autopsy(struct ata_port *ap)
 {
 	struct ata_link *link;
 
@@ -1794,7 +1793,7 @@ static void ata_eh_link_report(struct ata_link *link)
  *	LOCKING:
  *	None.
  */
-static void ata_eh_report(struct ata_port *ap)
+void ata_eh_report(struct ata_port *ap)
 {
 	struct ata_link *link;
 
@@ -1845,9 +1844,9 @@ static int ata_eh_followup_srst_needed(int rc, int classify,
 	return 0;
 }
 
-static int ata_eh_reset(struct ata_link *link, int classify,
-			ata_prereset_fn_t prereset, ata_reset_fn_t softreset,
-			ata_reset_fn_t hardreset, ata_postreset_fn_t postreset)
+int ata_eh_reset(struct ata_link *link, int classify,
+		 ata_prereset_fn_t prereset, ata_reset_fn_t softreset,
+		 ata_reset_fn_t hardreset, ata_postreset_fn_t postreset)
 {
 	struct ata_eh_context *ehc = &link->eh_context;
 	unsigned int *classes = ehc->classes;
@@ -2223,10 +2222,10 @@ static int ata_eh_handle_dev_fail(struct ata_device *dev, int err)
  *	RETURNS:
  *	0 on success, -errno on failure.
  */
-static int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
-			  ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
-			  ata_postreset_fn_t postreset,
-			  struct ata_link **r_failed_link)
+int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
+		   ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
+		   ata_postreset_fn_t postreset,
+		   struct ata_link **r_failed_link)
 {
 	struct ata_link *link;
 	struct ata_device *dev;
@@ -2372,7 +2371,7 @@ static int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
  *	LOCKING:
  *	None.
  */
-static void ata_eh_finish(struct ata_port *ap)
+void ata_eh_finish(struct ata_port *ap)
 {
 	int tag;
 
diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index 4153817..fe09aa8 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -93,6 +93,8 @@ extern void ata_dev_select(struct ata_port *ap, unsigned int device,
 extern void swap_buf_le16(u16 *buf, unsigned int buf_words);
 extern int ata_flush_cache(struct ata_device *dev);
 extern void ata_dev_init(struct ata_device *dev);
+extern void ata_link_init(struct ata_port *ap, struct ata_link *link, int pmp);
+extern int sata_link_init_spd(struct ata_link *link);
 extern int ata_task_ioctl(struct scsi_device *scsidev, void __user *arg);
 extern int ata_cmd_ioctl(struct scsi_device *scsidev, void __user *arg);
 extern struct ata_port *ata_port_alloc(struct ata_host *host);
@@ -154,6 +156,21 @@ extern void ata_scsi_error(struct Scsi_Host *host);
 extern void ata_port_wait_eh(struct ata_port *ap);
 extern void ata_eh_fastdrain_timerfn(unsigned long arg);
 extern void ata_qc_schedule_eh(struct ata_queued_cmd *qc);
+extern void ata_eh_detach_dev(struct ata_device *dev);
+extern void ata_eh_about_to_do(struct ata_link *link, struct ata_device *dev,
+			       unsigned int action);
+extern void ata_eh_done(struct ata_link *link, struct ata_device *dev,
+			unsigned int action);
+extern void ata_eh_autopsy(struct ata_port *ap);
+extern void ata_eh_report(struct ata_port *ap);
+extern int ata_eh_reset(struct ata_link *link, int classify,
+			ata_prereset_fn_t prereset, ata_reset_fn_t softreset,
+			ata_reset_fn_t hardreset, ata_postreset_fn_t postreset);
+extern int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
+			  ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
+			  ata_postreset_fn_t postreset,
+			  struct ata_link **r_failed_disk);
+extern void ata_eh_finish(struct ata_port *ap);
 
 /* libata-sff.c */
 extern u8 ata_irq_on(struct ata_port *ap);
-- 
1.5.0.3

[PATCH 01/11] libata-pmp-prep: add PMP related constants, fields, ops and update helpers

[Tejun Heo]

Add PMP related constants, fields and ops.  Also, update
ata_class_enabled/disabled() such that PMP classes are considered.

Signed-off-by: Tejun Heo <htejun@gmail.com>
---
 include/linux/libata.h |   31 +++++++++++++++++++++++++++----
 1 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/include/linux/libata.h b/include/linux/libata.h
index 06e1ead..ac9f5f5 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -154,7 +154,11 @@ enum {
 	ATA_DEV_ATA_UNSUP	= 2,	/* ATA device (unsupported) */
 	ATA_DEV_ATAPI		= 3,	/* ATAPI device */
 	ATA_DEV_ATAPI_UNSUP	= 4,	/* ATAPI device (unsupported) */
-	ATA_DEV_NONE		= 5,	/* no device */
+	ATA_DEV_PMP		= 5,	/* SATA port multiplier */
+	ATA_DEV_PMP_UNSUP	= 6,	/* SATA port multiplier (unsupported) */
+	ATA_DEV_SEMB		= 7,	/* SEMB */
+	ATA_DEV_SEMB_UNSUP	= 8,	/* SEMB (unsupported) */
+	ATA_DEV_NONE		= 9,	/* no device */
 
 	/* struct ata_link flags */
 	ATA_LFLAG_HRST_TO_RESUME = (1 << 0), /* hardreset to resume link */
@@ -179,6 +183,8 @@ enum {
 	ATA_FLAG_IGN_SIMPLEX	= (1 << 15), /* ignore SIMPLEX */
 	ATA_FLAG_NO_IORDY	= (1 << 16), /* controller lacks iordy */
 	ATA_FLAG_ACPI_SATA	= (1 << 17), /* need native SATA ACPI layout */
+	ATA_FLAG_PMP		= (1 << 18),
+	ATA_FLAG_SDB_NOTIFY	= (1 << 19),
 
 	/* The following flag belongs to ap->pflags but is kept in
 	 * ap->flags because it's referenced in many LLDs and will be
@@ -295,6 +301,10 @@ enum {
 	/* how hard are we gonna try to probe/recover devices */
 	ATA_PROBE_MAX_TRIES	= 3,
 	ATA_EH_DEV_TRIES	= 3,
+	ATA_EH_PMP_TRIES	= 5,
+	ATA_EH_PMP_LINK_TRIES	= 3,
+
+	SATA_PMP_SCR_TIMEOUT	= 250,
 
 	/* Horkage types. May be set by libata or controller on drives
 	   (some horkage may be drive/controller pair dependant */
@@ -446,7 +456,12 @@ struct ata_device {
 	/* n_sector is used as CLEAR_OFFSET, read comment above CLEAR_OFFSET */
 	u64			n_sectors;	/* size of device, if ATA */
 	unsigned int		class;		/* ATA_DEV_xxx */
-	u16			id[ATA_ID_WORDS]; /* IDENTIFY xxx DEVICE data */
+
+	union {
+		u16		id[ATA_ID_WORDS]; /* IDENTIFY xxx DEVICE data */
+		u32		gscr[SATA_PMP_GSCR_DWORDS]; /* PMP GSCR block */
+	};
+
 	u8			pio_mode;
 	u8			dma_mode;
 	u8			xfer_mode;
@@ -625,6 +640,12 @@ struct ata_port_operations {
 	void (*qc_prep) (struct ata_queued_cmd *qc);
 	unsigned int (*qc_issue) (struct ata_queued_cmd *qc);
 
+	/* port multiplier */
+	void (*pmp_attach) (struct ata_port *ap);
+	void (*pmp_detach) (struct ata_port *ap);
+	int (*pmp_read) (struct ata_device *dev, int pmp, int reg, u32 *r_val);
+	int (*pmp_write) (struct ata_device *dev, int pmp, int reg, u32 val);
+
 	/* Error handlers.  ->error_handler overrides ->eng_timeout and
 	 * indicates that new-style EH is in place.
 	 */
@@ -1014,12 +1035,14 @@ static inline unsigned int ata_tag_internal(unsigned int tag)
  */
 static inline unsigned int ata_class_enabled(unsigned int class)
 {
-	return class == ATA_DEV_ATA || class == ATA_DEV_ATAPI;
+	return class == ATA_DEV_ATA || class == ATA_DEV_ATAPI ||
+		class == ATA_DEV_PMP || class == ATA_DEV_SEMB;
 }
 
 static inline unsigned int ata_class_disabled(unsigned int class)
 {
-	return class == ATA_DEV_ATA_UNSUP || class == ATA_DEV_ATAPI_UNSUP;
+	return class == ATA_DEV_ATA_UNSUP || class == ATA_DEV_ATAPI_UNSUP ||
+		class == ATA_DEV_PMP_UNSUP || class == ATA_DEV_SEMB_UNSUP;
 }
 
 static inline unsigned int ata_class_absent(unsigned int class)
-- 
1.5.0.3

[PATCH 04/11] libata-pmp-prep: implement ops->qc_defer()

[Tejun Heo]

Controllers which support PMP have various restrictions on which
combinations of commands are allowed to what number of devices
concurrently.  This patch implements ops->qc_defer() which determines
whether a qc can be issued at the moment or should be deferred.

If the function returns ATA_DEFER_LINK, the qc will be deferred until
a qc completes on the link.  If ATA_DEFER_PORT, until a qc completes
on any link.  The defer conditions are advisory and in general
ATA_DEFER_LINK can be considered as lower priority deferring than
ATA_DEFER_PORT.

ops->qc_defer() replaces fixed ata_scmd_need_defer().  For standard
NCQ/non-NCQ exclusion, ata_std_qc_defer() is implemented.  ahci and
sata_sil24 are converted to use ata_std_qc_defer().

ops->qc_defer() is heavier than the original mechanism because full qc
is prepped before determining to defer it, but various information is
needed to determine defer conditinos and fully translating a qc is the
only way to supply such information in generic manner.

IMHO, this shouldn't cause any noticeable performance issues as

* for most cases deferring occurs rarely (except for NCQ-aware
  cmd-switching PMP)
* translation itself isn't that expensive
* once deferred the command won't be repeated until another command
  completes which usually is a very long time cpu-wise.

Signed-off-by: Tejun Heo <htejun@gmail.com>
---
 drivers/ata/ahci.c        |    2 +
 drivers/ata/libata-core.c |   31 ++++++++++++++++++++++
 drivers/ata/libata-scsi.c |   62 +++++++++++++++++++--------------------------
 drivers/ata/sata_nv.c     |    1 +
 drivers/ata/sata_sil24.c  |    1 +
 include/linux/libata.h    |    6 ++++
 6 files changed, 67 insertions(+), 36 deletions(-)

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 8c1cad9..805887e 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -270,6 +270,7 @@ static const struct ata_port_operations ahci_ops = {
 
 	.tf_read		= ahci_tf_read,
 
+	.qc_defer		= ata_std_qc_defer,
 	.qc_prep		= ahci_qc_prep,
 	.qc_issue		= ahci_qc_issue,
 
@@ -304,6 +305,7 @@ static const struct ata_port_operations ahci_vt8251_ops = {
 
 	.tf_read		= ahci_tf_read,
 
+	.qc_defer		= ata_std_qc_defer,
 	.qc_prep		= ahci_qc_prep,
 	.qc_issue		= ahci_qc_issue,
 
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 22e508e..48c5780 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4196,6 +4196,36 @@ int ata_check_atapi_dma(struct ata_queued_cmd *qc)
 }
 
 /**
+ *	ata_std_qc_defer - Check whether a qc needs to be deferred
+ *	@qc: ATA command in question
+ *
+ *	Non-NCQ commands cannot run with any other command, NCQ or
+ *	not.  As upper layer only knows the queue depth, we are
+ *	responsible for maintaining exclusion.  This function checks
+ *	whether a new command @qc can be issued.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host lock)
+ *
+ *	RETURNS:
+ *	ATA_DEFER_* if deferring is needed, 0 otherwise.
+ */
+int ata_std_qc_defer(struct ata_queued_cmd *qc)
+{
+	struct ata_link *link = qc->dev->link;
+
+	if (qc->tf.protocol == ATA_PROT_NCQ) {
+		if (!ata_tag_valid(link->active_tag))
+			return 0;
+	} else {
+		if (!ata_tag_valid(link->active_tag) && !link->sactive)
+			return 0;
+	}
+
+	return ATA_DEFER_LINK;
+}
+
+/**
  *	ata_qc_prep - Prepare taskfile for submission
  *	@qc: Metadata associated with taskfile to be prepared
  *
@@ -6966,6 +6996,7 @@ EXPORT_SYMBOL_GPL(ata_interrupt);
 EXPORT_SYMBOL_GPL(ata_do_set_mode);
 EXPORT_SYMBOL_GPL(ata_data_xfer);
 EXPORT_SYMBOL_GPL(ata_data_xfer_noirq);
+EXPORT_SYMBOL_GPL(ata_std_qc_defer);
 EXPORT_SYMBOL_GPL(ata_qc_prep);
 EXPORT_SYMBOL_GPL(ata_dumb_qc_prep);
 EXPORT_SYMBOL_GPL(ata_noop_qc_prep);
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index c3c9840..1a1c018 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -755,6 +755,13 @@ static void ata_scsi_sdev_config(struct scsi_device *sdev)
 {
 	sdev->use_10_for_rw = 1;
 	sdev->use_10_for_ms = 1;
+
+	/* Schedule policy is determined by ->qc_defer() callback and
+	 * it needs to see every deferred qc.  Set dev_blocked to 1 to
+	 * prevent SCSI midlayer from automatically deferring
+	 * requests.
+	 */
+	sdev->max_device_blocked = 1;
 }
 
 static void ata_scsi_dev_config(struct scsi_device *sdev,
@@ -1422,37 +1429,6 @@ static void ata_scsi_qc_complete(struct ata_queued_cmd *qc)
 }
 
 /**
- *	ata_scmd_need_defer - Check whether we need to defer scmd
- *	@dev: ATA device to which the command is addressed
- *	@is_io: Is the command IO (and thus possibly NCQ)?
- *
- *	NCQ and non-NCQ commands cannot run together.  As upper layer
- *	only knows the queue depth, we are responsible for maintaining
- *	exclusion.  This function checks whether a new command can be
- *	issued to @dev.
- *
- *	LOCKING:
- *	spin_lock_irqsave(host lock)
- *
- *	RETURNS:
- *	1 if deferring is needed, 0 otherwise.
- */
-static int ata_scmd_need_defer(struct ata_device *dev, int is_io)
-{
-	struct ata_link *link = dev->link;
-	int is_ncq = is_io && ata_ncq_enabled(dev);
-
-	if (is_ncq) {
-		if (!ata_tag_valid(link->active_tag))
-			return 0;
-	} else {
-		if (!ata_tag_valid(link->active_tag) && !link->sactive)
-			return 0;
-	}
-	return 1;
-}
-
-/**
  *	ata_scsi_translate - Translate then issue SCSI command to ATA device
  *	@dev: ATA device to which the command is addressed
  *	@cmd: SCSI command to execute
@@ -1483,14 +1459,12 @@ static int ata_scsi_translate(struct ata_device *dev, struct scsi_cmnd *cmd,
 			      void (*done)(struct scsi_cmnd *),
 			      ata_xlat_func_t xlat_func)
 {
+	struct ata_port *ap = dev->link->ap;
 	struct ata_queued_cmd *qc;
-	int is_io = xlat_func == ata_scsi_rw_xlat;
+	int rc;
 
 	VPRINTK("ENTER\n");
 
-	if (unlikely(ata_scmd_need_defer(dev, is_io)))
-		goto defer;
-
 	qc = ata_scsi_qc_new(dev, cmd, done);
 	if (!qc)
 		goto err_mem;
@@ -1518,6 +1492,11 @@ static int ata_scsi_translate(struct ata_device *dev, struct scsi_cmnd *cmd,
 	if (xlat_func(qc))
 		goto early_finish;
 
+	if (ap->ops->qc_defer) {
+		if ((rc = ap->ops->qc_defer(qc)))
+			goto defer;
+	}
+
 	/* select device, send command to hardware */
 	ata_qc_issue(qc);
 
@@ -1539,8 +1518,12 @@ err_mem:
 	return 0;
 
 defer:
+	ata_qc_free(qc);
 	DPRINTK("EXIT - defer\n");
-	return SCSI_MLQUEUE_DEVICE_BUSY;
+	if (rc == ATA_DEFER_LINK)
+		return SCSI_MLQUEUE_DEVICE_BUSY;
+	else
+		return SCSI_MLQUEUE_HOST_BUSY;
 }
 
 /**
@@ -2943,6 +2926,13 @@ int ata_scsi_add_hosts(struct ata_host *host, struct scsi_host_template *sht)
 		shost->max_channel = 1;
 		shost->max_cmd_len = 16;
 
+		/* Schedule policy is determined by ->qc_defer()
+		 * callback and it needs to see every deferred qc.
+		 * Set host_blocked to 1 to prevent SCSI midlayer from
+		 * automatically deferring requests.
+		 */
+		shost->max_host_blocked = 1;
+
 		rc = scsi_add_host(ap->scsi_host, ap->host->dev);
 		if (rc)
 			goto err_add;
diff --git a/drivers/ata/sata_nv.c b/drivers/ata/sata_nv.c
index 1f71946..262e291 100644
--- a/drivers/ata/sata_nv.c
+++ b/drivers/ata/sata_nv.c
@@ -430,6 +430,7 @@ static const struct ata_port_operations nv_adma_ops = {
 	.bmdma_start		= ata_bmdma_start,
 	.bmdma_stop		= ata_bmdma_stop,
 	.bmdma_status		= ata_bmdma_status,
+	.qc_defer		= ata_std_qc_defer,
 	.qc_prep		= nv_adma_qc_prep,
 	.qc_issue		= nv_adma_qc_issue,
 	.freeze			= nv_adma_freeze,
diff --git a/drivers/ata/sata_sil24.c b/drivers/ata/sata_sil24.c
index 8d89053..480ce87 100644
--- a/drivers/ata/sata_sil24.c
+++ b/drivers/ata/sata_sil24.c
@@ -394,6 +394,7 @@ static const struct ata_port_operations sil24_ops = {
 
 	.tf_read		= sil24_tf_read,
 
+	.qc_defer		= ata_std_qc_defer,
 	.qc_prep		= sil24_qc_prep,
 	.qc_issue		= sil24_qc_issue,
 
diff --git a/include/linux/libata.h b/include/linux/libata.h
index ac9f5f5..6c0628d 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -269,6 +269,10 @@ enum {
 	/* ering size */
 	ATA_ERING_SIZE		= 32,
 
+	/* return values for ->qc_defer */
+	ATA_DEFER_LINK		= 1,
+	ATA_DEFER_PORT		= 2,
+
 	/* desc_len for ata_eh_info and context */
 	ATA_EH_DESC_LEN		= 80,
 
@@ -637,6 +641,7 @@ struct ata_port_operations {
 
 	void (*data_xfer) (struct ata_device *, unsigned char *, unsigned int, int);
 
+	int (*qc_defer) (struct ata_queued_cmd *qc);
 	void (*qc_prep) (struct ata_queued_cmd *qc);
 	unsigned int (*qc_issue) (struct ata_queued_cmd *qc);
 
@@ -821,6 +826,7 @@ extern void ata_data_xfer(struct ata_device *adev, unsigned char *buf,
 			  unsigned int buflen, int write_data);
 extern void ata_data_xfer_noirq(struct ata_device *adev, unsigned char *buf,
 				unsigned int buflen, int write_data);
+extern int ata_std_qc_defer(struct ata_queued_cmd *qc);
 extern void ata_dumb_qc_prep(struct ata_queued_cmd *qc);
 extern void ata_qc_prep(struct ata_queued_cmd *qc);
 extern void ata_noop_qc_prep(struct ata_queued_cmd *qc);
-- 
1.5.0.3

[PATCH 05/11] libata-pmp-prep: implement qc_defer helpers

[Tejun Heo]

Implement ap->nr_active_links (the number of links with active qcs),
ap->excl_link (pointer to link which can be used by ->qc_defer and is
cleared when a qc with ATA_QCFLAG_CLEAR_EXCL completes), and
ata_link_active().

These can be used by ->qc_defer() to implement proper command
exclusion.  This set of helpers seem enough for both sil24 (ATAPI
exclusion needed) and cmd-switching PMP.

Signed-off-by: Tejun Heo <htejun@gmail.com>
---
 drivers/ata/libata-core.c |   22 ++++++++++++++++++++--
 drivers/ata/libata-eh.c   |    5 +++++
 include/linux/libata.h    |    8 ++++++++
 3 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 48c5780..76e0197 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -1352,6 +1352,7 @@ unsigned ata_exec_internal_sg(struct ata_device *dev,
 	struct ata_queued_cmd *qc;
 	unsigned int tag, preempted_tag;
 	u32 preempted_sactive, preempted_qc_active;
+	int preempted_nr_active_links;
 	DECLARE_COMPLETION_ONSTACK(wait);
 	unsigned long flags;
 	unsigned int err_mask;
@@ -1390,9 +1391,11 @@ unsigned ata_exec_internal_sg(struct ata_device *dev,
 	preempted_tag = link->active_tag;
 	preempted_sactive = link->sactive;
 	preempted_qc_active = ap->qc_active;
+	preempted_nr_active_links = ap->nr_active_links;
 	link->active_tag = ATA_TAG_POISON;
 	link->sactive = 0;
 	ap->qc_active = 0;
+	ap->nr_active_links = 0;
 
 	/* prepare & issue qc */
 	qc->tf = *tf;
@@ -1471,6 +1474,7 @@ unsigned ata_exec_internal_sg(struct ata_device *dev,
 	link->active_tag = preempted_tag;
 	link->sactive = preempted_sactive;
 	ap->qc_active = preempted_qc_active;
+	ap->nr_active_links = preempted_nr_active_links;
 
 	/* XXX - Some LLDDs (sata_mv) disable port on command failure.
 	 * Until those drivers are fixed, we detect the condition
@@ -5259,10 +5263,19 @@ void __ata_qc_complete(struct ata_queued_cmd *qc)
 		ata_sg_clean(qc);
 
 	/* command should be marked inactive atomically with qc completion */
-	if (qc->tf.protocol == ATA_PROT_NCQ)
+	if (qc->tf.protocol == ATA_PROT_NCQ) {
 		link->sactive &= ~(1 << qc->tag);
-	else
+		if (!link->sactive)
+			ap->nr_active_links--;
+	} else {
 		link->active_tag = ATA_TAG_POISON;
+		ap->nr_active_links--;
+	}
+
+	/* clear exclusive status */
+	if (unlikely(qc->flags & ATA_QCFLAG_CLEAR_EXCL &&
+		     ap->excl_link == link))
+		ap->excl_link = NULL;
 
 	/* atapi: mark qc as inactive to prevent the interrupt handler
 	 * from completing the command twice later, before the error handler
@@ -5441,9 +5454,14 @@ void ata_qc_issue(struct ata_queued_cmd *qc)
 
 	if (qc->tf.protocol == ATA_PROT_NCQ) {
 		WARN_ON(link->sactive & (1 << qc->tag));
+
+		if (!link->sactive)
+			ap->nr_active_links++;
 		link->sactive |= 1 << qc->tag;
 	} else {
 		WARN_ON(link->sactive);
+
+		ap->nr_active_links++;
 		link->active_tag = qc->tag;
 	}
 
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 0eab780..93f023c 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -381,6 +381,7 @@ void ata_scsi_error(struct Scsi_Host *host)
 
 		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);
 
@@ -2401,6 +2402,10 @@ void ata_eh_finish(struct ata_port *ap)
 			}
 		}
 	}
+
+	/* make sure nr_active_links is zero after EH */
+	WARN_ON(ap->nr_active_links);
+	ap->nr_active_links = 0;
 }
 
 /**
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 6c0628d..3b8ce64 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -215,6 +215,7 @@ enum {
 	ATA_QCFLAG_DMAMAP	= ATA_QCFLAG_SG | ATA_QCFLAG_SINGLE,
 	ATA_QCFLAG_IO		= (1 << 3), /* standard IO command */
 	ATA_QCFLAG_RESULT_TF	= (1 << 4), /* result TF requested */
+	ATA_QCFLAG_CLEAR_EXCL	= (1 << 5), /* clear excl_link on completion */
 
 	ATA_QCFLAG_FAILED	= (1 << 16), /* cmd failed and is owned by EH */
 	ATA_QCFLAG_SENSE_VALID	= (1 << 17), /* sense data valid */
@@ -576,11 +577,13 @@ struct ata_port {
 	struct ata_queued_cmd	qcmd[ATA_MAX_QUEUE];
 	unsigned long		qc_allocated;
 	unsigned int		qc_active;
+	int			nr_active_links; /* #links with active qcs */
 
 	struct ata_link		link;	/* host default link */
 
 	int			nr_pmp_links;	/* nr of available PMP links */
 	struct ata_link		*pmp_link;	/* array of PMP links */
+	struct ata_link		*excl_link;	/* for PMP qc exclusion */
 
 	struct ata_port_stats	stats;
 	struct ata_host		*host;
@@ -1086,6 +1089,11 @@ static inline int ata_link_max_devices(const struct ata_link *link)
 	return 1;
 }
 
+static inline int ata_link_active(struct ata_link *link)
+{
+	return ata_tag_valid(link->active_tag) || link->sactive;
+}
+
 static inline struct ata_link *ata_port_first_link(struct ata_port *ap)
 {
 	if (ap->nr_pmp_links)
-- 
1.5.0.3

[PATCH 07/11] libata-pmp-prep: implement ATA_LFLAG_NO_RETRY

[Tejun Heo]

Some PMP links are connected to internal pseudo devices which may come
and go depending on situation.  There's no reason to try hard to
recover them.  ATA_LFLAG_NO_RETRY tells EH to not retry if the device
attached to the link fails.

Signed-off-by: Tejun Heo <htejun@gmail.com>
---
 drivers/ata/libata-eh.c |    5 ++++-
 include/linux/libata.h  |    1 +
 2 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index e5f644e..b99e70b 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -2262,7 +2262,10 @@ int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
 		struct ata_eh_context *ehc = &link->eh_context;
 
 		ata_link_for_each_dev(dev, link) {
-			ehc->tries[dev->devno] = ATA_EH_DEV_TRIES;
+			if (link->flags & ATA_LFLAG_NO_RETRY)
+				ehc->tries[dev->devno] = 1;
+			else
+				ehc->tries[dev->devno] = ATA_EH_DEV_TRIES;
 
 			/* collect port action mask recorded in dev actions */
 			ehc->i.action |= ehc->i.dev_action[dev->devno] &
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 3d84c2b..787cebc 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -168,6 +168,7 @@ enum {
 	ATA_LFLAG_ASSUME_ATA	= (1 << 3), /* assume ATA class */
 	ATA_LFLAG_ASSUME_SEMB	= (1 << 4), /* assume SEMB class */
 	ATA_LFLAG_ASSUME_CLASS	= ATA_LFLAG_ASSUME_ATA | ATA_LFLAG_ASSUME_SEMB,
+	ATA_LFLAG_NO_RETRY	= (1 << 5), /* don't retry this link */
 
 	/* struct ata_port flags */
 	ATA_FLAG_SLAVE_POSS	= (1 << 0), /* host supports slave dev */
-- 
1.5.0.3

[PATCH 06/11] libata-pmp-prep: implement ATA_LFLAG_NO_SRST, ASSUME_ATA and ASSUME_SEMB

[Tejun Heo]

Some links on some PMPs locks up on SRST and/or report incorrect
device signature.  Implement ATA_LFLAG_NO_SRST, ASSUME_ATA and
ASSUME_SEMB to handle these quirky links.  NO_SRST makes EH avoid
SRST.  ASSUME_ATA and SEMB forces class code to ATA and SEMB_UNSUP
respectively.  Note that SEMB isn't currently supported yet so the
_UNSUP variant is used.

Signed-off-by: Tejun Heo <htejun@gmail.com>
---
 drivers/ata/libata-eh.c |   42 ++++++++++++++++++++++++++++++++----------
 include/linux/libata.h  |    4 ++++
 2 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 93f023c..e5f644e 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -1833,14 +1833,18 @@ static int ata_do_reset(struct ata_link *link, ata_reset_fn_t reset,
 	return 0;
 }
 
-static int ata_eh_followup_srst_needed(int rc, int classify,
+static int ata_eh_followup_srst_needed(struct ata_link *link,
+				       int rc, int classify,
 				       const unsigned int *classes)
 {
+	if (link->flags & ATA_LFLAG_NO_SRST)
+		return 0;
 	if (rc == -EAGAIN)
 		return 1;
 	if (rc != 0)
 		return 0;
-	if (classify && classes[0] == ATA_DEV_UNKNOWN)
+	if (classify && !(link->flags & ATA_LFLAG_ASSUME_CLASS) &&
+	    classes[0] == ATA_DEV_UNKNOWN)
 		return 1;
 	return 0;
 }
@@ -1867,7 +1871,8 @@ int ata_eh_reset(struct ata_link *link, int classify,
 	 */
 	action = ehc->i.action;
 	ehc->i.action &= ~ATA_EH_RESET_MASK;
-	if (softreset && (!hardreset || (!sata_set_spd_needed(link) &&
+	if (softreset && (!hardreset || (!(link->flags & ATA_LFLAG_NO_SRST) &&
+					 !sata_set_spd_needed(link) &&
 					 !(action & ATA_EH_HARDRESET))))
 		ehc->i.action |= ATA_EH_SOFTRESET;
 	else
@@ -1930,7 +1935,7 @@ int ata_eh_reset(struct ata_link *link, int classify,
 	rc = ata_do_reset(link, reset, classes, deadline);
 
 	if (reset == hardreset &&
-	    ata_eh_followup_srst_needed(rc, classify, classes)) {
+	    ata_eh_followup_srst_needed(link, rc, classify, classes)) {
 		/* okay, let's do follow-up softreset */
 		reset = softreset;
 
@@ -1945,8 +1950,8 @@ int ata_eh_reset(struct ata_link *link, int classify,
 		ata_eh_about_to_do(link, NULL, ATA_EH_RESET_MASK);
 		rc = ata_do_reset(link, reset, classes, deadline);
 
-		if (rc == 0 && classify &&
-		    classes[0] == ATA_DEV_UNKNOWN) {
+		if (rc == 0 && classify && classes[0] == ATA_DEV_UNKNOWN &&
+		    !(link->flags & ATA_LFLAG_ASSUME_CLASS)) {
 			ata_link_printk(link, KERN_ERR,
 					"classification failed\n");
 			rc = -EINVAL;
@@ -1954,6 +1959,10 @@ int ata_eh_reset(struct ata_link *link, int classify,
 		}
 	}
 
+	/* if we skipped follow-up srst, clear rc */
+	if (rc == -EAGAIN)
+		rc = 0;
+
 	if (rc && try < ARRAY_SIZE(ata_eh_reset_timeouts)) {
 		unsigned long now = jiffies;
 
@@ -1978,12 +1987,25 @@ int ata_eh_reset(struct ata_link *link, int classify,
 	if (rc == 0) {
 		u32 sstatus;
 
-		/* After the reset, the device state is PIO 0 and the
-		 * controller state is undefined.  Record the mode.
-		 */
-		ata_link_for_each_dev(dev, link)
+		ata_link_for_each_dev(dev, link) {
+			/* After the reset, the device state is PIO 0
+			 * and the controller state is undefined.
+			 * Record the mode.
+			 */
 			dev->pio_mode = XFER_PIO_0;
 
+			if (ata_link_offline(link))
+				continue;
+
+			/* apply class override and convert UNKNOWN to NONE */
+			if (link->flags & ATA_LFLAG_ASSUME_ATA)
+				classes[dev->devno] = ATA_DEV_ATA;
+			else if (link->flags & ATA_LFLAG_ASSUME_SEMB)
+				classes[dev->devno] = ATA_DEV_SEMB_UNSUP; /* not yet */
+			else if (classes[dev->devno] == ATA_DEV_UNKNOWN)
+				classes[dev->devno] = ATA_DEV_NONE;
+		}
+
 		/* record current link speed */
 		if (sata_scr_read(link, SCR_STATUS, &sstatus) == 0)
 			link->sata_spd = (sstatus >> 4) & 0xf;
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 3b8ce64..3d84c2b 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -164,6 +164,10 @@ enum {
 	ATA_LFLAG_HRST_TO_RESUME = (1 << 0), /* hardreset to resume link */
 	ATA_LFLAG_SKIP_D2H_BSY	= (1 << 1), /* can't wait for the first D2H
 					     * Register FIS clearing BSY */
+	ATA_LFLAG_NO_SRST	= (1 << 2), /* avoid softreset */
+	ATA_LFLAG_ASSUME_ATA	= (1 << 3), /* assume ATA class */
+	ATA_LFLAG_ASSUME_SEMB	= (1 << 4), /* assume SEMB class */
+	ATA_LFLAG_ASSUME_CLASS	= ATA_LFLAG_ASSUME_ATA | ATA_LFLAG_ASSUME_SEMB,
 
 	/* struct ata_port flags */
 	ATA_FLAG_SLAVE_POSS	= (1 << 0), /* host supports slave dev */
-- 
1.5.0.3

[PATCH 09/11] libata-pmp-prep: implement EH fast-fail path

[Tejun Heo]

If PMP itself becomes inaccessible while trying to link a downstream
link, spending time to recover the downstream link doesn't make any
sense.  Make EH skip retry and fail fast if -ERESTART is received.

Signed-off-by: Tejun Heo <htejun@gmail.com>
---
 drivers/ata/libata-eh.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index c250d6d..7bd8d06 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -1977,7 +1977,7 @@ int ata_eh_reset(struct ata_link *link, int classify,
 	if (rc == -EAGAIN)
 		rc = 0;
 
-	if (rc && try < ARRAY_SIZE(ata_eh_reset_timeouts)) {
+	if (rc && rc != -ERESTART && try < ARRAY_SIZE(ata_eh_reset_timeouts)) {
 		unsigned long now = jiffies;
 
 		if (time_before(now, deadline)) {
-- 
1.5.0.3

[PATCH 10/11] libata-pmp-prep: implement ATA_HORKAGE_SKIP_PM

[Tejun Heo]

Some pseudo devices fail PM commands unnecessarily aborting system
suspend.  Implement ATA_HORKAGE_SKIP_PM which makes libata skip PM
commands for these devices.

Signed-off-by: Tejun Heo <htejun@gmail.com>
---
 drivers/ata/libata-scsi.c |    7 +++++++
 include/linux/libata.h    |    1 +
 2 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 1a1c018..3b8693f 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -950,6 +950,13 @@ static unsigned int ata_scsi_start_stop_xlat(struct ata_queued_cmd *qc)
 		goto invalid_fld;       /* LOEJ bit set not supported */
 	if (((cdb[4] >> 4) & 0xf) != 0)
 		goto invalid_fld;       /* power conditions not supported */
+
+	if (qc->dev->horkage & ATA_HORKAGE_SKIP_PM) {
+		/* the device lacks PM support, finish without doing anything */
+		scmd->result = SAM_STAT_GOOD;
+		return 1;
+	}
+
 	if (cdb[4] & 0x1) {
 		tf->nsect = 1;	/* 1 sector, lba=0 */
 
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 717fdb5..4e37180 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -325,6 +325,7 @@ enum {
 	ATA_HORKAGE_NODMA	= (1 << 1),	/* DMA problems */
 	ATA_HORKAGE_NONCQ	= (1 << 2),	/* Don't use NCQ */
 	ATA_HORKAGE_MAX_SEC_128	= (1 << 3),	/* Limit max sects to 128 */
+	ATA_HORKAGE_SKIP_PM	= (1 << 4),	/* Skip PM operations */
 };
 
 enum hsm_task_states {
-- 
1.5.0.3

[PATCH 08/11] libata-pmp-prep: implement ATA_LFLAG_DISABLED

[Tejun Heo]

Implement ATA_LFLAG_DISABLED.  The flag indicates the link is disabled
due to EH recovery failure.  While a link is disabled, no EH action is
taken on the link and suspend/resume become noop too.

This will be used by PMP links to manage failed links.

Signed-off-by: Tejun Heo <htejun@gmail.com>
---
 drivers/ata/libata-eh.c |   30 +++++++++++++++++++++++++++++-
 include/linux/libata.h  |    3 +++
 2 files changed, 32 insertions(+), 1 deletions(-)

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index b99e70b..c250d6d 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -1241,6 +1241,7 @@ 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) {
 		err_mask |= AC_ERR_ATA_BUS;
@@ -1259,7 +1260,20 @@ static void ata_eh_analyze_serror(struct ata_link *link)
 		err_mask |= AC_ERR_SYSTEM;
 		action |= ATA_EH_HARDRESET;
 	}
-	if (serror & (SERR_PHYRDY_CHG | SERR_DEV_XCHG))
+
+	/* 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.
+	 */
+	hotplug_mask = 0;
+
+	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;
@@ -2154,6 +2168,10 @@ static int ata_eh_skip_recovery(struct ata_link *link)
 	struct ata_eh_context *ehc = &link->eh_context;
 	struct ata_device *dev;
 
+	/* skip disabled links */
+	if (link->flags & ATA_LFLAG_DISABLED)
+		return 1;
+
 	/* thaw frozen port, resume link and recover failed devices */
 	if ((link->ap->pflags & ATA_PFLAG_FROZEN) ||
 	    (ehc->i.flags & ATA_EHI_RESUME_LINK) || ata_link_nr_enabled(link))
@@ -2254,6 +2272,7 @@ int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
 	struct ata_device *dev;
 	int nr_failed_devs, nr_disabled_devs;
 	int reset, rc;
+	unsigned long flags;
 
 	DPRINTK("ENTER\n");
 
@@ -2261,6 +2280,15 @@ int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
 	ata_port_for_each_link(link, ap) {
 		struct ata_eh_context *ehc = &link->eh_context;
 
+		/* re-enable link? */
+		if (ehc->i.action & ATA_EH_ENABLE_LINK) {
+			ata_eh_about_to_do(link, NULL, ATA_EH_ENABLE_LINK);
+			spin_lock_irqsave(ap->lock, flags);
+			link->flags &= ~ATA_LFLAG_DISABLED;
+			spin_unlock_irqrestore(ap->lock, flags);
+			ata_eh_done(link, NULL, ATA_EH_ENABLE_LINK);
+		}
+
 		ata_link_for_each_dev(dev, link) {
 			if (link->flags & ATA_LFLAG_NO_RETRY)
 				ehc->tries[dev->devno] = 1;
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 787cebc..717fdb5 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -169,6 +169,7 @@ enum {
 	ATA_LFLAG_ASSUME_SEMB	= (1 << 4), /* assume SEMB class */
 	ATA_LFLAG_ASSUME_CLASS	= ATA_LFLAG_ASSUME_ATA | ATA_LFLAG_ASSUME_SEMB,
 	ATA_LFLAG_NO_RETRY	= (1 << 5), /* don't retry this link */
+	ATA_LFLAG_DISABLED	= (1 << 6), /* link is disabled */
 
 	/* struct ata_port flags */
 	ATA_FLAG_SLAVE_POSS	= (1 << 0), /* host supports slave dev */
@@ -286,6 +287,7 @@ enum {
 	ATA_EH_REVALIDATE	= (1 << 0),
 	ATA_EH_SOFTRESET	= (1 << 1),
 	ATA_EH_HARDRESET	= (1 << 2),
+	ATA_EH_ENABLE_LINK	= (1 << 3),
 
 	ATA_EH_RESET_MASK	= ATA_EH_SOFTRESET | ATA_EH_HARDRESET,
 	ATA_EH_PERDEV_MASK	= ATA_EH_REVALIDATE,
@@ -991,6 +993,7 @@ static inline void ata_ehi_hotplugged(struct ata_eh_info *ehi)
 {
 	ata_ehi_schedule_probe(ehi);
 	ehi->flags |= ATA_EHI_HOTPLUGGED;
+	ehi->action |= ATA_EH_ENABLE_LINK;
 	ehi->err_mask |= AC_ERR_ATA_BUS;
 }
 
-- 
1.5.0.3

[PATCH 11/11] libata-pmp-prep: implement sata_async_notification()

[Tejun Heo]

Implement SATA async notification handler sata_async_notification().
LLDs can call this function when it suspects SDB_NOTIFY has occurred.
This function will check SCR_NOTIFICATION if available and schedule
proper EH action.

Currently, only PMP notification is handled.  The function can be
easily extended to cover ATAPI notification later.

Signed-off-by: Tejun Heo <htejun@gmail.com>
---
 drivers/ata/libata-core.c |    1 +
 drivers/ata/libata-eh.c   |   49 +++++++++++++++++++++++++++++++++++++++++++++
 include/linux/libata.h    |    1 +
 3 files changed, 51 insertions(+), 0 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 76e0197..438e524 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -7099,6 +7099,7 @@ EXPORT_SYMBOL_GPL(ata_port_schedule_eh);
 EXPORT_SYMBOL_GPL(ata_link_abort);
 EXPORT_SYMBOL_GPL(ata_port_abort);
 EXPORT_SYMBOL_GPL(ata_port_freeze);
+EXPORT_SYMBOL_GPL(sata_async_notification);
 EXPORT_SYMBOL_GPL(ata_eh_freeze_port);
 EXPORT_SYMBOL_GPL(ata_eh_thaw_port);
 EXPORT_SYMBOL_GPL(ata_eh_qc_complete);
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 7bd8d06..3cfa860 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -838,6 +838,55 @@ int ata_port_freeze(struct ata_port *ap)
 }
 
 /**
+ *	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_SDB_NOTIFY))
+		return 0;
+
+	rc = sata_scr_read(&ap->link, SCR_NOTIFICATION, &sntf);
+	if (rc == 0) {
+		if (!sntf)
+			return 0;
+
+		/* clear it */
+		sata_scr_write(&ap->link, SCR_NOTIFICATION, sntf);
+
+		/* PMP is reporting that PHY status of some downstream
+		 * ports have changed.  Schedule EH.
+		 */
+		if (ap->nr_pmp_links && (sntf & (1 << SATA_PMP_CTRL_PORT))) {
+			ata_port_schedule_eh(ap);
+			return 1;
+		}
+	} else {
+		/* Dunno what's going on.  Schedule EH if PMP is
+		 * attached.  It might be reporting PHY status change.
+		 */
+		if (ap->nr_pmp_links) {
+			ata_port_schedule_eh(ap);
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+/**
  *	ata_eh_freeze_port - EH helper to freeze port
  *	@ap: ATA port to freeze
  *
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 4e37180..989744a 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -947,6 +947,7 @@ extern void ata_port_schedule_eh(struct ata_port *ap);
 extern int ata_link_abort(struct ata_link *link);
 extern int ata_port_abort(struct ata_port *ap);
 extern int ata_port_freeze(struct ata_port *ap);
+extern int sata_async_notification(struct ata_port *ap);
 
 extern void ata_eh_freeze_port(struct ata_port *ap);
 extern void ata_eh_thaw_port(struct ata_port *ap);
-- 
1.5.0.3