[PATCHSET 06/11] prep for hotplug support, take 2

[PATCHSET 06/11] prep for hotplug support, take 2

[Tejun Heo]

Bang-Ga.

This is part of patchset series described in [T].

This is the second take of prep-for-hotplug-support patchset.  Changes
from the last take[L] are

* dev->flags is used for warm plug and synchronized with host_set
  lock.  ata_dev_init() is updated to clear non-persistent part of
  dev->flags while holding host_set lock.

* ap->orig_sata_spd_limit renamed to ap->hw_sata_spd_limit.

* sata_phy_debounce() implemented.  This function will be called
  before performing EH resets to settle devices instead of blind
  delay.  sata_phy_debounce() is superset of the wait used in
  sata_phy_resume() and sata_phy_resume() is converted to use it.

* TF access is made optional.  All probing (including boot probing)
  will be done via hotplug and hotplug probing is implemented such
  that ->tf_read/write() isn't necessary, so now drivers like
  sata_sil24 don't have to fake TF access.  As ->check_[alt]status()
  was embedded too deep, ata_noop_check_status() is added instead of
  making those methods optional.  In the long term, those low level
  methods should be separated from highlevel ops somehow.

* ops->prereset() added.  This function is the counterpart of
  postreset() and called before a series of resets.  This is quite
  similar to ->probe_init() except that it's called for all resets.
  prereset() can determine things like whether it's prepping for boot
  probing or not, and which reset will be performed by testing
  ap->flags and ehi.

* Followup-softreset handling implemented.

* hotplug will completely replace ->probe_init/reset().

This patchset is against

  upstream (acc696d93dcf993dec123d69d599979e1456ffec)
  + [1] prep-for-new-EH patchset
  + [2] new-EH-framework patchset, take 3
  + [3] new-EH-implementation patchset, take 3
  + [4] merge-irq-pio patchset
  + [5] add-NCQ-support patchset, take 3

--
tejun

[T] http://article.gmane.org/gmane.linux.ide/9957
[L] http://article.gmane.org/gmane.linux.ide/9579
[1] http://article.gmane.org/gmane.linux.ide/9959
[2] http://article.gmane.org/gmane.linux.ide/9984
[3] http://article.gmane.org/gmane.linux.ide/9995
[4] http://article.gmane.org/gmane.linux.ide/10005
[5] http://article.gmane.org/gmane.linux.ide/10011

[PATCH 02/14] libata-hp-prep: implement ata_dev_init()

[Tejun Heo]

Move initialization of struct ata_device into ata_dev_init() in
preparation for hotplug.  This patch calls ata_dev_init() from
ata_host_init() and thus makes no functional difference.

---

 drivers/scsi/libata-core.c |   28 ++++++++++++++++++++++------
 1 files changed, 22 insertions(+), 6 deletions(-)

bf81344569d3ceb459fa55121a0d69d9ed52f10e
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 54240db..d307164 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -5108,6 +5108,27 @@ static void ata_host_remove(struct ata_p
 }
 
 /**
+ *	ata_dev_init - Initialize an ata_device structure
+ *	@dev: Device structure to initialize
+ *
+ *	Initialize @dev in preparation for probing.
+ *
+ *	LOCKING:
+ *	Inherited from caller.
+ */
+void ata_dev_init(struct ata_device *dev)
+{
+	struct ata_port *ap = dev->ap;
+
+	memset((void *)dev, 0, sizeof(*dev));
+	dev->devno = dev - ap->device;
+	dev->pio_mask = UINT_MAX;
+	dev->mwdma_mask = UINT_MAX;
+	dev->udma_mask = UINT_MAX;
+	ata_ering_init(&dev->ering, ATA_DEV_ERING_SIZE);
+}
+
+/**
  *	ata_host_init - Initialize an ata_port structure
  *	@ap: Structure to initialize
  *	@host: associated SCSI mid-layer structure
@@ -5121,7 +5142,6 @@ static void ata_host_remove(struct ata_p
  *	LOCKING:
  *	Inherited from caller.
  */
-
 static void ata_host_init(struct ata_port *ap, struct Scsi_Host *host,
 			  struct ata_host_set *host_set,
 			  const struct ata_probe_ent *ent, unsigned int port_no)
@@ -5163,11 +5183,7 @@ static void ata_host_init(struct ata_por
 	for (i = 0; i < ATA_MAX_DEVICES; i++) {
 		struct ata_device *dev = &ap->device[i];
 		dev->ap = ap;
-		dev->devno = i;
-		dev->pio_mask = UINT_MAX;
-		dev->mwdma_mask = UINT_MAX;
-		dev->udma_mask = UINT_MAX;
-		ata_ering_init(&dev->ering, ATA_DEV_ERING_SIZE);
+		ata_dev_init(dev);
 	}
 
 #ifdef ATA_IRQ_TRAP
-- 
1.2.4

[PATCH 03/14] libata-hp-prep: make some ata_device fields persistent

[Tejun Heo]

Lifetimes of some fields span over device plugging/unplugging.  This
patch moves such persistent fields to the top of ata_device and
separate them with ATA_DEVICE_CLEAR_OFFSET.  Fields above the offset
are initialized once during host initializatino while all other fields
are cleared before hotplugging.  Currently ->ap, devno and part of
flags are persistent.

Note that flags is partially cleared while holding host_set lock.
This is to synchronize with later warm plug implementation which will
record hotplug request in dev->flags.

---

 drivers/scsi/libata-core.c |   14 ++++++++++++--
 include/linux/libata.h     |    8 ++++++--
 2 files changed, 18 insertions(+), 4 deletions(-)

480d38b7f94a98fe9c9b33db932d94652cfed779
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index d307164..6accef3 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -5119,9 +5119,18 @@ static void ata_host_remove(struct ata_p
 void ata_dev_init(struct ata_device *dev)
 {
 	struct ata_port *ap = dev->ap;
+	unsigned long flags;
+
+	/* High bits of dev->flags are used to record warm plug
+	 * requests which occur asynchronously.  Synchronize using
+	 * host_set lock.
+	 */
+	spin_lock_irqsave(&ap->host_set->lock, flags);
+	dev->flags &= ~ATA_DFLAG_INIT_MASK;
+	spin_unlock_irqrestore(&ap->host_set->lock, flags);
 
-	memset((void *)dev, 0, sizeof(*dev));
-	dev->devno = dev - ap->device;
+	memset((void *)dev + ATA_DEVICE_CLEAR_OFFSET, 0,
+	       sizeof(*dev) - ATA_DEVICE_CLEAR_OFFSET);
 	dev->pio_mask = UINT_MAX;
 	dev->mwdma_mask = UINT_MAX;
 	dev->udma_mask = UINT_MAX;
@@ -5183,6 +5192,7 @@ static void ata_host_init(struct ata_por
 	for (i = 0; i < ATA_MAX_DEVICES; i++) {
 		struct ata_device *dev = &ap->device[i];
 		dev->ap = ap;
+		dev->devno = i;
 		ata_dev_init(dev);
 	}
 
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 1f6e48e..99a78cf 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -129,6 +129,7 @@ enum {
 	ATA_DFLAG_CFG_MASK	= (1 << 8) - 1,
 
 	ATA_DFLAG_PIO		= (1 << 8), /* device currently in PIO mode */
+	ATA_DFLAG_INIT_MASK	= (1 << 16) - 1,
 
 	ATA_DFLAG_DETACH	= (1 << 16),
 	ATA_DFLAG_DETACHED	= (1 << 17),
@@ -408,10 +409,11 @@ struct ata_ering {
 
 struct ata_device {
 	struct ata_port		*ap;
-	u64			n_sectors;	/* size of device, if ATA */
+	unsigned int		devno;		/* 0 or 1 */
 	unsigned long		flags;		/* ATA_DFLAG_xxx */
+	/* fields above n_sectors are not cleared across device init */
+	u64			n_sectors;	/* size of device, if ATA */
 	unsigned int		class;		/* ATA_DEV_xxx */
-	unsigned int		devno;		/* 0 or 1 */
 	u16			id[ATA_ID_WORDS]; /* IDENTIFY xxx DEVICE data */
 	u8			pio_mode;
 	u8			dma_mode;
@@ -436,6 +438,8 @@ struct ata_device {
 	DEFINE_ATA_ERING	(ering, ATA_DEV_ERING_SIZE);
 };
 
+#define ATA_DEVICE_CLEAR_OFFSET		offsetof(struct ata_device, n_sectors)
+
 struct ata_eh_info {
 	struct ata_device	*dev;		/* offending device */
 	u32			serror;		/* SError from LLDD */
-- 
1.2.4

[PATCH 04/14] libata-hp-prep: update ata_scsi_find_dev() and friends

[Tejun Heo]

Separate out ata_find_dev() and __ata_scsi_find_dev() from
ata_scsi_find_dev().  ata_find_dev() checks ATA_FLAG_SLAVE_POSS for
id==1 case, so all three functions return NULL if id==1 is specified
for !SLAVE_POSS port.  These will be used by later hotplug
implementation.

---

 drivers/scsi/libata-scsi.c |   40 +++++++++++++++++++++++++---------------
 1 files changed, 25 insertions(+), 15 deletions(-)

9ac5a3ff896cfe11b51d5e781f2b4e2137b10142
diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index 996058a..bb40309 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -52,8 +52,12 @@
 #define SECTOR_SIZE	512
 
 typedef unsigned int (*ata_xlat_func_t)(struct ata_queued_cmd *qc, const u8 *scsicmd);
-static struct ata_device *
-ata_scsi_find_dev(struct ata_port *ap, const struct scsi_device *scsidev);
+
+static struct ata_device * __ata_scsi_find_dev(struct ata_port *ap,
+					const struct scsi_device *scsidev);
+static struct ata_device * ata_scsi_find_dev(struct ata_port *ap,
+					    const struct scsi_device *scsidev);
+
 
 #define RW_RECOVERY_MPAGE 0x1
 #define RW_RECOVERY_MPAGE_LEN 12
@@ -2308,6 +2312,23 @@ static unsigned int atapi_xlat(struct at
 	return 0;
 }
 
+static struct ata_device * ata_find_dev(struct ata_port *ap, int id)
+{
+	if (likely(id == 0 || (id == 1 && ap->flags & ATA_FLAG_SLAVE_POSS)))
+		return &ap->device[id];
+	return NULL;
+}
+
+static struct ata_device * __ata_scsi_find_dev(struct ata_port *ap,
+					const struct scsi_device *scsidev)
+{
+	/* skip commands not addressed to targets we simulate */
+	if (unlikely(scsidev->channel || scsidev->lun))
+		return NULL;
+
+	return ata_find_dev(ap, scsidev->id);
+}
+
 /**
  *	ata_scsi_find_dev - lookup ata_device from scsi_cmnd
  *	@ap: ATA port to which the device is attached
@@ -2324,23 +2345,12 @@ static unsigned int atapi_xlat(struct at
  *	RETURNS:
  *	Associated ATA device, or %NULL if not found.
  */
-
 static struct ata_device *
 ata_scsi_find_dev(struct ata_port *ap, const struct scsi_device *scsidev)
 {
-	struct ata_device *dev;
-
-	/* skip commands not addressed to targets we simulate */
-	if (likely(scsidev->id < ATA_MAX_DEVICES))
-		dev = &ap->device[scsidev->id];
-	else
-		return NULL;
-
-	if (unlikely((scsidev->channel != 0) ||
-		     (scsidev->lun != 0)))
-		return NULL;
+	struct ata_device *dev = __ata_scsi_find_dev(ap, scsidev);
 
-	if (unlikely(!ata_dev_enabled(dev)))
+	if (unlikely(!dev || !ata_dev_enabled(dev)))
 		return NULL;
 
 	if (!atapi_enabled || (ap->flags & ATA_FLAG_NO_ATAPI)) {
-- 
1.2.4

[PATCH 01/14] libata-hp-prep: add flags and eh_info/context fields for hotplug

[Tejun Heo]

Add hotplug related flags and eh_info/context fields.

---

 include/linux/libata.h |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

d60dd05d2cfd4a63b7ce869694c3060d2aeab9d8
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 97e25a6..1f6e48e 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -130,6 +130,9 @@ enum {
 
 	ATA_DFLAG_PIO		= (1 << 8), /* device currently in PIO mode */
 
+	ATA_DFLAG_DETACH	= (1 << 16),
+	ATA_DFLAG_DETACHED	= (1 << 17),
+
 	ATA_DEV_UNKNOWN		= 0,	/* unknown device */
 	ATA_DEV_ATA		= 1,	/* ATA device */
 	ATA_DEV_ATA_UNSUP	= 2,	/* ATA device (unsupported) */
@@ -161,6 +164,9 @@ enum {
 	ATA_FLAG_EH_PENDING	= (1 << 16), /* EH pending */
 	ATA_FLAG_FROZEN		= (1 << 17), /* port is frozen */
 	ATA_FLAG_RECOVERED	= (1 << 18), /* recovery action performed */
+	ATA_FLAG_LOADING	= (1 << 19), /* boot/loading probe */
+	ATA_FLAG_UNLOADING	= (1 << 20), /* module is unloading */
+	ATA_FLAG_SCSI_HOTPLUG	= (1 << 21), /* SCSI hotplug scheduled */
 
 	ATA_FLAG_DISABLED	= (1 << 22), /* port is disabled, ignore it */
 	ATA_FLAG_SUSPENDED	= (1 << 23), /* port is suspended (power) */
@@ -435,6 +441,7 @@ struct ata_eh_info {
 	u32			serror;		/* SError from LLDD */
 	unsigned int		err_mask;	/* port-wide err_mask */
 	unsigned int		action;		/* ATA_EH_* action mask */
+	unsigned int		probe_mask;
 	char			desc[ATA_EH_DESC_LEN];
 	int			desc_len;
 };
@@ -442,7 +449,9 @@ struct ata_eh_info {
 struct ata_eh_context {
 	struct ata_eh_info	i;
 	int			tries[ATA_MAX_DEVICES];
+	unsigned int		classes[ATA_MAX_DEVICES];
 	unsigned int		flags;		/* ATA_EHC_* */
+	unsigned int		did_probe_mask;
 };
 
 struct ata_port {
-- 
1.2.4

[PATCH 12/14] libata-hp-prep: implement ata_noop_check_status()

[Tejun Heo]

As with ops->tf_read, ops->check_status() and ops->check_altstatus()
don't make sense for controllers without single TF image.  As
->check_status() and ->check_altstatus() are deeply integrated into
libata core layer, implement ata_noop_check_status() as a temporary
measure.  This function always returns ATA_DRDY without doing
anything.

In the long term, these IO ops should be made optional and removed
from top level ata_port_operations such that driver implementing
high-level behavior don't have to bother with these.

---

 drivers/scsi/libata-core.c |   19 +++++++++++++++++++
 include/linux/libata.h     |    1 +
 2 files changed, 20 insertions(+), 0 deletions(-)

f404e622e1961647f77ef0d4bf7869e1e1dec70c
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 6d86479..2500854 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -702,6 +702,24 @@ static u64 ata_id_n_sectors(const u16 *i
 }
 
 /**
+ *	ata_noop_check_status - Fake device status reg
+ *	@ap: target port
+ *
+ *	This function performs no actual function and always returns
+ *	ATA_DRDY.
+ *
+ *	May be used as the check_status/altstatus() entry in
+ *	ata_port_operations.
+ *
+ *	LOCKING:
+ *	caller.
+ */
+u8 ata_noop_check_status(struct ata_port *ap)
+{
+	return ATA_DRDY;
+}
+
+/**
  *	ata_noop_dev_select - Select device 0/1 on ATA bus
  *	@ap: ATA channel to manipulate
  *	@device: ATA device (numbered from zero) to select
@@ -5768,6 +5786,7 @@ EXPORT_SYMBOL_GPL(ata_qc_issue_prot);
 EXPORT_SYMBOL_GPL(ata_tf_load);
 EXPORT_SYMBOL_GPL(ata_tf_read);
 EXPORT_SYMBOL_GPL(ata_noop_dev_select);
+EXPORT_SYMBOL_GPL(ata_noop_check_status);
 EXPORT_SYMBOL_GPL(ata_std_dev_select);
 EXPORT_SYMBOL_GPL(ata_tf_to_fis);
 EXPORT_SYMBOL_GPL(ata_tf_from_fis);
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 5c843a8..ac8e58c 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -666,6 +666,7 @@ extern void ata_tf_load(struct ata_port 
 extern void ata_tf_read(struct ata_port *ap, struct ata_taskfile *tf);
 extern void ata_tf_to_fis(const struct ata_taskfile *tf, u8 *fis, u8 pmp);
 extern void ata_tf_from_fis(const u8 *fis, struct ata_taskfile *tf);
+extern u8 ata_noop_check_status(struct ata_port *ap);
 extern void ata_noop_dev_select (struct ata_port *ap, unsigned int device);
 extern void ata_std_dev_select (struct ata_port *ap, unsigned int device);
 extern u8 ata_check_status(struct ata_port *ap);
-- 
1.2.4

[PATCH 14/14] libata-hp-prep: implement followup softreset handling

[Tejun Heo]

In some cases, hardreset must be followed by SRST.

* some controllers can't classify with hardreset
* some controllers can't wait for !BSY after hardreset (LLDD should
  explicitly request followup softreset by returning -EAGAIN)
* (later) PM needs SRST w/ PMP==15 to operate after hardreset

To handle above cases, this patch implements follow-up softreset.
After a hardreset, ata_eh_reset() checks whether any of above
conditions are met and do a follow-up softreset if necessary.

---

 drivers/scsi/libata-eh.c |   58 +++++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 52 insertions(+), 6 deletions(-)

413da5b8b08f955db5665d06a497ab7170469363
diff --git a/drivers/scsi/libata-eh.c b/drivers/scsi/libata-eh.c
index ee046c1..9dfaa66 100644
--- a/drivers/scsi/libata-eh.c
+++ b/drivers/scsi/libata-eh.c
@@ -1284,16 +1284,28 @@ static void ata_eh_report(struct ata_por
 	}
 }
 
-static int ata_eh_reset(struct ata_port *ap,
+static int ata_eh_followup_srst_needed(int rc, int classify,
+				       const unsigned int *classes)
+{
+	if (rc == -EAGAIN)
+		return 1;
+	if (rc != 0)
+		return 0;
+	if (classify && classes[0] == ATA_DEV_UNKNOWN)
+		return 1;
+	return 0;
+}
+
+static int ata_eh_reset(struct ata_port *ap, 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 = &ap->eh_context;
-	unsigned int classes[ATA_MAX_DEVICES];
+	unsigned int *classes = ehc->classes;
 	int tries = ATA_EH_RESET_TRIES;
 	unsigned int action;
 	ata_reset_fn_t reset;
-	int i, rc;
+	int i, did_followup_srst, rc;
 
 	/* Determine which reset to use and record in ehc->i.action.
 	 * prereset() may examine it to determine what kind of
@@ -1339,10 +1351,44 @@ static int ata_eh_reset(struct ata_port 
 
 	rc = ata_do_reset(ap, reset, classes);
 
+	did_followup_srst = 0;
+	if (reset == hardreset &&
+	    ata_eh_followup_srst_needed(rc, classify, classes)) {
+		/* okay, let's do follow-up softreset */
+		did_followup_srst = 1;
+		reset = softreset;
+
+		if (!reset) {
+			ata_port_printk(ap, KERN_ERR,
+					"follow-up softreset required "
+					"but no softreset avaliable\n");
+			return -EINVAL;
+		}
+
+		ata_eh_about_to_do(ap, ATA_EH_RESET_MASK);
+		rc = ata_do_reset(ap, reset, classes);
+
+		if (rc == 0 && classify &&
+		    classes[0] == ATA_DEV_UNKNOWN) {
+			ata_port_printk(ap, KERN_ERR,
+					"classification failed\n");
+			return -EINVAL;
+		}
+	}
+
 	if (rc && --tries) {
+		const char *type;
+
+		if (reset == softreset) {
+			if (did_followup_srst)
+				type = "follow-up soft";
+			else
+				type = "soft";
+		} else
+			type = "hard";
+
 		ata_port_printk(ap, KERN_WARNING,
-				"%sreset failed, retrying in 5 secs\n",
-				reset == softreset ? "soft" : "hard");
+				"%sreset failed, retrying in 5 secs\n", type);
 		ssleep(5);
 
 		if (reset == hardreset)
@@ -1460,7 +1506,7 @@ static int ata_eh_recover(struct ata_por
 	if (ehc->i.action & ATA_EH_RESET_MASK) {
 		ata_eh_freeze_port(ap);
 
-		rc = ata_eh_reset(ap, prereset, softreset, hardreset,
+		rc = ata_eh_reset(ap, 0, prereset, softreset, hardreset,
 				  postreset);
 		if (rc) {
 			ata_port_printk(ap, KERN_ERR,
-- 
1.2.4

[PATCH 05/14] libata-hp-prep: use __ata_scsi_find_dev()

[Tejun Heo]

Convert direct sdev -> dev lookup to __ata_scsi_find_dev().

---

 drivers/scsi/libata-scsi.c |   16 ++++++----------
 1 files changed, 6 insertions(+), 10 deletions(-)

3a5723bc1fbb5f4869b6dd5598cbeed7cb58f1e2
diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index bb40309..0316bc1 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -399,7 +399,7 @@ void ata_dump_status(unsigned id, struct
 int ata_scsi_device_resume(struct scsi_device *sdev)
 {
 	struct ata_port *ap = ata_shost_to_port(sdev->host);
-	struct ata_device *dev = &ap->device[sdev->id];
+	struct ata_device *dev = __ata_scsi_find_dev(ap, sdev);
 
 	return ata_device_resume(dev);
 }
@@ -407,7 +407,7 @@ int ata_scsi_device_resume(struct scsi_d
 int ata_scsi_device_suspend(struct scsi_device *sdev, pm_message_t state)
 {
 	struct ata_port *ap = ata_shost_to_port(sdev->host);
-	struct ata_device *dev = &ap->device[sdev->id];
+	struct ata_device *dev = __ata_scsi_find_dev(ap, sdev);
 
 	return ata_device_suspend(dev, state);
 }
@@ -713,19 +713,15 @@ static void ata_scsi_dev_config(struct s
 
 int ata_scsi_slave_config(struct scsi_device *sdev)
 {
+	struct ata_port *ap = ata_shost_to_port(sdev->host);
+	struct ata_device *dev = __ata_scsi_find_dev(ap, sdev);
+
 	ata_scsi_sdev_config(sdev);
 
 	blk_queue_max_phys_segments(sdev->request_queue, LIBATA_MAX_PRD);
 
-	if (sdev->id < ATA_MAX_DEVICES) {
-		struct ata_port *ap;
-		struct ata_device *dev;
-
-		ap = ata_shost_to_port(sdev->host);
-		dev = &ap->device[sdev->id];
-
+	if (dev)
 		ata_scsi_dev_config(sdev, dev);
-	}
 
 	return 0;	/* scsi layer doesn't check return value, sigh */
 }
-- 
1.2.4

[PATCH 10/14] libata-hp-prep: implement sata_phy_debounce()

[Tejun Heo]

With hotplug, PHY always needs to be debounced before a reset as any
reset might find new devices.  Extract PHY waiting code from
sata_phy_resume() and extend it to include SStatus debouncing.  Note
that sata_phy_debounce() is superset of what used to be done inside
sata_phy_resume().

Two sets of debounce timings are defined and an argument is added to
sata_phy_resume() to select between the two.

---

 drivers/scsi/libata-core.c |  103 ++++++++++++++++++++++++++++++++++++++------
 include/linux/libata.h     |   13 ++++++
 2 files changed, 101 insertions(+), 15 deletions(-)

31e0810e495194fb383ea61ddd059f22449352b0
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 1861373..636f044 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -2417,10 +2417,83 @@ err_out:
 	DPRINTK("EXIT\n");
 }
 
-static int sata_phy_resume(struct ata_port *ap)
+/**
+ *	sata_phy_debounce - debounce SATA phy status
+ *	@ap: ATA port to debounce SATA phy status for
+ *	@interval_msec: polling interval in millisecs
+ *	@duration_msec: debounce duration in millisecs
+ *	@timeout_msec: timeout in millisecs
+ *
+ *	Make sure SStatus of @ap reaches stable state, determined by
+ *	holding the same value where DET is not 1 for @duration_msec
+ *	polled every @interval_msec, before @timeout_msec.  Timeout
+ *	constraints the beginning of the stable state.  Because, after
+ *	hot unplugging, DET gets stuck at 1 on some controllers, this
+ *	functions waits until timeout then returns 0 if DET is stable
+ *	at 1.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep)
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+int sata_phy_debounce(struct ata_port *ap, unsigned long interval_msec,
+		      unsigned long duration_msec, unsigned long timeout_msec)
+{
+	unsigned long duration = duration_msec * HZ / 1000;
+	unsigned long timeout = jiffies + timeout_msec * HZ / 1000;
+	unsigned long last_jiffies;
+	u32 last, cur;
+	int rc;
+
+	if ((rc = ata_scr_read(ap, SCR_STATUS, &cur)))
+		return rc;
+	cur &= 0xf;
+
+	last = cur;
+	last_jiffies = jiffies;
+
+	while (1) {
+		msleep(interval_msec);
+		if ((rc = ata_scr_read(ap, SCR_STATUS, &cur)))
+			return rc;
+		cur &= 0xf;
+
+		/* DET stable? */
+		if (cur == last) {
+			if (cur == 1 && time_before(jiffies, timeout))
+				continue;
+			if (time_after(jiffies, last_jiffies + duration))
+				return 0;
+			continue;
+		}
+
+		/* unstable, start over */
+		last = cur;
+		last_jiffies = jiffies;
+
+		/* check timeout */
+		if (time_after(jiffies, timeout))
+			return -EBUSY;
+	}
+}
+
+/**
+ *	sata_phy_resume - resume SATA phy
+ *	@ap: ATA port to resume SATA phy for
+ *
+ *	Resume SATA phy of @ap and debounce it.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep)
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+int sata_phy_resume(struct ata_port *ap, int quick)
 {
-	unsigned long timeout = jiffies + (HZ * 5);
-	u32 scontrol, sstatus;
+	u32 scontrol;
 	int rc;
 
 	if ((rc = ata_scr_read(ap, SCR_CONTROL, &scontrol)))
@@ -2431,16 +2504,14 @@ static int sata_phy_resume(struct ata_po
 	if ((rc = ata_scr_write(ap, SCR_CONTROL, scontrol)))
 		return rc;
 
-	/* Wait for phy to become ready, if necessary. */
-	do {
-		msleep(200);
-		if ((rc = ata_scr_read(ap, SCR_STATUS, &sstatus)))
-			return rc;
-		if ((sstatus & 0xf) != 1)
-			return 0;
-	} while (time_before(jiffies, timeout));
-
-	return -EBUSY;
+	if (quick)
+		return sata_phy_debounce(ap, ATA_DEBOUNCE_QUICK_INTERVAL,
+					 ATA_DEBOUNCE_QUICK_DURATION,
+					 ATA_DEBOUNCE_QUICK_TIMEOUT);
+	else
+		return sata_phy_debounce(ap, ATA_DEBOUNCE_INTERVAL,
+					 ATA_DEBOUNCE_DURATION,
+					 ATA_DEBOUNCE_TIMEOUT);
 }
 
 /**
@@ -2459,7 +2530,7 @@ static int sata_phy_resume(struct ata_po
 void ata_std_probeinit(struct ata_port *ap)
 {
 	/* resume link */
-	sata_phy_resume(ap);
+	sata_phy_resume(ap, 1);
 
 	/* wait for device */
 	if (ata_port_online(ap))
@@ -2575,7 +2646,7 @@ int sata_std_hardreset(struct ata_port *
 	msleep(1);
 
 	/* bring phy back */
-	sata_phy_resume(ap);
+	sata_phy_resume(ap, 0);
 
 	/* TODO: phy layer with polling, timeouts, etc. */
 	if (ata_port_offline(ap)) {
@@ -5722,6 +5793,8 @@ EXPORT_SYMBOL_GPL(ata_set_sata_spd);
 EXPORT_SYMBOL_GPL(sata_phy_reset);
 EXPORT_SYMBOL_GPL(__sata_phy_reset);
 EXPORT_SYMBOL_GPL(ata_bus_reset);
+EXPORT_SYMBOL_GPL(sata_phy_debounce);
+EXPORT_SYMBOL_GPL(sata_phy_resume);
 EXPORT_SYMBOL_GPL(ata_std_probeinit);
 EXPORT_SYMBOL_GPL(ata_std_softreset);
 EXPORT_SYMBOL_GPL(sata_std_hardreset);
diff --git a/include/linux/libata.h b/include/linux/libata.h
index f4a544e..5c843a8 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -255,6 +255,15 @@ enum {
 	ATA_PROBE_MAX_TRIES	= 3,
 	ATA_EH_RESET_TRIES	= 3,
 	ATA_EH_DEV_TRIES	= 3,
+
+	/* timing constants in millisecs */
+	ATA_DEBOUNCE_QUICK_INTERVAL	= 5,
+	ATA_DEBOUNCE_QUICK_DURATION	= 100,
+	ATA_DEBOUNCE_QUICK_TIMEOUT	= 5000,
+
+	ATA_DEBOUNCE_INTERVAL	= 10,
+	ATA_DEBOUNCE_DURATION	= 500,
+	ATA_DEBOUNCE_TIMEOUT	= 10000,
 };
 
 enum hsm_task_states {
@@ -600,6 +609,10 @@ extern void __sata_phy_reset(struct ata_
 extern void sata_phy_reset(struct ata_port *ap);
 extern void ata_bus_reset(struct ata_port *ap);
 extern int ata_set_sata_spd(struct ata_port *ap);
+extern int sata_phy_debounce(struct ata_port *ap, unsigned long interval_msec,
+			     unsigned long duration_msec,
+			     unsigned long timeout_msec);
+extern int sata_phy_resume(struct ata_port *ap, int quick);
 extern int ata_drive_probe_reset(struct ata_port *ap,
 			ata_probeinit_fn_t probeinit,
 			ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
-- 
1.2.4

[PATCH 13/14] libata-hp-prep: add prereset() method and implement ata_std_prereset()

[Tejun Heo]

With hotplug, every reset might be a probing reset and thus something
similar to probe_init() is needed.  prereset() method is called before
a series of resets to a port and is the counterpart of postreset().
prereset() can also short-circuit probing by returning -ENODEV.

ata_std_prereset() waits for !BSY iff it's boot probe and the port is
online.  The rationales are...

* after hotplugging, BSY clearance is not reliable
* libata can recover from bad resets
* there is no standard way to implement it - some controllers can't
  even do it.

With this behavior, there is a chance that SRST may be issued before
the device enters DI0: Device_idle state which may or may not result
in SRST failure.  However, SATA PM specification states that waiting
for !BSY before issuing SRST is not always possible and thus excludes
the step from device enumeration procedure.  So, all in all, this
should be safe.

If waiting for !BSY before hotplug reset is possible and desirable for
a certain controller, its LLDD is responsible for implementing it.

While at it, this patch unifies function typedef's such that they all
have named arguments.

---

 drivers/scsi/ahci.c         |    3 ++
 drivers/scsi/libata-bmdma.c |   11 ++++++---
 drivers/scsi/libata-core.c  |   42 +++++++++++++++++++++++++++++++++
 drivers/scsi/libata-eh.c    |   54 +++++++++++++++++++++++++++++++++++--------
 drivers/scsi/sata_sil24.c   |    3 ++
 include/linux/libata.h      |   15 +++++++-----
 6 files changed, 106 insertions(+), 22 deletions(-)

561686a7d075c317603fe6aed443895d7ce42c2c
diff --git a/drivers/scsi/ahci.c b/drivers/scsi/ahci.c
index 9f020cd..f7b550a 100644
--- a/drivers/scsi/ahci.c
+++ b/drivers/scsi/ahci.c
@@ -1017,7 +1017,8 @@ static void ahci_error_handler(struct at
 	}
 
 	/* perform recovery */
-	ata_do_eh(ap, ahci_softreset, ahci_hardreset, ahci_postreset);
+	ata_do_eh(ap, ata_std_prereset, ahci_softreset, ahci_hardreset,
+		  ahci_postreset);
 }
 
 static void ahci_post_internal_cmd(struct ata_queued_cmd *qc)
diff --git a/drivers/scsi/libata-bmdma.c b/drivers/scsi/libata-bmdma.c
index 741ddc4..db5a975 100644
--- a/drivers/scsi/libata-bmdma.c
+++ b/drivers/scsi/libata-bmdma.c
@@ -695,6 +695,7 @@ void ata_bmdma_thaw(struct ata_port *ap)
 /**
  *	ata_bmdma_drive_eh - Perform EH with given methods for BMDMA controller
  *	@ap: port to handle error for
+ *	@prereset: prereset method (can be NULL)
  *	@softreset: softreset method (can be NULL)
  *	@hardreset: hardreset method (can be NULL)
  *	@postreset: postreset method (can be NULL)
@@ -710,8 +711,9 @@ void ata_bmdma_thaw(struct ata_port *ap)
  *	LOCKING:
  *	Kernel thread context (may sleep)
  */
-void ata_bmdma_drive_eh(struct ata_port *ap, ata_reset_fn_t softreset,
-			ata_reset_fn_t hardreset, ata_postreset_fn_t postreset)
+void ata_bmdma_drive_eh(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_host_set *host_set = ap->host_set;
 	struct ata_eh_context *ehc = &ap->eh_context;
@@ -759,7 +761,7 @@ void ata_bmdma_drive_eh(struct ata_port 
 		ata_eh_thaw_port(ap);
 
 	/* PIO and DMA engines have been stopped, perform recovery */
-	ata_do_eh(ap, softreset, hardreset, postreset);
+	ata_do_eh(ap, prereset, softreset, hardreset, postreset);
 }
 
 /**
@@ -779,7 +781,8 @@ void ata_bmdma_error_handler(struct ata_
 	if (ata_scr_valid(ap))
 		hardreset = sata_std_hardreset;
 
-	ata_bmdma_drive_eh(ap, ata_std_softreset, hardreset, ata_std_postreset);
+	ata_bmdma_drive_eh(ap, ata_std_prereset, ata_std_softreset, hardreset,
+			   ata_std_postreset);
 }
 
 /**
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 2500854..7259646 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -2533,6 +2533,47 @@ int sata_phy_resume(struct ata_port *ap,
 }
 
 /**
+ *	ata_std_prereset - prepare for reset
+ *	@ap: ATA port to be reset
+ *
+ *	@ap is about to be reset.  Initialize it.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep)
+ *
+ *	RETURNS:
+ *	0 on success, -errno otherwise.
+ */
+int ata_std_prereset(struct ata_port *ap)
+{
+	int boot_probe = ap->flags & ATA_FLAG_LOADING;
+	int rc;
+
+	/* if we're about to do hardreset, don't bother */
+	if (ap->eh_context.i.action & ATA_EH_HARDRESET)
+		return 0;
+
+	/* resume port */
+	rc = sata_phy_resume(ap, boot_probe);
+	if (rc && rc != -EOPNOTSUPP) {
+		/* phy resume failed, whine but continue */
+		ata_port_printk(ap, KERN_WARNING, "failed to resume link "
+				"for reset (errno=%d)\n", rc);
+	}
+
+	/* Wait for !BSY iff boot probe is in progress and we don't
+	 * know that no device is attached.  The boot probe test is
+	 * necessary because hotplugging doesn't clear BSY in many
+	 * cases.  As we wait for !BSY after resets, this should be
+	 * safe.
+	 */
+	if (boot_probe && !ata_port_offline(ap))
+		ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);
+
+	return 0;
+}
+
+/**
  *	ata_std_probeinit - initialize probing
  *	@ap: port to be probed
  *
@@ -5817,6 +5858,7 @@ EXPORT_SYMBOL_GPL(ata_bus_reset);
 EXPORT_SYMBOL_GPL(sata_phy_debounce);
 EXPORT_SYMBOL_GPL(sata_phy_resume);
 EXPORT_SYMBOL_GPL(ata_std_probeinit);
+EXPORT_SYMBOL_GPL(ata_std_prereset);
 EXPORT_SYMBOL_GPL(ata_std_softreset);
 EXPORT_SYMBOL_GPL(sata_std_hardreset);
 EXPORT_SYMBOL_GPL(ata_std_postreset);
diff --git a/drivers/scsi/libata-eh.c b/drivers/scsi/libata-eh.c
index 740934b..ee046c1 100644
--- a/drivers/scsi/libata-eh.c
+++ b/drivers/scsi/libata-eh.c
@@ -1284,20 +1284,50 @@ static void ata_eh_report(struct ata_por
 	}
 }
 
-static int ata_eh_reset(struct ata_port *ap, ata_reset_fn_t softreset,
+static int ata_eh_reset(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_eh_context *ehc = &ap->eh_context;
 	unsigned int classes[ATA_MAX_DEVICES];
 	int tries = ATA_EH_RESET_TRIES;
+	unsigned int action;
 	ata_reset_fn_t reset;
-	int rc;
+	int i, rc;
 
+	/* Determine which reset to use and record in ehc->i.action.
+	 * prereset() may examine it to determine what kind of
+	 * preparation is needed.
+	 */
+	action = ehc->i.action;
+	ehc->i.action &= ~ATA_EH_RESET_MASK;
 	if (softreset && (!hardreset || (!ata_set_sata_spd_needed(ap) &&
-					 !(ehc->i.action & ATA_EH_HARDRESET))))
+					 !(action & ATA_EH_HARDRESET)))) {
+		ehc->i.action |= ATA_EH_SOFTRESET;
 		reset = softreset;
-	else
+	} else {
+		ehc->i.action |= ATA_EH_HARDRESET;
 		reset = hardreset;
+	}
+
+	if (prereset) {
+		rc = prereset(ap);
+
+		/* prereset can short-circuit resetting by returning
+		 * -ENODEV.
+		 */
+		if (rc == -ENODEV) {
+			for (i = 0; i < ATA_MAX_DEVICES; i++)
+				classes[i] = ATA_DEV_NONE;
+			return 0;
+		}
+
+		if (rc) {
+			ata_port_printk(ap, KERN_ERR,
+					"prereset failed (errno=%d)\n", rc);
+			return rc;
+		}
+	}
 
  retry:
 	ata_port_printk(ap, KERN_INFO, "%s resetting port\n",
@@ -1384,6 +1414,7 @@ static int ata_port_nr_enabled(struct at
 /**
  *	ata_eh_recover - recover host port after error
  *	@ap: host port to recover
+ *	@prereset: prereset method (can be NULL)
  *	@softreset: softreset method (can be NULL)
  *	@hardreset: hardreset method (can be NULL)
  *	@postreset: postreset method (can be NULL)
@@ -1400,8 +1431,8 @@ static int ata_port_nr_enabled(struct at
  *	RETURNS:
  *	0 on success, -errno on failure.
  */
-static int ata_eh_recover(struct ata_port *ap, ata_reset_fn_t softreset,
-			  ata_reset_fn_t hardreset,
+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_eh_context *ehc = &ap->eh_context;
@@ -1429,7 +1460,8 @@ static int ata_eh_recover(struct ata_por
 	if (ehc->i.action & ATA_EH_RESET_MASK) {
 		ata_eh_freeze_port(ap);
 
-		rc = ata_eh_reset(ap, softreset, hardreset, postreset);
+		rc = ata_eh_reset(ap, prereset, softreset, hardreset,
+				  postreset);
 		if (rc) {
 			ata_port_printk(ap, KERN_ERR,
 					"reset failed, giving up\n");
@@ -1546,6 +1578,7 @@ static void ata_eh_finish(struct ata_por
 /**
  *	ata_do_eh - do standard error handling
  *	@ap: host port to handle error for
+ *	@prereset: prereset method (can be NULL)
  *	@softreset: softreset method (can be NULL)
  *	@hardreset: hardreset method (can be NULL)
  *	@postreset: postreset method (can be NULL)
@@ -1555,11 +1588,12 @@ static void ata_eh_finish(struct ata_por
  *	LOCKING:
  *	Kernel thread context (may sleep).
  */
-void ata_do_eh(struct ata_port *ap, ata_reset_fn_t softreset,
-	       ata_reset_fn_t hardreset, ata_postreset_fn_t postreset)
+void ata_do_eh(struct ata_port *ap, ata_prereset_fn_t prereset,
+	       ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
+	       ata_postreset_fn_t postreset)
 {
 	ata_eh_autopsy(ap);
 	ata_eh_report(ap);
-	ata_eh_recover(ap, softreset, hardreset, postreset);
+	ata_eh_recover(ap, prereset, softreset, hardreset, postreset);
 	ata_eh_finish(ap);
 }
diff --git a/drivers/scsi/sata_sil24.c b/drivers/scsi/sata_sil24.c
index 202d34e..4747047 100644
--- a/drivers/scsi/sata_sil24.c
+++ b/drivers/scsi/sata_sil24.c
@@ -912,7 +912,8 @@ static void sil24_error_handler(struct a
 	}
 
 	/* perform recovery */
-	ata_do_eh(ap, sil24_softreset, sil24_hardreset, ata_std_postreset);
+	ata_do_eh(ap, ata_std_prereset, sil24_softreset, sil24_hardreset,
+		  ata_std_postreset);
 }
 
 static void sil24_post_internal_cmd(struct ata_queued_cmd *qc)
diff --git a/include/linux/libata.h b/include/linux/libata.h
index ac8e58c..9e06d82 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -296,9 +296,10 @@ struct ata_queued_cmd;
 
 /* typedefs */
 typedef void (*ata_qc_cb_t) (struct ata_queued_cmd *qc);
-typedef void (*ata_probeinit_fn_t)(struct ata_port *);
-typedef int (*ata_reset_fn_t)(struct ata_port *, unsigned int *);
-typedef void (*ata_postreset_fn_t)(struct ata_port *ap, unsigned int *);
+typedef void (*ata_probeinit_fn_t)(struct ata_port *ap);
+typedef int (*ata_prereset_fn_t)(struct ata_port *ap);
+typedef int (*ata_reset_fn_t)(struct ata_port *ap, unsigned int *classes);
+typedef void (*ata_postreset_fn_t)(struct ata_port *ap, unsigned int *classes);
 
 struct ata_ioports {
 	unsigned long		cmd_addr;
@@ -618,6 +619,7 @@ extern int ata_drive_probe_reset(struct 
 			ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
 			ata_postreset_fn_t postreset, unsigned int *classes);
 extern void ata_std_probeinit(struct ata_port *ap);
+extern int ata_std_prereset(struct ata_port *ap);
 extern int ata_std_softreset(struct ata_port *ap, unsigned int *classes);
 extern int sata_std_hardreset(struct ata_port *ap, unsigned int *class);
 extern void ata_std_postreset(struct ata_port *ap, unsigned int *classes);
@@ -696,7 +698,7 @@ extern u8   ata_bmdma_status(struct ata_
 extern void ata_bmdma_irq_clear(struct ata_port *ap);
 extern void ata_bmdma_freeze(struct ata_port *ap);
 extern void ata_bmdma_thaw(struct ata_port *ap);
-extern void ata_bmdma_drive_eh(struct ata_port *ap,
+extern void ata_bmdma_drive_eh(struct ata_port *ap, ata_prereset_fn_t prereset,
 			       ata_reset_fn_t softreset,
 			       ata_reset_fn_t hardreset,
 			       ata_postreset_fn_t postreset);
@@ -774,8 +776,9 @@ extern void ata_eh_thaw_port(struct ata_
 extern void ata_eh_qc_complete(struct ata_queued_cmd *qc);
 extern void ata_eh_qc_retry(struct ata_queued_cmd *qc);
 
-extern void ata_do_eh(struct ata_port *ap, ata_reset_fn_t softreset,
-		      ata_reset_fn_t hardreset, ata_postreset_fn_t postreset);
+extern void ata_do_eh(struct ata_port *ap, ata_prereset_fn_t prereset,
+		      ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
+		      ata_postreset_fn_t postreset);
 
 /*
  * printk helpers
-- 
1.2.4

[PATCH 11/14] libata-hp-prep: make ops->tf_read() optional

[Tejun Heo]

Not all controllers have single TF image and ops->tf_read() is
inappropriate for them.  Newly implemented hotplug probing will allow
drivers for such controllers to get rid of ops->tf_read() completely.
Make ops->tf_read() optional in core layer.

---

 drivers/scsi/libata-core.c |    8 +++++---
 drivers/scsi/libata-eh.c   |    3 ++-
 2 files changed, 7 insertions(+), 4 deletions(-)

164a958101ccf3f82b1af1be7dd77d991cd88d65
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 636f044..6d86479 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -4429,14 +4429,15 @@ void ata_qc_complete(struct ata_queued_c
 		if (unlikely(qc->flags & ATA_QCFLAG_FAILED)) {
 			if (!ata_tag_internal(qc->tag)) {
 				/* always fill result TF for failed qc */
-				ap->ops->tf_read(ap, &qc->result_tf);
+				if (ap->ops->tf_read)
+					ap->ops->tf_read(ap, &qc->result_tf);
 				ata_qc_schedule_eh(qc);
 				return;
 			}
 		}
 
 		/* read result TF if requested */
-		if (qc->flags & ATA_QCFLAG_RESULT_TF)
+		if (ap->ops->tf_read && qc->flags & ATA_QCFLAG_RESULT_TF)
 			ap->ops->tf_read(ap, &qc->result_tf);
 
 		__ata_qc_complete(qc);
@@ -4445,7 +4446,8 @@ void ata_qc_complete(struct ata_queued_c
 			return;
 
 		/* read result TF if failed or requested */
-		if (qc->err_mask || qc->flags & ATA_QCFLAG_RESULT_TF)
+		if (ap->ops->tf_read &&
+		    (qc->err_mask || qc->flags & ATA_QCFLAG_RESULT_TF))
 			ap->ops->tf_read(ap, &qc->result_tf);
 
 		__ata_qc_complete(qc);
diff --git a/drivers/scsi/libata-eh.c b/drivers/scsi/libata-eh.c
index b6268b5..740934b 100644
--- a/drivers/scsi/libata-eh.c
+++ b/drivers/scsi/libata-eh.c
@@ -811,7 +811,8 @@ static unsigned int atapi_eh_request_sen
 	memset(sense_buf, 0, SCSI_SENSE_BUFFERSIZE);
 
 	/* XXX: why tf_read here? */
-	ap->ops->tf_read(ap, &tf);
+	if (ap->ops->tf_read)
+		ap->ops->tf_read(ap, &tf);
 
 	/* fill these in, for the case where they are -not- overwritten */
 	sense_buf[0] = 0x70;
-- 
1.2.4

[PATCH 07/14] libata-hp-prep: store attached SCSI device

[Tejun Heo]

Add device persistent field dev->sdev and store the attached SCSI
device.  With hotplug, libata needs to know the attached SCSI device
to offline and detach it, but scsi_device_lookup() cannot be used
because libata will reuse SCSI ID numbers - dead but not gone devices
(due to zombie opens, etc...) interfere with the lookup.

dev->sdev doesn't hold reference to the SCSI device.  It's cleared
when the SCSI device goes away.

---

 drivers/scsi/libata-scsi.c |   14 ++++++++++----
 include/linux/libata.h     |    1 +
 2 files changed, 11 insertions(+), 4 deletions(-)

e04f46cf173e4b7f837ac75400eac20e2dd0d057
diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index 0316bc1..7827844 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -2738,17 +2738,23 @@ void ata_scsi_simulate(struct ata_device
 
 void ata_scsi_scan_host(struct ata_port *ap)
 {
-	struct ata_device *dev;
 	unsigned int i;
 
 	if (ap->flags & ATA_FLAG_DISABLED)
 		return;
 
 	for (i = 0; i < ATA_MAX_DEVICES; i++) {
-		dev = &ap->device[i];
+		struct ata_device *dev = &ap->device[i];
+		struct scsi_device *sdev;
 
-		if (ata_dev_enabled(dev))
-			scsi_scan_target(&ap->host->shost_gendev, 0, i, 0, 0);
+		if (!ata_dev_enabled(dev) || dev->sdev)
+			continue;
+
+		sdev = __scsi_add_device(ap->host, 0, i, 0, NULL);
+		if (!IS_ERR(sdev)) {
+			dev->sdev = sdev;
+			scsi_device_put(sdev);
+		}
 	}
 }
 
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 6ab988a..f4a544e 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -411,6 +411,7 @@ struct ata_device {
 	struct ata_port		*ap;
 	unsigned int		devno;		/* 0 or 1 */
 	unsigned long		flags;		/* ATA_DFLAG_xxx */
+	struct scsi_device	*sdev;		/* attached SCSI device */
 	/* fields above n_sectors are not cleared across device init */
 	u64			n_sectors;	/* size of device, if ATA */
 	unsigned int		class;		/* ATA_DEV_xxx */
-- 
1.2.4

[PATCH 06/14] libata-hp-prep: implement ap->hw_sata_spd_limit

[Tejun Heo]

Add ap->hw_sata_spd_limit and initialize it once during the boot
initialization (or driver load initialization).  ap->sata_spd_limit is
reset to ap->hw_sata_spd_limit on hotplug.  This prevents limits
introduced by earlier devices from affecting new devices.

---

 drivers/scsi/libata-core.c |   21 ++++++++++++---------
 include/linux/libata.h     |    1 +
 2 files changed, 13 insertions(+), 9 deletions(-)

658f9435c1ea00f1222bc0090b4bffe41111604f
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 6accef3..6da1005 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -2456,17 +2456,9 @@ static int sata_phy_resume(struct ata_po
  */
 void ata_std_probeinit(struct ata_port *ap)
 {
-	u32 scontrol;
-
 	/* resume link */
 	sata_phy_resume(ap);
 
-	/* init sata_spd_limit to the current value */
-	if (ata_scr_read(ap, SCR_CONTROL, &scontrol) == 0) {
-		int spd = (scontrol >> 4) & 0xf;
-		ap->sata_spd_limit &= (1 << spd) - 1;
-	}
-
 	/* wait for device */
 	if (ata_port_online(ap))
 		ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);
@@ -5121,6 +5113,9 @@ void ata_dev_init(struct ata_device *dev
 	struct ata_port *ap = dev->ap;
 	unsigned long flags;
 
+	/* SATA spd limit is bound to the first device */
+	ap->sata_spd_limit = ap->hw_sata_spd_limit;
+
 	/* High bits of dev->flags are used to record warm plug
 	 * requests which occur asynchronously.  Synchronize using
 	 * host_set lock.
@@ -5177,7 +5172,7 @@ static void ata_host_init(struct ata_por
 	ap->udma_mask = ent->udma_mask;
 	ap->flags |= ent->host_flags;
 	ap->ops = ent->port_ops;
-	ap->sata_spd_limit = UINT_MAX;
+	ap->hw_sata_spd_limit = UINT_MAX;
 	ap->active_tag = ATA_TAG_POISON;
 	ap->last_ctl = 0xFF;
 
@@ -5340,10 +5335,18 @@ int ata_device_add(const struct ata_prob
 	DPRINTK("probe begin\n");
 	for (i = 0; i < count; i++) {
 		struct ata_port *ap;
+		u32 scontrol;
 		int rc;
 
 		ap = host_set->ports[i];
 
+		/* init sata_spd_limit to the current value */
+		if (ata_scr_read(ap, SCR_CONTROL, &scontrol) == 0) {
+			int spd = (scontrol >> 4) & 0xf;
+			ap->hw_sata_spd_limit &= (1 << spd) - 1;
+		}
+		ap->sata_spd_limit = ap->hw_sata_spd_limit;
+
 		DPRINTK("ata%u: bus probe begin\n", ap->id);
 		rc = ata_bus_probe(ap);
 		DPRINTK("ata%u: bus probe end\n", ap->id);
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 99a78cf..6ab988a 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -480,6 +480,7 @@ struct ata_port {
 	unsigned int		mwdma_mask;
 	unsigned int		udma_mask;
 	unsigned int		cbl;	/* cable type; ATA_CBL_xxx */
+	unsigned int		hw_sata_spd_limit;
 	unsigned int		sata_spd_limit;	/* SATA PHY speed limit */
 
 	/* record runtime error info, protected by host_set lock */
-- 
1.2.4

[PATCH 08/14] libata-hp-prep: add ata_hotplug_wq

[Tejun Heo]

It's best to run ATA hotplug from EH but attaching SCSI devices needs
working EH.  ata_hotplug_wq is used to give SCSI hotplug operations a
separate context.

---

 drivers/scsi/libata-core.c |    9 +++++++++
 drivers/scsi/libata.h      |    1 +
 2 files changed, 10 insertions(+), 0 deletions(-)

60b0f9061e9ce6345e549a38d73f4759daae0339
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 6da1005..1f587aa 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -69,6 +69,8 @@ static void ata_dev_xfermask(struct ata_
 static unsigned int ata_unique_id = 1;
 static struct workqueue_struct *ata_wq;
 
+struct workqueue_struct *ata_hotplug_wq;
+
 int atapi_enabled = 1;
 module_param(atapi_enabled, int, 0444);
 MODULE_PARM_DESC(atapi_enabled, "Enable discovery of ATAPI devices (0=off, 1=on)");
@@ -5588,6 +5590,12 @@ static int __init ata_init(void)
 	if (!ata_wq)
 		return -ENOMEM;
 
+	ata_hotplug_wq = create_singlethread_workqueue("ata_hotplug");
+	if (!ata_hotplug_wq) {
+		destroy_workqueue(ata_wq);
+		return -ENOMEM;
+	}
+
 	printk(KERN_DEBUG "libata version " DRV_VERSION " loaded.\n");
 	return 0;
 }
@@ -5595,6 +5603,7 @@ static int __init ata_init(void)
 static void __exit ata_exit(void)
 {
 	destroy_workqueue(ata_wq);
+	destroy_workqueue(ata_hotplug_wq);
 }
 
 module_init(ata_init);
diff --git a/drivers/scsi/libata.h b/drivers/scsi/libata.h
index 134cb4d..ff50442 100644
--- a/drivers/scsi/libata.h
+++ b/drivers/scsi/libata.h
@@ -39,6 +39,7 @@ struct ata_scsi_args {
 };
 
 /* libata-core.c */
+extern struct workqueue_struct *ata_hotplug_wq;
 extern int atapi_enabled;
 extern int atapi_dmadir;
 extern int libata_fua;
-- 
1.2.4

[PATCH 09/14] libata-hp-prep: make probing related functions global

[Tejun Heo]

Hotplug will be implemented in libata-eh.c.  Make ata_dev_read_id()
and ata_dev_configure() global.

---

 drivers/scsi/libata-core.c |    6 +++---
 drivers/scsi/libata.h      |    3 +++
 2 files changed, 6 insertions(+), 3 deletions(-)

8d89cdee6d673f4e1915b3ec587dafec44456942
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 1f587aa..1861373 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -1164,8 +1164,8 @@ unsigned int ata_pio_need_iordy(const st
  *	RETURNS:
  *	0 on success, -errno otherwise.
  */
-static int ata_dev_read_id(struct ata_device *dev, unsigned int *p_class,
-			   int post_reset, u16 *id)
+int ata_dev_read_id(struct ata_device *dev, unsigned int *p_class,
+		    int post_reset, u16 *id)
 {
 	struct ata_port *ap = dev->ap;
 	unsigned int class = *p_class;
@@ -1289,7 +1289,7 @@ static void ata_dev_config_ncq(struct at
  *	RETURNS:
  *	0 on success, -errno otherwise
  */
-static int ata_dev_configure(struct ata_device *dev, int print_info)
+int ata_dev_configure(struct ata_device *dev, int print_info)
 {
 	struct ata_port *ap = dev->ap;
 	const u16 *id = dev->id;
diff --git a/drivers/scsi/libata.h b/drivers/scsi/libata.h
index ff50442..24dd534 100644
--- a/drivers/scsi/libata.h
+++ b/drivers/scsi/libata.h
@@ -50,6 +50,9 @@ extern void ata_port_flush_task(struct a
 extern unsigned ata_exec_internal(struct ata_device *dev,
 				  struct ata_taskfile *tf, const u8 *cdb,
 				  int dma_dir, void *buf, unsigned int buflen);
+extern int ata_dev_read_id(struct ata_device *dev, unsigned int *p_class,
+			   int post_reset, u16 *id);
+extern int ata_dev_configure(struct ata_device *dev, int print_info);
 extern int ata_down_sata_spd_limit(struct ata_port *ap);
 extern int ata_set_sata_spd_needed(struct ata_port *ap);
 extern int ata_down_xfermask_limit(struct ata_device *dev, int force_pio0);
-- 
1.2.4

Re: [PATCHSET 06/11] prep for hotplug support, take 2

[Jeff Garzik]

At this point, I run out of steam.

After the minor changes are committed, I could pull <= patchset #5 into 
#upstream immediately.

The upcoming ata_link patchset looks quite nice; that is definitely the 
direction I want to go.

I've already given hotplug plenty of thought (i.e. general design 
principles I like), so reviewing HP-related patchset should not take 
very long.  I'll need to refresh my PM-related design thoughts a bit 
before diving into that patchset, so that might take several days to get to.

	Jeff

Re: [PATCHSET 06/11] prep for hotplug support, take 2

[Tejun Heo]

Jeff Garzik wrote:
> At this point, I run out of steam.
> 
> After the minor changes are committed, I could pull <= patchset #5 into 
> #upstream immediately.

Great.  Once I get your responses and sorts out AHCI EH, I'll make new 
git branch you can pull from.  I can't wait to push those to #upstream. 
  Managing 120 stacked patches was a nightmare.  If I change something 
early in the series, even a simple/silly stuff, it causes a lot of 
rejects in later patches.

> The upcoming ata_link patchset looks quite nice; that is definitely the 
> direction I want to go.

Great.

> I've already given hotplug plenty of thought (i.e. general design 
> principles I like), so reviewing HP-related patchset should not take 
> very long.  I'll need to refresh my PM-related design thoughts a bit 
> before diving into that patchset, so that might take several days to get 
> to.

I'm still working on power applied together case because ahci is failing 
the first reset in a lot of cases.  Waiting for several secs before 
hotplug reset solved the problem for sata_sil and sata_sil24 but ahci's 
problem seems to be a different one - it doesn't seem to update TF for 
the first FIS after hotplug reset.  However, those changes are minor and 
wouldn't affect reviewing process, I think.

Thanks for reviewing and good night. :)

-- 
tejun