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

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 tell EH to use different type of reset or skip reset by
modifying ehc->i.action.

This patch also implements ata_std_prereset().  Most controllers
should be able to use this function directly or with some wrapping.
After hotplug, different controllers need different actions to resume
the PHY and detect the newly attached device.  Controllers can be
categorized as follows.

* Controllers which can wait for the first D2H FIS after hotplug.
  Note that if the waiting is implemented by polling TF status, there
  needs to be a way to set BSY on PHY status change.  It can be
  implemented by hardware or with the help of the driver.

* Controllers which can wait for the first D2H FIS after sending
  COMRESET.  These controllers need to issue COMRESET to wait for the
  first FIS.  Note that the received D2H FIS could be the first D2H
  FIS after POR (power-on-reset) or D2H FIS in response to the
  COMRESET.  Some controllers use COMRESET as TF status
  synchronization point and clear TF automatically (sata_sil).

* Controllers which cannot wait for the first D2H FIS reliably.
  Blindly issuing SRST to spinning-up device often results in command
  issue failure or timeout, causing extended delay.  For these
  controllers, ata_std_prereset() explicitly waits ATA_SPINUP_WAIT
  (currently 8s) to give newly attached device time to spin up, then
  issues reset.  Note that failing to getting ready in ATA_SPINUP_WAIT
  is not critical.  libata will retry.  So, the timeout needs to be
  long enough to spin up most devices.

LLDDs can tell ata_std_prereset() which of above action is needed with
ATA_FLAG_HRST_TO_RESUME and ATA_FLAG_SKIP_D2H_BSY flags.  These flags
are PHY-specific property and will be moved to ata_link later.

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

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

1 files changed, 51 insertions, 9 deletions

diff --git a/drivers/scsi/libata-eh.c b/drivers/scsi/libata-eh.c
index 9173d8f2ce5..0e66f140e53 100644
--- a/drivers/scsi/libata-eh.c
+++ b/drivers/scsi/libata-eh.c
@@ -1318,20 +1318,58 @@ static void ata_eh_report(struct ata_port *ap)
 	}
 }
 
-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 i, rc;
 
+	/* Determine which reset to use and record in ehc->i.action.
+	 * prereset() may examine and modify it.
+	 */
+	action = ehc->i.action;
+	ehc->i.action &= ~ATA_EH_RESET_MASK;
 	if (softreset && (!hardreset || (!sata_set_spd_needed(ap) &&
-					 !(ehc->i.action & ATA_EH_HARDRESET))))
-		reset = softreset;
+					 !(action & ATA_EH_HARDRESET))))
+		ehc->i.action |= ATA_EH_SOFTRESET;
 	else
+		ehc->i.action |= ATA_EH_HARDRESET;
+
+	if (prereset) {
+		rc = prereset(ap);
+		if (rc) {
+			ata_port_printk(ap, KERN_ERR,
+					"prereset failed (errno=%d)\n", rc);
+			return rc;
+		}
+	}
+
+	/* prereset() might have modified ehc->i.action */
+	if (ehc->i.action & ATA_EH_HARDRESET)
 		reset = hardreset;
+	else if (ehc->i.action & ATA_EH_SOFTRESET)
+		reset = softreset;
+	else {
+		/* prereset told us not to reset, bang classes and return */
+		for (i = 0; i < ATA_MAX_DEVICES; i++)
+			classes[i] = ATA_DEV_NONE;
+		return 0;
+	}
+
+	/* did prereset() screw up?  if so, fix up to avoid oopsing */
+	if (!reset) {
+		ata_port_printk(ap, KERN_ERR, "BUG: prereset() requested "
+				"invalid reset type\n");
+		if (softreset)
+			reset = softreset;
+		else
+			reset = hardreset;
+	}
 
  retry:
 	ata_port_printk(ap, KERN_INFO, "%s resetting port\n",
@@ -1424,6 +1462,7 @@ static int ata_port_nr_enabled(struct ata_port *ap)
 /**
  *	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)
@@ -1440,8 +1479,8 @@ static int ata_port_nr_enabled(struct ata_port *ap)
  *	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;
@@ -1469,7 +1508,8 @@ static int ata_eh_recover(struct ata_port *ap, ata_reset_fn_t softreset,
 	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");
@@ -1586,6 +1626,7 @@ static void ata_eh_finish(struct ata_port *ap)
 /**
  *	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)
@@ -1595,11 +1636,12 @@ static void ata_eh_finish(struct ata_port *ap)
  *	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);
 }