[libata] Improve timeout handling

On a timeout call a device specific handler early in the recovery so that
we can complete and process successful commands which timed out due to IRQ
loss or the like rather more elegantly.

[Revised to exclude the timeout handling on a few devices that inherit from
 SFF but are not SFF enough to use the default timeout handler]

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 45 insertions, 1 deletions

diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index 9a10cb055ac2..8332e97a9de3 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -65,6 +65,8 @@ const struct ata_port_operations ata_sff_port_ops = {
 	.sff_irq_on		= ata_sff_irq_on,
 	.sff_irq_clear		= ata_sff_irq_clear,
 
+	.lost_interrupt		= ata_sff_lost_interrupt,
+
 	.port_start		= ata_sff_port_start,
 };
 EXPORT_SYMBOL_GPL(ata_sff_port_ops);
@@ -1647,7 +1649,7 @@ EXPORT_SYMBOL_GPL(ata_sff_qc_fill_rtf);
  *	RETURNS:
  *	One if interrupt was handled, zero if not (shared irq).
  */
-inline unsigned int ata_sff_host_intr(struct ata_port *ap,
+unsigned int ata_sff_host_intr(struct ata_port *ap,
 				      struct ata_queued_cmd *qc)
 {
 	struct ata_eh_info *ehi = &ap->link.eh_info;
@@ -1776,6 +1778,48 @@ irqreturn_t ata_sff_interrupt(int irq, void *dev_instance)
 EXPORT_SYMBOL_GPL(ata_sff_interrupt);
 
 /**
+ *	ata_sff_lost_interrupt	-	Check for an apparent lost interrupt
+ *	@ap: port that appears to have timed out
+ *
+ *	Called from the libata error handlers when the core code suspects
+ *	an interrupt has been lost. If it has complete anything we can and
+ *	then return. Interface must support altstatus for this faster
+ *	recovery to occur.
+ *
+ *	Locking:
+ *	Caller holds host lock
+ */
+
+void ata_sff_lost_interrupt(struct ata_port *ap)
+{
+	u8 status;
+	struct ata_queued_cmd *qc;
+
+	/* Only one outstanding command per SFF channel */
+	qc = ata_qc_from_tag(ap, ap->link.active_tag);
+	/* Check we have a live one.. */
+	if (qc == NULL ||  !(qc->flags & ATA_QCFLAG_ACTIVE))
+		return;
+	/* We cannot lose an interrupt on a polled command */
+	if (qc->tf.flags & ATA_TFLAG_POLLING)
+		return;
+	/* See if the controller thinks it is still busy - if so the command
+	   isn't a lost IRQ but is still in progress */
+	status = ata_sff_altstatus(ap);
+	if (status & ATA_BUSY)
+		return;
+
+	/* There was a command running, we are no longer busy and we have
+	   no interrupt. */
+	ata_port_printk(ap, KERN_WARNING, "lost interrupt (Status 0x%x)\n",
+								status);
+	/* Run the host interrupt logic as if the interrupt had not been
+	   lost */
+	ata_sff_host_intr(ap, qc);
+}
+EXPORT_SYMBOL_GPL(ata_sff_lost_interrupt);
+
+/**
  *	ata_sff_freeze - Freeze SFF controller port
  *	@ap: port to freeze
  *