[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
  *