[PATCH] libata-dev: Let ata_hsm_move() work with both irq-pio and polling pio

Let ata_hsm_move() work with both irq-pio and polling pio codepath.

Changes:
- add a new parameter "in_wq" for polling pio
- add return value "poll_next" to tell polling pio task whether the HSM is finished
- merge code from ata_pio_first_block() to the HSM_ST_FIRST state.
- call ata_poll_qc_complete() if called from the workqueue

Signed-off-by: Albert Lee <albertcc@tw.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 094c790..33b39d3 100644 (file)
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -3805,11 +3805,36 @@ static void ata_pio_error(struct ata_port *ap)
        ata_poll_qc_complete(qc);
 }
 
-static void ata_hsm_move(struct ata_port *ap, struct ata_queued_cmd *qc,
-                        u8 status)
+/**
+ *     ata_hsm_move - move the HSM to the next state.
+ *     @ap: the target ata_port
+ *     @qc: qc on going
+ *     @status: current device status
+ *     @in_wq: 1 if called from workqueue, 0 otherwise
+ *
+ *     RETURNS:
+ *     1 when poll next status needed, 0 otherwise.
+ */
+
+static int ata_hsm_move(struct ata_port *ap, struct ata_queued_cmd *qc,
+                        u8 status, int in_wq)
 {
+       unsigned long flags = 0;
+       int poll_next;
+
        WARN_ON((qc->flags & ATA_QCFLAG_ACTIVE) == 0);
 
+       /* Make sure ata_qc_issue_prot() does not throw things
+        * like DMA polling into the workqueue. Notice that
+        * in_wq is not equivalent to (qc->tf.flags & ATA_TFLAG_POLLING).
+        */
+       WARN_ON(in_wq != ((qc->tf.flags & ATA_TFLAG_POLLING) ||
+                         (ap->hsm_task_state == HSM_ST_FIRST &&
+                          ((qc->tf.protocol == ATA_PROT_PIO &&
+                            (qc->tf.flags & ATA_TFLAG_WRITE)) ||
+                           (is_atapi_taskfile(&qc->tf) &&
+                            !(qc->dev->flags & ATA_DFLAG_CDB_INTR))))));
+
        /* check error */
        if (unlikely(status & (ATA_ERR | ATA_DF))) {
                qc->err_mask |= AC_ERR_DEV;
@@ -3819,6 +3844,14 @@ static void ata_hsm_move(struct ata_port *ap, struct ata_queued_cmd *qc,
 fsm_start:
        switch (ap->hsm_task_state) {
        case HSM_ST_FIRST:
+               /* Send first data block or PACKET CDB */
+
+               /* If polling, we will stay in the work queue after
+                * sending the data. Otherwise, interrupt handler
+                * takes over after sending the data.
+                */
+               poll_next = (qc->tf.flags & ATA_TFLAG_POLLING);
+
                /* check device status */
                if (unlikely((status & (ATA_BUSY | ATA_DRQ)) != ATA_DRQ)) {
                        /* Wrong status. Let EH handle this */
@@ -3827,8 +3860,36 @@ fsm_start:
                        goto fsm_start;
                }
 
-               atapi_send_cdb(ap, qc);
+               /* Send the CDB (atapi) or the first data block (ata pio out).
+                * During the state transition, interrupt handler shouldn't
+                * be invoked before the data transfer is complete and
+                * hsm_task_state is changed. Hence, the following locking.
+                */
+               if (in_wq)
+                       spin_lock_irqsave(&ap->host_set->lock, flags);
+
+               if (qc->tf.protocol == ATA_PROT_PIO) {
+                       /* PIO data out protocol.
+                        * send first data block.
+                        */
 
+                       /* ata_pio_sectors() might change the state
+                        * to HSM_ST_LAST. so, the state is changed here
+                        * before ata_pio_sectors().
+                        */
+                       ap->hsm_task_state = HSM_ST;
+                       ata_pio_sectors(qc);
+                       ata_altstatus(ap); /* flush */
+               } else
+                       /* send CDB */
+                       atapi_send_cdb(ap, qc);
+
+               if (in_wq)
+                       spin_unlock_irqrestore(&ap->host_set->lock, flags);
+
+               /* if polling, ata_pio_task() handles the rest.
+                * otherwise, interrupt handler takes over from here.
+                */
                break;
 
        case HSM_ST:
@@ -3868,6 +3929,7 @@ fsm_start:
                }
 
                ata_altstatus(ap); /* flush */
+               poll_next = 1;
                break;
 
        case HSM_ST_LAST:
@@ -3886,7 +3948,12 @@ fsm_start:
                ap->hsm_task_state = HSM_ST_IDLE;
 
                /* complete taskfile transaction */
-               ata_qc_complete(qc);
+               if (in_wq)
+                       ata_poll_qc_complete(qc);
+               else
+                       ata_qc_complete(qc);
+
+               poll_next = 0;
                break;
 
        case HSM_ST_ERR:
@@ -3900,12 +3967,20 @@ fsm_start:
                WARN_ON(qc->err_mask == 0);
 
                ap->hsm_task_state = HSM_ST_IDLE;
-               ata_qc_complete(qc);
+
+               if (in_wq)
+                       ata_poll_qc_complete(qc);
+               else
+                       ata_qc_complete(qc);
+
+               poll_next = 0;
                break;
        default:
+               poll_next = 0;
                BUG();
        }
 
+       return poll_next;
 }
 
 static void ata_pio_task(void *_data)
@@ -4423,7 +4498,7 @@ inline unsigned int ata_host_intr (struct ata_port *ap,
        /* ack bmdma irq events */
        ap->ops->irq_clear(ap);
 
-       ata_hsm_move(ap, qc, status);
+       ata_hsm_move(ap, qc, status, 0);
        return 1;       /* irq handled */
 
 idle_irq: