[SCSI] qla2xxx: Add support to dynamically enable/disable ZIO.

ISP23xx and ISP24xx chips have support for an adaptive
method of posting SCSI command completions for multiple SCSI
commands during a single system interrupt.

SCSI commands are placed on the system response queue
without interrupting the host until 1) a delay timer
expires; or 2) a SCSI command completes with an error.

As long as the host software (qla2xxx) services the response
queue for completions (this polling is done during
queuecommand()) within the 'delay timer' period, the
firmware will not generate system interrupt.

Signed-off-by: Andrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/scsi/qla2xxx/qla_iocb.c b/drivers/scsi/qla2xxx/qla_iocb.c
index 37f82e2cd7f..d7355627f11 100644
--- a/drivers/scsi/qla2xxx/qla_iocb.c
+++ b/drivers/scsi/qla2xxx/qla_iocb.c
@@ -440,6 +440,11 @@ qla2x00_start_scsi(srb_t *sp)
         WRT_REG_WORD(ISP_REQ_Q_IN(ha, reg), ha->req_ring_index);
         RD_REG_WORD_RELAXED(ISP_REQ_Q_IN(ha, reg));     /* PCI Posting. */
 
+        /* Manage unprocessed RIO/ZIO commands in response queue. */
+        if (ha->flags.process_response_queue &&
+            ha->response_ring_ptr->signature != RESPONSE_PROCESSED)
+                qla2x00_process_response_queue(ha);
+
         spin_unlock_irqrestore(&ha->hardware_lock, flags);
         return (QLA_SUCCESS);
 
@@ -877,6 +882,11 @@ qla24xx_start_scsi(srb_t *sp)
         WRT_REG_DWORD(&reg->req_q_in, ha->req_ring_index);
         RD_REG_DWORD_RELAXED(&reg->req_q_in);           /* PCI Posting. */
 
+        /* Manage unprocessed RIO/ZIO commands in response queue. */
+        if (ha->flags.process_response_queue &&
+            ha->response_ring_ptr->signature != RESPONSE_PROCESSED)
+                qla24xx_process_response_queue(ha);
+
         spin_unlock_irqrestore(&ha->hardware_lock, flags);
         return QLA_SUCCESS;