[SCSI] hpsa: do not read from controller unnecessarily in completion code

MSI/MSI-X interrupts can't race the DMA completion they are communicating
so no need to read from controller to flush the DMA to the host if
MSI or MSI-X interrupts are being used.

Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/drivers/scsi/hpsa.h b/drivers/scsi/hpsa.h
index 7b28d54fa878..48f78123d1e6 100644
--- a/drivers/scsi/hpsa.h
+++ b/drivers/scsi/hpsa.h
@@ -258,12 +258,12 @@ static unsigned long SA5_performant_completed(struct ctlr_info *h)
 {
         unsigned long register_value = FIFO_EMPTY;
 
-        /* flush the controller write of the reply queue by reading
-         * outbound doorbell status register.
-         */
-        register_value = readl(h->vaddr + SA5_OUTDB_STATUS);
         /* msi auto clears the interrupt pending bit. */
         if (!(h->msi_vector || h->msix_vector)) {
+                /* flush the controller write of the reply queue by reading
+                 * outbound doorbell status register.
+                 */
+                register_value = readl(h->vaddr + SA5_OUTDB_STATUS);
                 writel(SA5_OUTDB_CLEAR_PERF_BIT, h->vaddr + SA5_OUTDB_CLEAR);
                 /* Do a read in order to flush the write to the controller
                  * (as per spec.)