[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>
diff --git a/drivers/scsi/hpsa.h b/drivers/scsi/hpsa.h
index 7b28d54..48f7812 100644
--- a/drivers/scsi/hpsa.h
+++ b/drivers/scsi/hpsa.h
@@ -258,12 +258,12 @@
{
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.)