[SCSI] megaraid_sas: add readl to force PCI posting flush

MegaRAID SAS Driver get unexpected Interrupt.  Add the dummy readl to
force PCI flush will fix this issue.

Signed-off-by: Bo Yang <bo.yang@lsi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Stable Tree <stable@kernel.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/scsi/megaraid/megaraid_sas.c b/drivers/scsi/megaraid/megaraid_sas.c
index fc7ac158476..d7b99843ca3 100644
--- a/drivers/scsi/megaraid/megaraid_sas.c
+++ b/drivers/scsi/megaraid/megaraid_sas.c
@@ -198,6 +198,9 @@ megasas_clear_intr_xscale(struct megasas_register_set __iomem * regs)
          */
         writel(status, &regs->outbound_intr_status);
 
+        /* Dummy readl to force pci flush */
+        readl(&regs->outbound_intr_status);
+
         return 0;
 }
 
@@ -293,6 +296,9 @@ megasas_clear_intr_ppc(struct megasas_register_set __iomem * regs)
          */
         writel(status, &regs->outbound_doorbell_clear);
 
+        /* Dummy readl to force pci flush */
+        readl(&regs->outbound_doorbell_clear);
+
         return 0;
 }
 /**