2 files changed, 9 insertions, 1 deletions

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index e45b18ee04c3..f6b3e31f63cd 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1164,7 +1164,7 @@ static inline void ahci_gtf_filter_workaround(struct ata_host *host)
 #endif
 
 static int ahci_init_interrupts(struct pci_dev *pdev, unsigned int n_ports,
-                         struct ahci_host_priv *hpriv)
+                                struct ahci_host_priv *hpriv)
 {
         int nvec;
 
@@ -1189,6 +1189,13 @@ static int ahci_init_interrupts(struct pci_dev *pdev, unsigned int n_ports,
         else if (nvec < 0)
                 goto intx;
 
+        /* fallback to single MSI mode if the controller enforced MRSM mode */
+        if (readl(hpriv->mmio + HOST_CTL) & HOST_MRSM) {
+                pci_disable_msi(pdev);
+                printk(KERN_INFO "ahci: MRSM is on, fallback to single MSI\n");
+                goto single_msi;
+        }
+
         return nvec;
 
 single_msi:
diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
index 51af275b3388..b5eb886da226 100644
--- a/drivers/ata/ahci.h
+++ b/drivers/ata/ahci.h
@@ -94,6 +94,7 @@ enum {
         /* HOST_CTL bits */
         HOST_RESET              = (1 << 0),  /* reset controller; self-clear */
         HOST_IRQ_EN             = (1 << 1),  /* global IRQ enable */
+        HOST_MRSM               = (1 << 2),  /* MSI Revert to Single Message */
         HOST_AHCI_EN            = (1 << 31), /* AHCI enabled */
 
         /* HOST_CAP bits */