scsi: arcmsr: Add driver module parameter msi_enable

Add module parameter msi_enable so user has the option of disabling MSI
interrupts if there is a platform problem.
Signed-off-by: Ching Huang <ching2048@areca.com.tw>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/arcmsr/arcmsr_hba.c

@@ -75,6 +75,10 @@ MODULE_DESCRIPTION("Areca ARC11xx/12xx/16xx/188x SAS/SATA RAID Controller Driver
 MODULE_LICENSE("Dual BSD/GPL");
 MODULE_VERSION(ARCMSR_DRIVER_VERSION);
 
+static int msi_enable = 1;
+module_param(msi_enable, int, S_IRUGO);
+MODULE_PARM_DESC(msi_enable, "Enable MSI interrupt(0 ~ 1), msi_enable=1(enable), =0(disable)");
+
 static int host_can_queue = ARCMSR_DEFAULT_OUTSTANDING_CMD;
 module_param(host_can_queue, int, S_IRUGO);
 MODULE_PARM_DESC(host_can_queue, " adapter queue depth(32 ~ 1024), default is 128");
@@ -831,11 +835,17 @@ arcmsr_request_irq(struct pci_dev *pdev, struct AdapterControlBlock *acb)
 		pr_info("arcmsr%d: msi-x enabled\n", acb->host->host_no);
 		flags = 0;
 	} else {
-		nvec = pci_alloc_irq_vectors(pdev, 1, 1,
-				PCI_IRQ_MSI | PCI_IRQ_LEGACY);
+		if (msi_enable == 1) {
+			nvec = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI);
+			if (nvec == 1) {
+				dev_info(&pdev->dev, "msi enabled\n");
+				goto msi_int1;
+			}
+		}
+		nvec = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_LEGACY);
 		if (nvec < 1)
 			return FAILED;
-
+msi_int1:
 		flags = IRQF_SHARED;
 	}