[PATCH] megaraid_sas: enable message-signaled interrupts

[Clemens Ladisch <clemens@ladisch.de>]

To avoid sharing interrupts, enable message-signaled interrupts, if
possible.

Tested with LSI 9260-8i/8e, where sharing the interrupt with the nvidia
driver would reduce the RAID performance.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Tested-by: Bert dd <bert.ddecker@gmail.com>
---
 drivers/scsi/megaraid/megaraid_sas.c |   17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

--- a/drivers/scsi/megaraid/megaraid_sas.c
+++ b/drivers/scsi/megaraid/megaraid_sas.c
@@ -3169,10 +3169,14 @@ megasas_probe_one(struct pci_dev *pdev,
 	if (megasas_init_mfi(instance))
 		goto fail_init_mfi;
 
+	pci_enable_msi(pdev);
+
 	/*
 	 * Register IRQ
 	 */
-	if (request_irq(pdev->irq, megasas_isr, IRQF_SHARED, "megasas", instance)) {
+	if (request_irq(pdev->irq, megasas_isr,
+		pci_dev_msi_enabled(pdev) ? 0 : IRQF_SHARED,
+		"megasas", instance)) {
 		printk(KERN_DEBUG "megasas: Failed to register IRQ\n");
 		goto fail_irq;
 	}
@@ -3222,6 +3226,8 @@ megasas_probe_one(struct pci_dev *pdev,
 	megasas_release_mfi(instance);
 
       fail_irq:
+	pci_disable_msi(pdev);
+
       fail_init_mfi:
       fail_alloc_dma_buf:
 	if (instance->evt_detail)
@@ -3354,6 +3360,7 @@ megasas_suspend(struct pci_dev *pdev, pm
 	pci_set_drvdata(instance->pdev, instance);
 	instance->instancet->disable_intr(instance->reg_set);
 	free_irq(instance->pdev->irq, instance);
+	pci_disable_msi(pdev);
 
 	pci_save_state(pdev);
 	pci_disable_device(pdev);
@@ -3416,10 +3423,13 @@ megasas_resume(struct pci_dev *pdev)
 	tasklet_init(&instance->isr_tasklet, megasas_complete_cmd_dpc,
 			(unsigned long)instance);
 
+	pci_enable_msi(pdev);
+
 	/*
 	 * Register IRQ
 	 */
-	if (request_irq(pdev->irq, megasas_isr, IRQF_SHARED,
+	if (request_irq(pdev->irq, megasas_isr,
+		pci_dev_msi_enabled(pdev) ? 0 : IRQF_SHARED,
 		"megasas", instance)) {
 		printk(KERN_ERR "megasas: Failed to register IRQ\n");
 		goto fail_irq;
@@ -3443,6 +3453,8 @@ megasas_resume(struct pci_dev *pdev)
 	return 0;
 
 fail_irq:
+	pci_disable_msi(pdev);
+
 fail_init_mfi:
 	if (instance->evt_detail)
 		pci_free_consistent(pdev, sizeof(struct megasas_evt_detail),
@@ -3519,6 +3531,7 @@ static void __devexit megasas_detach_one
 	instance->instancet->disable_intr(instance->reg_set);
 
 	free_irq(instance->pdev->irq, instance);
+	pci_disable_msi(pdev);
 
 	megasas_release_mfi(instance);