isci: rely on irq core for intx multiplexing, and silence screaming intx

Remove the extra logic to poll each controller for interrupts, that's
the core's job for shared interrupts.

While testing noticed that a number of interrupts fire while waiting for
the completion tasklet to run, so added an irq-ack.

Reported-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/drivers/scsi/isci/init.c b/drivers/scsi/isci/init.c
index 015ce94..5a9cd5f 100644
--- a/drivers/scsi/isci/init.c
+++ b/drivers/scsi/isci/init.c
@@ -335,6 +335,7 @@
 static int isci_setup_interrupts(struct pci_dev *pdev)
 {
 	int err, i, num_msix;
+	struct isci_host *ihost;
 	struct isci_pci_info *pci_info = to_pci_info(pdev);
 
 	/*
@@ -353,9 +354,9 @@
 	for (i = 0; i < num_msix; i++) {
 		int id = i / SCI_NUM_MSI_X_INT;
 		struct msix_entry *msix = &pci_info->msix_entries[i];
-		struct isci_host *isci_host = pci_info->hosts[id];
 		irq_handler_t isr;
 
+		ihost = pci_info->hosts[id];
 		/* odd numbered vectors are error interrupts */
 		if (i & 1)
 			isr = isci_error_isr;
@@ -363,16 +364,16 @@
 			isr = isci_msix_isr;
 
 		err = devm_request_irq(&pdev->dev, msix->vector, isr, 0,
-				       DRV_NAME"-msix", isci_host);
+				       DRV_NAME"-msix", ihost);
 		if (!err)
 			continue;
 
 		dev_info(&pdev->dev, "msix setup failed falling back to intx\n");
 		while (i--) {
 			id = i / SCI_NUM_MSI_X_INT;
-			isci_host = pci_info->hosts[id];
+			ihost = pci_info->hosts[id];
 			msix = &pci_info->msix_entries[i];
-			devm_free_irq(&pdev->dev, msix->vector, isci_host);
+			devm_free_irq(&pdev->dev, msix->vector, ihost);
 		}
 		pci_disable_msix(pdev);
 		goto intx;
@@ -380,8 +381,12 @@
 	return 0;
 
  intx:
-	err = devm_request_irq(&pdev->dev, pdev->irq, isci_intx_isr,
-			       IRQF_SHARED, DRV_NAME"-intx", pdev);
+	for_each_isci_host(i, ihost, pdev) {
+		err = devm_request_irq(&pdev->dev, pdev->irq, isci_intx_isr,
+				       IRQF_SHARED, DRV_NAME"-intx", ihost);
+		if (err)
+			break;
+	}
 	return err;
 }