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>

drivers/scsi/isci/host.c

@@ -77,15 +77,12 @@ irqreturn_t isci_msix_isr(int vec, void *data)
 
 irqreturn_t isci_intx_isr(int vec, void *data)
 {
-	struct pci_dev *pdev = data;
-	struct isci_host *ihost;
 	irqreturn_t ret = IRQ_NONE;
-	int i;
-
-	for_each_isci_host(i, ihost, pdev) {
+	struct isci_host *ihost = data;
 	struct scic_sds_controller *scic = ihost->core_controller;
 
 	if (scic_sds_controller_isr(scic)) {
+		writel(SMU_ISR_COMPLETION, &scic->smu_registers->interrupt_status);
 		tasklet_schedule(&ihost->completion_tasklet);
 		ret = IRQ_HANDLED;
 	} else if (scic_sds_controller_error_isr(scic)) {
@@ -94,7 +91,6 @@ irqreturn_t isci_intx_isr(int vec, void *data)
 		spin_unlock(&ihost->scic_lock);
 		ret = IRQ_HANDLED;
 	}
-	}
 
 	return ret;
 }

drivers/scsi/isci/init.c

@@ -335,6 +335,7 @@ static int num_controllers(struct pci_dev *pdev)
 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 @@ static int isci_setup_interrupts(struct pci_dev *pdev)
 	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 @@ static int isci_setup_interrupts(struct pci_dev *pdev)
 			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 @@ static int isci_setup_interrupts(struct pci_dev *pdev)
 	return 0;
 
  intx:
+	for_each_isci_host(i, ihost, pdev) {
 		err = devm_request_irq(&pdev->dev, pdev->irq, isci_intx_isr,
-			       IRQF_SHARED, DRV_NAME"-intx", pdev);
+				       IRQF_SHARED, DRV_NAME"-intx", ihost);
+		if (err)
+			break;
+	}
 	return err;
 }