ioat: kill msix_single_vector support

Once we have determined that we will not have all of our desired msix
vectors there is no point in attempting a single msix allocation.  The
driver will already need to read registers to determine the source of
the interrupt the fact that it is msix is moot.  Fallback directly to
msi.
Reported-by: Alexander Gordeev <agordeev@redhat.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/dma/ioat/dma.c

@@ -869,8 +869,7 @@ static char ioat_interrupt_style[32] = "msix";
 module_param_string(ioat_interrupt_style, ioat_interrupt_style,
 		    sizeof(ioat_interrupt_style), 0644);
 MODULE_PARM_DESC(ioat_interrupt_style,
-		 "set ioat interrupt style: msix (default), "
-		 "msix-single-vector, msi, intx)");
+		 "set ioat interrupt style: msix (default), msi, intx");
 
 /**
  * ioat_dma_setup_interrupts - setup interrupt handler
@@ -888,8 +887,6 @@ int ioat_dma_setup_interrupts(struct ioatdma_device *device)
 
 	if (!strcmp(ioat_interrupt_style, "msix"))
 		goto msix;
-	if (!strcmp(ioat_interrupt_style, "msix-single-vector"))
-		goto msix_single_vector;
 	if (!strcmp(ioat_interrupt_style, "msi"))
 		goto msi;
 	if (!strcmp(ioat_interrupt_style, "intx"))
@@ -904,10 +901,8 @@ int ioat_dma_setup_interrupts(struct ioatdma_device *device)
 		device->msix_entries[i].entry = i;
 
 	err = pci_enable_msix(pdev, device->msix_entries, msixcnt);
-	if (err < 0)
+	if (err)
 		goto msi;
-	if (err > 0)
-		goto msix_single_vector;
 
 	for (i = 0; i < msixcnt; i++) {
 		msix = &device->msix_entries[i];
@@ -921,29 +916,13 @@ int ioat_dma_setup_interrupts(struct ioatdma_device *device)
 				chan = ioat_chan_by_index(device, j);
 				devm_free_irq(dev, msix->vector, chan);
 			}
-			goto msix_single_vector;
+			goto msi;
 		}
 	}
 	intrctrl |= IOAT_INTRCTRL_MSIX_VECTOR_CONTROL;
 	device->irq_mode = IOAT_MSIX;
 	goto done;
 
-msix_single_vector:
-	msix = &device->msix_entries[0];
-	msix->entry = 0;
-	err = pci_enable_msix(pdev, device->msix_entries, 1);
-	if (err)
-		goto msi;
-
-	err = devm_request_irq(dev, msix->vector, ioat_dma_do_interrupt, 0,
-			       "ioat-msix", device);
-	if (err) {
-		pci_disable_msix(pdev);
-		goto msi;
-	}
-	device->irq_mode = IOAT_MSIX_SINGLE;
-	goto done;
-
 msi:
 	err = pci_enable_msi(pdev);
 	if (err)

drivers/dma/ioat/dma.h

@@ -52,7 +52,6 @@
 enum ioat_irq_mode {
 	IOAT_NOIRQ = 0,
 	IOAT_MSIX,
-	IOAT_MSIX_SINGLE,
 	IOAT_MSI,
 	IOAT_INTX
 };

drivers/dma/ioat/dma_v3.c

@@ -1468,13 +1468,6 @@ static int ioat3_irq_reinit(struct ioatdma_device *device)
 		pci_disable_msix(pdev);
 		break;
 
-	case IOAT_MSIX_SINGLE:
-		msix = &device->msix_entries[0];
-		chan = ioat_chan_by_index(device, 0);
-		devm_free_irq(&pdev->dev, msix->vector, chan);
-		pci_disable_msix(pdev);
-		break;
-
 	case IOAT_MSI:
 		chan = ioat_chan_by_index(device, 0);
 		devm_free_irq(&pdev->dev, pdev->irq, chan);