1 files changed, 24 insertions, 11 deletions

diff --git a/drivers/accel/qaic/qaic_drv.c b/drivers/accel/qaic/qaic_drv.c
index 6f58095767df..5eba5f03d3bf 100644
--- a/drivers/accel/qaic/qaic_drv.c
+++ b/drivers/accel/qaic/qaic_drv.c
@@ -424,14 +424,24 @@ static int init_msi(struct qaic_device *qdev, struct pci_dev *pdev)
 	int i;
 
 	/* Managed release since we use pcim_enable_device */
-	ret = pci_alloc_irq_vectors(pdev, 1, 32, PCI_IRQ_MSI);
-	if (ret < 0)
-		return ret;
+	ret = pci_alloc_irq_vectors(pdev, 32, 32, PCI_IRQ_MSI);
+	if (ret == -ENOSPC) {
+		ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI);
+		if (ret < 0)
+			return ret;
 
-	if (ret < 32) {
-		pci_err(pdev, "%s: Requested 32 MSIs. Obtained %d MSIs which is less than the 32 required.\n",
-			__func__, ret);
-		return -ENODEV;
+		/*
+		 * Operate in one MSI mode. All interrupts will be directed to
+		 * MSI0; every interrupt will wake up all the interrupt handlers
+		 * (MHI and DBC[0-15]). Since the interrupt is now shared, it is
+		 * not disabled during DBC threaded handler, but only one thread
+		 * will be allowed to run per DBC, so while it can be
+		 * interrupted, it shouldn't race with itself.
+		 */
+		qdev->single_msi = true;
+		pci_info(pdev, "Allocating 32 MSIs failed, operating in 1 MSI mode. Performance may be impacted.\n");
+	} else if (ret < 0) {
+		return ret;
 	}
 
 	mhi_irq = pci_irq_vector(pdev, 0);
@@ -439,15 +449,17 @@ static int init_msi(struct qaic_device *qdev, struct pci_dev *pdev)
 		return mhi_irq;
 
 	for (i = 0; i < qdev->num_dbc; ++i) {
-		ret = devm_request_threaded_irq(&pdev->dev, pci_irq_vector(pdev, i + 1),
+		ret = devm_request_threaded_irq(&pdev->dev,
+						pci_irq_vector(pdev, qdev->single_msi ? 0 : i + 1),
 						dbc_irq_handler, dbc_irq_threaded_fn, IRQF_SHARED,
 						"qaic_dbc", &qdev->dbc[i]);
 		if (ret)
 			return ret;
 
 		if (datapath_polling) {
-			qdev->dbc[i].irq = pci_irq_vector(pdev, i + 1);
-			disable_irq_nosync(qdev->dbc[i].irq);
+			qdev->dbc[i].irq = pci_irq_vector(pdev, qdev->single_msi ? 0 : i + 1);
+			if (!qdev->single_msi)
+				disable_irq_nosync(qdev->dbc[i].irq);
 			INIT_WORK(&qdev->dbc[i].poll_work, irq_polling_work);
 		}
 	}
@@ -479,7 +491,8 @@ static int qaic_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		goto cleanup_qdev;
 	}
 
-	qdev->mhi_cntrl = qaic_mhi_register_controller(pdev, qdev->bar_0, mhi_irq);
+	qdev->mhi_cntrl = qaic_mhi_register_controller(pdev, qdev->bar_0, mhi_irq,
+						       qdev->single_msi);
 	if (IS_ERR(qdev->mhi_cntrl)) {
 		ret = PTR_ERR(qdev->mhi_cntrl);
 		goto cleanup_qdev;