wil6210: work around for platforms with broken INTx

There are platforms where INTx can't be routed by ACPI,
this leads to pci_enable_device failure. Re-try pretending we have
MSI already configured; in this case pci_enable_device do not try
to configure INTx. However, MSI could still work.

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/wil6210/pcie_bus.c

@@ -35,6 +35,13 @@ static int wil_if_pcie_enable(struct wil6210_priv *wil)
 {
 	struct pci_dev *pdev = wil->pdev;
 	int rc;
+	/* on platforms with buggy ACPI, pdev->msi_enabled may be set to
+	 * allow pci_enable_device to work. This indicates INTx was not routed
+	 * and only MSI should be used
+	 */
+	int msi_only = pdev->msi_enabled;
+
+	pdev->msi_enabled = 0;
 
 	pci_set_master(pdev);
 
@@ -66,6 +73,12 @@ static int wil_if_pcie_enable(struct wil6210_priv *wil)
 
 	wil->n_msi = use_msi;
 
+	if ((wil->n_msi == 0) && msi_only) {
+		wil_err(wil, "Interrupt pin not routed, unable to use INTx\n");
+		rc = -ENODEV;
+		goto stop_master;
+	}
+
 	rc = wil6210_init_irq(wil, pdev->irq);
 	if (rc)
 		goto stop_master;
@@ -124,9 +137,16 @@ static int wil_pcie_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 
 	rc = pci_enable_device(pdev);
 	if (rc) {
-		dev_err(&pdev->dev, "pci_enable_device failed\n");
-		return -ENODEV;
+		dev_err(&pdev->dev,
+			"pci_enable_device failed, retry with MSI only\n");
+		/* Work around for platforms that can't allocate IRQ:
+		 * retry with MSI only
+		 */
+		pdev->msi_enabled = 1;
+		rc = pci_enable_device(pdev);
 	}
+	if (rc)
+		return -ENODEV;
 	/* rollback to err_disable_pdev */
 
 	rc = pci_request_region(pdev, 0, WIL_NAME);