[PATCH v3 3/7] thermal: int340x: processor_thermal: Use non MSI interrupts by default

[Srinivas Pandruvada]

There are issues in using MSI interrupts for processor thermal device.
The support is not consistent across generations. But the legacy PCI
interrupts work on all current generations.

Hence always use legacy PCI interrupts by default, instead of MSI.
Add a module param to use of MSI, so that MSI can be still used.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>
---
v3:
Address comments from Rafel for:
replace variable msi_enabled to use_msi
Add bus mastering for legacy PCI, even if it doesn't make any difference
Use module param along with pci device msi enabled to use MSI

v2:
Changed msi_enabled to type bool

 .../processor_thermal_device_pci.c            | 30 +++++++++++++------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/drivers/thermal/intel/int340x_thermal/processor_thermal_device_pci.c b/drivers/thermal/intel/int340x_thermal/processor_thermal_device_pci.c
index 314a726f35c7..f736688abe9b 100644
--- a/drivers/thermal/intel/int340x_thermal/processor_thermal_device_pci.c
+++ b/drivers/thermal/intel/int340x_thermal/processor_thermal_device_pci.c
@@ -15,6 +15,11 @@
 
 #define DRV_NAME "proc_thermal_pci"
 
+static bool use_msi;
+module_param(use_msi, bool, 0644);
+MODULE_PARM_DESC(use_msi,
+	"Use PCI MSI based interrupts for processor thermal device.");
+
 struct proc_thermal_pci {
 	struct pci_dev *pdev;
 	struct proc_thermal_device *proc_priv;
@@ -203,6 +208,7 @@ static int proc_thermal_pci_probe(struct pci_dev *pdev, const struct pci_device_
 	struct proc_thermal_device *proc_priv;
 	struct proc_thermal_pci *pci_info;
 	int irq_flag = 0, irq, ret;
+	bool msi_irq = false;
 
 	proc_priv = devm_kzalloc(&pdev->dev, sizeof(*proc_priv), GFP_KERNEL);
 	if (!proc_priv)
@@ -248,16 +254,21 @@ static int proc_thermal_pci_probe(struct pci_dev *pdev, const struct pci_device_
 		goto err_ret_mmio;
 	}
 
-	/* request and enable interrupt */
-	ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_ALL_TYPES);
-	if (ret < 0) {
-		dev_err(&pdev->dev, "Failed to allocate vectors!\n");
-		goto err_ret_tzone;
-	}
-	if (!pdev->msi_enabled && !pdev->msix_enabled)
+	if (use_msi && (pdev->msi_enabled || pdev->msix_enabled)) {
+		/* request and enable interrupt */
+		ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_ALL_TYPES);
+		if (ret < 0) {
+			dev_err(&pdev->dev, "Failed to allocate vectors!\n");
+			goto err_ret_tzone;
+		}
+
+		irq =  pci_irq_vector(pdev, 0);
+		msi_irq = true;
+	} else {
 		irq_flag = IRQF_SHARED;
+		irq = pdev->irq;
+	}
 
-	irq =  pci_irq_vector(pdev, 0);
 	ret = devm_request_threaded_irq(&pdev->dev, irq,
 					proc_thermal_irq_handler, NULL,
 					irq_flag, KBUILD_MODNAME, pci_info);
@@ -273,7 +284,8 @@ static int proc_thermal_pci_probe(struct pci_dev *pdev, const struct pci_device_
 	return 0;
 
 err_free_vectors:
-	pci_free_irq_vectors(pdev);
+	if (msi_irq)
+		pci_free_irq_vectors(pdev);
 err_ret_tzone:
 	thermal_zone_device_unregister(pci_info->tzone);
 err_ret_mmio:
-- 
2.40.1