Revert "PCI/portdrv: Do not setup up IRQs if there are no users"

This reverts commit 0e8ae5a6.

0e8ae5a6 ("PCI/portdrv: Do not setup up IRQs if there are no users")
reduced usage of IRQs when we don't think we need them.  But Joey, Sergiu,
and David reported choppy GUI rendering, systems that became unresponsive
every few seconds, incorrect values reported by cpufreq, and high IRQ 16
CPU usage.

Joey bisected the issues to 0e8ae5a6, so revert it until we figure out
a better solution.

Link: https://lore.kernel.org/r/20220210222717.GA658201@bhelgaas
Link: https://bugzilla.kernel.org/show_bug.cgi?id=215533
Link: https://bugzilla.kernel.org/show_bug.cgi?id=215546Reported-by: Joey Corleone <joey.corleone@mail.ru>
Reported-by: Sergiu Deitsch <sergiu.deitsch@gmail.com>
Reported-by: David Spencer <dspencer577@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org	# v5.16+
Cc: Jan Kiszka <jan.kiszka@siemens.com>

drivers/pci/pcie/portdrv_core.c

@@ -166,6 +166,9 @@ static int pcie_init_service_irqs(struct pci_dev *dev, int *irqs, int mask)
 {
 	int ret, i;
 
+	for (i = 0; i < PCIE_PORT_DEVICE_MAXSERVICES; i++)
+		irqs[i] = -1;
+
 	/*
 	 * If we support PME but can't use MSI/MSI-X for it, we have to
 	 * fall back to INTx or other interrupts, e.g., a system shared
@@ -314,10 +317,8 @@ static int pcie_device_init(struct pci_dev *pdev, int service, int irq)
  */
 int pcie_port_device_register(struct pci_dev *dev)
 {
-	int status, capabilities, irq_services, i, nr_service;
-	int irqs[PCIE_PORT_DEVICE_MAXSERVICES] = {
-		[0 ... PCIE_PORT_DEVICE_MAXSERVICES-1] = -1
-	};
+	int status, capabilities, i, nr_service;
+	int irqs[PCIE_PORT_DEVICE_MAXSERVICES];
 
 	/* Enable PCI Express port device */
 	status = pci_enable_device(dev);
@@ -330,32 +331,18 @@ int pcie_port_device_register(struct pci_dev *dev)
 		return 0;
 
 	pci_set_master(dev);
-
-	irq_services = 0;
-	if (IS_ENABLED(CONFIG_PCIE_PME))
-		irq_services |= PCIE_PORT_SERVICE_PME;
-	if (IS_ENABLED(CONFIG_PCIEAER))
-		irq_services |= PCIE_PORT_SERVICE_AER;
-	if (IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE))
-		irq_services |= PCIE_PORT_SERVICE_HP;
-	if (IS_ENABLED(CONFIG_PCIE_DPC))
-		irq_services |= PCIE_PORT_SERVICE_DPC;
-	irq_services &= capabilities;
-
-	if (irq_services) {
-		/*
-		 * Initialize service IRQs. Don't use service devices that
-		 * require interrupts if there is no way to generate them.
-		 * However, some drivers may have a polling mode (e.g.
-		 * pciehp_poll_mode) that can be used in the absence of IRQs.
-		 * Allow them to determine if that is to be used.
-		 */
-		status = pcie_init_service_irqs(dev, irqs, irq_services);
-		if (status) {
-			irq_services &= PCIE_PORT_SERVICE_HP;
-			if (!irq_services)
-				goto error_disable;
-		}
+	/*
+	 * Initialize service irqs. Don't use service devices that
+	 * require interrupts if there is no way to generate them.
+	 * However, some drivers may have a polling mode (e.g. pciehp_poll_mode)
+	 * that can be used in the absence of irqs.  Allow them to determine
+	 * if that is to be used.
+	 */
+	status = pcie_init_service_irqs(dev, irqs, capabilities);
+	if (status) {
+		capabilities &= PCIE_PORT_SERVICE_HP;
+		if (!capabilities)
+			goto error_disable;
 	}
 
 	/* Allocate child services if any */