misc: pci_endpoint_test: Defer IRQ allocation until ioctl(PCITEST_SET_IRQTYPE)

Commit a402006 ("misc: pci_endpoint_test: Remove global 'irq_type'
and 'no_msi'") changed so that the default IRQ vector requested by
pci_endpoint_test_probe() was no longer the module param 'irq_type', but
instead test->irq_type. test->irq_type is by default IRQ_TYPE_UNDEFINED
(until someone calls ioctl(PCITEST_SET_IRQTYPE)).

However, the commit also changed so that after initializing test->irq_type
to IRQ_TYPE_UNDEFINED, it also overrides it with driver_data->irq_type, if
the PCI device and vendor ID provides driver_data.

This causes a regression for PCI device and vendor IDs that do not provide
driver_data, and the host side pci_endpoint_test_driver driver failed to
probe on such platforms:

  pci-endpoint-test 0001:01:00.0: Invalid IRQ type selected
  pci-endpoint-test 0001:01:00.0: probe with driver pci-endpoint-test failed with error -22

Considering that the pci endpoint selftests and the old pcitest.sh always
call ioctl(PCITEST_SET_IRQTYPE) before performing any test that requires
IRQs, fix the regression by removing the allocation of IRQs in
pci_endpoint_test_probe().  The IRQ allocation will occur when
ioctl(PCITEST_SET_IRQTYPE) is called.

A positive side effect of this is that even if the endpoint controller has
issues with IRQs, the user can do still do all the tests/ioctls() that do
not require working IRQs, e.g. PCITEST_BAR and PCITEST_BARS.

This also means that we can remove the now unused irq_type from
driver_data. The irq_type will always be the one configured by the user
using ioctl(PCITEST_SET_IRQTYPE). (A user that does not know, or care
which irq_type that is used, can use PCITEST_IRQ_TYPE_AUTO. This has
superseded the need for a default irq_type in driver_data.)

[bhelgaas: add probe failure details]
Fixes: a402006 ("misc: pci_endpoint_test: Remove global 'irq_type' and 'no_msi'")
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20250416142825.336554-2-cassel@kernel.org

Author: floatious

drivers/misc/pci_endpoint_test.c

@@ -122,7 +122,6 @@ struct pci_endpoint_test {
 struct pci_endpoint_test_data {
 	enum pci_barno test_reg_bar;
 	size_t alignment;
-	int irq_type;
 };
 
 static inline u32 pci_endpoint_test_readl(struct pci_endpoint_test *test,
@@ -948,7 +947,6 @@ static int pci_endpoint_test_probe(struct pci_dev *pdev,
 		test_reg_bar = data->test_reg_bar;
 		test->test_reg_bar = test_reg_bar;
 		test->alignment = data->alignment;
-		test->irq_type = data->irq_type;
 	}
 
 	init_completion(&test->irq_raised);
@@ -970,10 +968,6 @@ static int pci_endpoint_test_probe(struct pci_dev *pdev,
 
 	pci_set_master(pdev);
 
-	ret = pci_endpoint_test_alloc_irq_vectors(test, test->irq_type);
-	if (ret)
-		goto err_disable_irq;
-
 	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
 		if (pci_resource_flags(pdev, bar) & IORESOURCE_MEM) {
 			base = pci_ioremap_bar(pdev, bar);
@@ -1009,18 +1003,14 @@ static int pci_endpoint_test_probe(struct pci_dev *pdev,
 		goto err_ida_remove;
 	}
 
-	ret = pci_endpoint_test_request_irq(test);
-	if (ret)
-		goto err_kfree_test_name;
-
 	pci_endpoint_test_get_capabilities(test);
 
 	misc_device = &test->miscdev;
 	misc_device->minor = MISC_DYNAMIC_MINOR;
 	misc_device->name = kstrdup(name, GFP_KERNEL);
 	if (!misc_device->name) {
 		ret = -ENOMEM;
-		goto err_release_irq;
+		goto err_kfree_test_name;
 	}
 	misc_device->parent = &pdev->dev;
 	misc_device->fops = &pci_endpoint_test_fops;
@@ -1036,9 +1026,6 @@ static int pci_endpoint_test_probe(struct pci_dev *pdev,
 err_kfree_name:
 	kfree(misc_device->name);
 
-err_release_irq:
-	pci_endpoint_test_release_irq(test);
-
 err_kfree_test_name:
 	kfree(test->name);
 
@@ -1051,8 +1038,6 @@ static int pci_endpoint_test_probe(struct pci_dev *pdev,
 			pci_iounmap(pdev, test->bar[bar]);
 	}
 
-err_disable_irq:
-	pci_endpoint_test_free_irq_vectors(test);
 	pci_release_regions(pdev);
 
 err_disable_pdev:
@@ -1092,23 +1077,19 @@ static void pci_endpoint_test_remove(struct pci_dev *pdev)
 static const struct pci_endpoint_test_data default_data = {
 	.test_reg_bar = BAR_0,
 	.alignment = SZ_4K,
-	.irq_type = PCITEST_IRQ_TYPE_MSI,
 };
 
 static const struct pci_endpoint_test_data am654_data = {
 	.test_reg_bar = BAR_2,
 	.alignment = SZ_64K,
-	.irq_type = PCITEST_IRQ_TYPE_MSI,
 };
 
 static const struct pci_endpoint_test_data j721e_data = {
 	.alignment = 256,
-	.irq_type = PCITEST_IRQ_TYPE_MSI,
 };
 
 static const struct pci_endpoint_test_data rk3588_data = {
 	.alignment = SZ_64K,
-	.irq_type = PCITEST_IRQ_TYPE_MSI,
 };
 
 /*