[PATCH] PCI: vgaarb: Include 0x0380 devices in default selection

[Aaron Ma]

Some firmware boot GPUs report class 0x0380 (PCI_CLASS_DISPLAY_OTHER)
instead of PCI_CLASS_DISPLAY_VGA. vgaarb only registers pci_is_vga()
devices, so those GPUs are not considered by vga_is_firmware_default().

On these systems the AMD GPU matches the EFI framebuffer but is
excluded from vgaarb because it is class 0x0380, while the NVIDIA GPU
does not match the EFI framebuffer but becomes vga_default_device()
through the vgaarb's enabled-device fallback.

Register legacy VGA and 0x0380 devices in vgaarb, and expose boot_vga
for the same set of devices, so the firmware default device can be
selected correctly.

Signed-off-by: Aaron Ma <aaron.ma@xxxxxxxxxxxxx>
---
 drivers/pci/pci-sysfs.c |  3 ++-
 drivers/pci/vgaarb.c    | 10 +++++-----
 include/linux/pci.h     | 14 ++++++++++++++
 3 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index d37860841260c..843d83ec9550a 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1717,7 +1717,8 @@ static umode_t pci_dev_attrs_are_visible(struct kobject *kobj,
 	struct device *dev = kobj_to_dev(kobj);
 	struct pci_dev *pdev = to_pci_dev(dev);
 
-	if (a == &dev_attr_boot_vga.attr && pci_is_vga(pdev))
+	if (a == &dev_attr_boot_vga.attr &&
+	    pci_is_vga_or_other_display(pdev))
 		return a->mode;
 
 	if (a == &dev_attr_serial_number.attr && pci_get_dsn(pdev))
diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
index c360eee11dd9e..0e0878189e3d8 100644
--- a/drivers/pci/vgaarb.c
+++ b/drivers/pci/vgaarb.c
@@ -796,7 +796,7 @@ static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
 	}
 
 	if (vga_is_boot_device(vgadev)) {
-		vgaarb_info(&pdev->dev, "setting as boot VGA device%s\n",
+		vgaarb_info(&pdev->dev, "setting as boot display device%s\n",
 			    vga_default_device() ?
 			    " (overriding previous)" : "");
 		vga_set_default_device(pdev);
@@ -1483,8 +1483,8 @@ static int pci_notify(struct notifier_block *nb, unsigned long action,
 
 	vgaarb_dbg(dev, "%s\n", __func__);
 
-	/* Only deal with VGA class devices */
-	if (!pci_is_vga(pdev))
+	/* Only deal with legacy VGA and other display controller devices */
+	if (!pci_is_vga_or_other_display(pdev))
 		return 0;
 
 	/*
@@ -1530,12 +1530,12 @@ static int __init vga_arb_device_init(void)
 
 	bus_register_notifier(&pci_bus_type, &pci_notifier);
 
-	/* Add all VGA class PCI devices by default */
+	/* Add legacy VGA and other display controller PCI devices by default */
 	pdev = NULL;
 	while ((pdev =
 		pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
 			       PCI_ANY_ID, pdev)) != NULL) {
-		if (pci_is_vga(pdev))
+		if (pci_is_vga_or_other_display(pdev))
 			vga_arbiter_add_pci_device(pdev);
 	}
 
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 2c4454583c115..195ec1bdac863 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -792,6 +792,20 @@ static inline bool pci_is_vga(struct pci_dev *pdev)
 	return false;
 }
 
+/**
+ * pci_is_vga_or_other_display - check if the PCI device is VGA or 0x0380
+ * @pdev: PCI device
+ *
+ * Return true for legacy VGA-compatible devices and for "other display
+ * controller" devices.  Some firmware-selected boot display devices expose
+ * class 0x0380 instead of PCI_CLASS_DISPLAY_VGA.
+ */
+static inline bool pci_is_vga_or_other_display(struct pci_dev *pdev)
+{
+	return pci_is_vga(pdev) ||
+		(pdev->class >> 8) == PCI_CLASS_DISPLAY_OTHER;
+}
+
 /**
  * pci_is_display - check if the PCI device is a display controller
  * @pdev: PCI device
-- 
2.43.0