Re: [PATCH] PCI: vgaarb: Include 0x0380 devices in default selection
From: Mario Limonciello
Date: Mon Jun 22 2026 - 00:00:23 EST
On 6/21/26 20:50, Aaron Ma wrote:
On Mon, Jun 22, 2026 at 1:15 AM Mario Limonciello
<mario.limonciello@xxxxxxx> wrote:
On 6/18/26 01:18, Aaron Ma wrote:
Some firmware boot GPUs report class 0x0380 (PCI_CLASS_DISPLAY_OTHER)> > if (a == &dev_attr_serial_number.attr && pci_get_dsn(pdev))
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;
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
This patch doesn't seem correct to me. It's overloading the purpose of
boot_vga to cover non VGA devices. We should be using boot_display.
Trying to hypothesize what's going on here - I guess you're seeing
boot_display set for more than one device due to enumeration order.
Can you see if this helps instead?
╰─❯ git diff
diff --git a/arch/x86/video/video-common.c b/arch/x86/video/video-common.c
index 152789f00fcda..9440eb3a7b15d 100644
--- a/arch/x86/video/video-common.c
+++ b/arch/x86/video/video-common.c
@@ -43,9 +43,6 @@ bool video_is_primary_device(struct device *dev)
if (!pci_is_display(pdev))
return false;
- if (pdev == vga_default_device())
- return true;
-
#ifdef CONFIG_SCREEN_INFO
numres = screen_info_resources(si, res, ARRAY_SIZE(res));
for (i = 0; i < numres; ++i) {
Hi Mario,
I tested your change. boot_display becomes correct, but the issue is not fixed.
The kernel state becomes:
AMD: boot_display=1, boot_vga absent
NVIDIA: boot_display absent, boot_vga=1
Current Xorg checks boot_display || boot_vga, so both GPUs still match.
The selected primary GPU still depends on Xorg's DRM device enumeration order.
So boot_vga is still wrong, and that still matters. The kernel should not
expose boot_vga=1 for NVIDIA when the firmware framebuffer is on AMD.
My patch makes boot_vga and boot_display agree on the AMD boot display.
Thanks,
Aaron
Got it. I still don't think it's correct to overload boot_vga. It would be better for us to not show boot_vga at all - because it's not correct.
Maybe we should drop the fallback code in VGA arbiter that is setting NVIDIA as boot_vga at all.
Could you look at doing that?