[PATCH v4 0/8] Adjust fbcon console device detection

[PATCH v4 0/8] Adjust fbcon console device detection

[Mario Limonciello]

From: Mario Limonciello <mario.limonciello@amd.com>

This series started out as changes to VGA arbiter to try to handle a case
of a system with 2 GPUs that are not VGA devices [1].  This was discussed
but decided not to overload the VGA arbiter for non VGA devices.

Instead move the x86 specific detection of framebuffer resources into x86
specific code that the fbcon can use to properly identify the primary
device. This code is still called from the VGA arbiter, and the logic does
not change there. To avoid regression default to VGA arbiter and only fall
back to looking up with x86 specific detection method.

In order for userspace to also be able to discover which device was the
primary video display device create a new sysfs file 'boot_display'.

Mario Limonciello (8):
  PCI: Add helper for checking if a PCI device is a display controller
  vfio/pci: Use pci_is_display()
  vga_switcheroo: Use pci_is_display()
  iommu/vt-d: Use pci_is_display()
  ALSA: hda: Use pci_is_display()
  Fix access to video_is_primary_device() when compiled without
    CONFIG_VIDEO
  PCI/VGA: Move check for firmware default out of VGA arbiter
  PCI: Add a new 'boot_display' attribute

 Documentation/ABI/testing/sysfs-bus-pci |  9 +++++++
 arch/parisc/include/asm/video.h         |  2 +-
 arch/sparc/include/asm/video.h          |  2 ++
 arch/x86/include/asm/video.h            |  2 ++
 arch/x86/video/video-common.c           | 13 ++++++++-
 drivers/gpu/vga/vga_switcheroo.c        |  2 +-
 drivers/iommu/intel/iommu.c             |  2 +-
 drivers/pci/pci-sysfs.c                 | 14 ++++++++++
 drivers/pci/vgaarb.c                    | 36 ++-----------------------
 drivers/vfio/pci/vfio_pci_igd.c         |  3 +--
 include/linux/pci.h                     | 15 +++++++++++
 sound/hda/hdac_i915.c                   |  2 +-
 sound/pci/hda/hda_intel.c               |  4 +--
 13 files changed, 63 insertions(+), 43 deletions(-)


base-commit: 86731a2a651e58953fc949573895f2fa6d456841
-- 
2.43.0

[PATCH v4 1/8] PCI: Add helper for checking if a PCI device is a display controller

[Mario Limonciello]

From: Mario Limonciello <mario.limonciello@amd.com>

Several places in the kernel do class shifting to match whether a
PCI device is display class.  Introduce a helper for those places to
use.

Reviewed-by: Daniel Dadap <ddadap@nvidia.com>
Reviewed-by: Simona Vetter <simona.vetter@ffwll.ch>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 include/linux/pci.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 05e68f35f3923..e77754e43c629 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -744,6 +744,21 @@ static inline bool pci_is_vga(struct pci_dev *pdev)
 	return false;
 }
 
+/**
+ * pci_is_display - Check if a PCI device is a display controller
+ * @pdev: Pointer to the PCI device structure
+ *
+ * This function determines whether the given PCI device corresponds
+ * to a display controller. Display controllers are typically used
+ * for graphical output and are identified based on their class code.
+ *
+ * Return: true if the PCI device is a display controller, false otherwise.
+ */
+static inline bool pci_is_display(struct pci_dev *pdev)
+{
+	return (pdev->class >> 16) == PCI_BASE_CLASS_DISPLAY;
+}
+
 #define for_each_pci_bridge(dev, bus)				\
 	list_for_each_entry(dev, &bus->devices, bus_list)	\
 		if (!pci_is_bridge(dev)) {} else
-- 
2.43.0

[PATCH v4 2/8] vfio/pci: Use pci_is_display()

[Mario Limonciello]

From: Mario Limonciello <mario.limonciello@amd.com>

The inline pci_is_display() helper does the same thing.  Use it.

Acked-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Daniel Dadap <ddadap@nvidia.com>
Reviewed-by: Simona Vetter <simona.vetter@ffwll.ch>
Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/vfio/pci/vfio_pci_igd.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci_igd.c b/drivers/vfio/pci/vfio_pci_igd.c
index ef490a4545f48..988b6919c2c31 100644
--- a/drivers/vfio/pci/vfio_pci_igd.c
+++ b/drivers/vfio/pci/vfio_pci_igd.c
@@ -437,8 +437,7 @@ static int vfio_pci_igd_cfg_init(struct vfio_pci_core_device *vdev)
 
 bool vfio_pci_is_intel_display(struct pci_dev *pdev)
 {
-	return (pdev->vendor == PCI_VENDOR_ID_INTEL) &&
-	       ((pdev->class >> 16) == PCI_BASE_CLASS_DISPLAY);
+	return (pdev->vendor == PCI_VENDOR_ID_INTEL) && pci_is_display(pdev);
 }
 
 int vfio_pci_igd_init(struct vfio_pci_core_device *vdev)
-- 
2.43.0

[PATCH v4 3/8] vga_switcheroo: Use pci_is_display()

[Mario Limonciello]

From: Mario Limonciello <mario.limonciello@amd.com>

The inline pci_is_display() helper does the same thing.  Use it.

Reviewed-by: Daniel Dadap <ddadap@nvidia.com>
Reviewed-by: Simona Vetter <simona.vetter@ffwll.ch>
Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/gpu/vga/vga_switcheroo.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c
index 18f2c92beff8e..68e45a26e85f7 100644
--- a/drivers/gpu/vga/vga_switcheroo.c
+++ b/drivers/gpu/vga/vga_switcheroo.c
@@ -437,7 +437,7 @@ find_active_client(struct list_head *head)
  */
 bool vga_switcheroo_client_probe_defer(struct pci_dev *pdev)
 {
-	if ((pdev->class >> 16) == PCI_BASE_CLASS_DISPLAY) {
+	if (pci_is_display(pdev)) {
 		/*
 		 * apple-gmux is needed on pre-retina MacBook Pro
 		 * to probe the panel if pdev is the inactive GPU.
-- 
2.43.0

[PATCH v4 4/8] iommu/vt-d: Use pci_is_display()

[Mario Limonciello]

From: Mario Limonciello <mario.limonciello@amd.com>

The inline pci_is_display() helper does the same thing.  Use it.

Reviewed-by: Daniel Dadap <ddadap@nvidia.com>
Reviewed-by: Simona Vetter <simona.vetter@ffwll.ch>
Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/iommu/intel/iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 7aa3932251b2f..17267cd476ce7 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -34,7 +34,7 @@
 #define ROOT_SIZE		VTD_PAGE_SIZE
 #define CONTEXT_SIZE		VTD_PAGE_SIZE
 
-#define IS_GFX_DEVICE(pdev) ((pdev->class >> 16) == PCI_BASE_CLASS_DISPLAY)
+#define IS_GFX_DEVICE(pdev) pci_is_display(pdev)
 #define IS_USB_DEVICE(pdev) ((pdev->class >> 8) == PCI_CLASS_SERIAL_USB)
 #define IS_ISA_DEVICE(pdev) ((pdev->class >> 8) == PCI_CLASS_BRIDGE_ISA)
 #define IS_AZALIA(pdev) ((pdev)->vendor == 0x8086 && (pdev)->device == 0x3a3e)
-- 
2.43.0

[PATCH v4 5/8] ALSA: hda: Use pci_is_display()

[Mario Limonciello]

From: Mario Limonciello <mario.limonciello@amd.com>

The inline pci_is_display() helper does the same thing.  Use it.

Reviewed-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Daniel Dadap <ddadap@nvidia.com>
Reviewed-by: Simona Vetter <simona.vetter@ffwll.ch>
Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 sound/hda/hdac_i915.c     | 2 +-
 sound/pci/hda/hda_intel.c | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/sound/hda/hdac_i915.c b/sound/hda/hdac_i915.c
index e9425213320ea..44438c799f957 100644
--- a/sound/hda/hdac_i915.c
+++ b/sound/hda/hdac_i915.c
@@ -155,7 +155,7 @@ static int i915_gfx_present(struct pci_dev *hdac_pci)
 
 	for_each_pci_dev(display_dev) {
 		if (display_dev->vendor != PCI_VENDOR_ID_INTEL ||
-		    (display_dev->class >> 16) != PCI_BASE_CLASS_DISPLAY)
+		    !pci_is_display(display_dev))
 			continue;
 
 		if (pci_match_id(denylist, display_dev))
diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index 439cf1bda6e66..75badb5c69b8e 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -1465,7 +1465,7 @@ static struct pci_dev *get_bound_vga(struct pci_dev *pci)
 				 * the dGPU is the one who is involved in
 				 * vgaswitcheroo.
 				 */
-				if (((p->class >> 16) == PCI_BASE_CLASS_DISPLAY) &&
+				if (pci_is_display(p) &&
 				    (atpx_present() || apple_gmux_detect(NULL, NULL)))
 					return p;
 				pci_dev_put(p);
@@ -1477,7 +1477,7 @@ static struct pci_dev *get_bound_vga(struct pci_dev *pci)
 			p = pci_get_domain_bus_and_slot(pci_domain_nr(pci->bus),
 							pci->bus->number, 0);
 			if (p) {
-				if ((p->class >> 16) == PCI_BASE_CLASS_DISPLAY)
+				if (pci_is_display(p))
 					return p;
 				pci_dev_put(p);
 			}
-- 
2.43.0

[PATCH v4 6/8] Fix access to video_is_primary_device() when compiled without CONFIG_VIDEO

[Mario Limonciello]

From: Mario Limonciello <mario.limonciello@amd.com>

When compiled without CONFIG_VIDEO the architecture specific
implementations of video_is_primary_device() include prototypes and
assume that video-common.c will be linked. Guard against this so that the
fallback inline implementation that returns false will be used when
compiled without CONFIG_VIDEO.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202506221312.49Fy1aNA-lkp@intel.com/
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
v4:
 * new patch
---
 arch/parisc/include/asm/video.h | 2 +-
 arch/sparc/include/asm/video.h  | 2 ++
 arch/x86/include/asm/video.h    | 2 ++
 3 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/parisc/include/asm/video.h b/arch/parisc/include/asm/video.h
index c5dff3223194a..a9d50ebd6e769 100644
--- a/arch/parisc/include/asm/video.h
+++ b/arch/parisc/include/asm/video.h
@@ -6,7 +6,7 @@
 
 struct device;
 
-#if defined(CONFIG_STI_CORE)
+#if defined(CONFIG_STI_CORE) && defined(CONFIG_VIDEO)
 bool video_is_primary_device(struct device *dev);
 #define video_is_primary_device video_is_primary_device
 #endif
diff --git a/arch/sparc/include/asm/video.h b/arch/sparc/include/asm/video.h
index a6f48f52db584..773717b6d4914 100644
--- a/arch/sparc/include/asm/video.h
+++ b/arch/sparc/include/asm/video.h
@@ -19,8 +19,10 @@ static inline pgprot_t pgprot_framebuffer(pgprot_t prot,
 #define pgprot_framebuffer pgprot_framebuffer
 #endif
 
+#ifdef CONFIG_VIDEO
 bool video_is_primary_device(struct device *dev);
 #define video_is_primary_device video_is_primary_device
+#endif
 
 static inline void fb_memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
 {
diff --git a/arch/x86/include/asm/video.h b/arch/x86/include/asm/video.h
index 0950c9535fae9..08ec328203ef8 100644
--- a/arch/x86/include/asm/video.h
+++ b/arch/x86/include/asm/video.h
@@ -13,8 +13,10 @@ pgprot_t pgprot_framebuffer(pgprot_t prot,
 			    unsigned long offset);
 #define pgprot_framebuffer pgprot_framebuffer
 
+#ifdef CONFIG_VIDEO
 bool video_is_primary_device(struct device *dev);
 #define video_is_primary_device video_is_primary_device
+#endif
 
 #include <asm-generic/video.h>
 
-- 
2.43.0

[PATCH v4 7/8] PCI/VGA: Move check for firmware default out of VGA arbiter

[Mario Limonciello]

From: Mario Limonciello <mario.limonciello@amd.com>

The x86 specific check for whether a framebuffer belongs to a device
works for display devices as well as VGA devices.  Callers to
video_is_primary_device() can benefit from checking non-VGA display
devices.

Move the x86 specific check into x86 specific code, and adjust VGA
arbiter to call that code as well. This allows fbcon to find the
right PCI device on systems that don't have VGA devices.

Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
v4:
 * use helper
---
 arch/x86/video/video-common.c | 13 ++++++++++++-
 drivers/pci/vgaarb.c          | 36 ++---------------------------------
 2 files changed, 14 insertions(+), 35 deletions(-)

diff --git a/arch/x86/video/video-common.c b/arch/x86/video/video-common.c
index 81fc97a2a837a..917568e4d7fb1 100644
--- a/arch/x86/video/video-common.c
+++ b/arch/x86/video/video-common.c
@@ -9,6 +9,7 @@
 
 #include <linux/module.h>
 #include <linux/pci.h>
+#include <linux/screen_info.h>
 #include <linux/vgaarb.h>
 
 #include <asm/video.h>
@@ -27,6 +28,7 @@ EXPORT_SYMBOL(pgprot_framebuffer);
 
 bool video_is_primary_device(struct device *dev)
 {
+	struct screen_info *si = &screen_info;
 	struct pci_dev *pdev;
 
 	if (!dev_is_pci(dev))
@@ -34,7 +36,16 @@ bool video_is_primary_device(struct device *dev)
 
 	pdev = to_pci_dev(dev);
 
-	return (pdev == vga_default_device());
+	if (!pci_is_display(pdev))
+		return false;
+
+	if (pdev == vga_default_device())
+		return true;
+
+	if (pdev == screen_info_pci_dev(si))
+		return true;
+
+	return false;
 }
 EXPORT_SYMBOL(video_is_primary_device);
 
diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
index 78748e8d2dbae..15ab58c70b016 100644
--- a/drivers/pci/vgaarb.c
+++ b/drivers/pci/vgaarb.c
@@ -26,12 +26,12 @@
 #include <linux/poll.h>
 #include <linux/miscdevice.h>
 #include <linux/slab.h>
-#include <linux/screen_info.h>
 #include <linux/vt.h>
 #include <linux/console.h>
 #include <linux/acpi.h>
 #include <linux/uaccess.h>
 #include <linux/vgaarb.h>
+#include <asm/video.h>
 
 static void vga_arbiter_notify_clients(void);
 
@@ -554,38 +554,6 @@ void vga_put(struct pci_dev *pdev, unsigned int rsrc)
 }
 EXPORT_SYMBOL(vga_put);
 
-static bool vga_is_firmware_default(struct pci_dev *pdev)
-{
-#if defined(CONFIG_X86)
-	u64 base = screen_info.lfb_base;
-	u64 size = screen_info.lfb_size;
-	struct resource *r;
-	u64 limit;
-
-	/* Select the device owning the boot framebuffer if there is one */
-
-	if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
-		base |= (u64)screen_info.ext_lfb_base << 32;
-
-	limit = base + size;
-
-	/* Does firmware framebuffer belong to us? */
-	pci_dev_for_each_resource(pdev, r) {
-		if (resource_type(r) != IORESOURCE_MEM)
-			continue;
-
-		if (!r->start || !r->end)
-			continue;
-
-		if (base < r->start || limit >= r->end)
-			continue;
-
-		return true;
-	}
-#endif
-	return false;
-}
-
 static bool vga_arb_integrated_gpu(struct device *dev)
 {
 #if defined(CONFIG_ACPI)
@@ -623,7 +591,7 @@ static bool vga_is_boot_device(struct vga_device *vgadev)
 	if (boot_vga && boot_vga->is_firmware_default)
 		return false;
 
-	if (vga_is_firmware_default(pdev)) {
+	if (video_is_primary_device(&pdev->dev)) {
 		vgadev->is_firmware_default = true;
 		return true;
 	}
-- 
2.43.0

[PATCH v4 8/8] PCI: Add a new 'boot_display' attribute

[Mario Limonciello]

From: Mario Limonciello <mario.limonciello@amd.com>

On systems with multiple GPUs there can be uncertainty which GPU is the
primary one used to drive the display at bootup. In order to disambiguate
this add a new sysfs attribute 'boot_display' that uses the output of
video_is_primary_device() to populate whether a PCI device was used for
driving the display.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
v4:
 * new patch
---
 Documentation/ABI/testing/sysfs-bus-pci |  9 +++++++++
 drivers/pci/pci-sysfs.c                 | 14 ++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index 69f952fffec72..2e6f85fbe2e2e 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -612,3 +612,12 @@ Description:
 
 		  # ls doe_features
 		  0001:01        0001:02        doe_discovery
+
+What:		/sys/bus/pci/devices/.../boot_display
+Date:		October 2025
+Contact:	Linux PCI developers <linux-pci@vger.kernel.org>
+Description:
+		This file indicates whether the device was used as a boot
+		display. If the device was used as the boot display, the file
+		will contain "1". If the device is a display device but wasn't
+		used as a boot display, the file will contain "0".
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 268c69daa4d57..5bbf79b1b953d 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -30,6 +30,7 @@
 #include <linux/msi.h>
 #include <linux/of.h>
 #include <linux/aperture.h>
+#include <asm/video.h>
 #include "pci.h"
 
 #ifndef ARCH_PCI_DEV_GROUPS
@@ -679,6 +680,13 @@ const struct attribute_group *pcibus_groups[] = {
 	NULL,
 };
 
+static ssize_t boot_display_show(struct device *dev, struct device_attribute *attr,
+				 char *buf)
+{
+	return sysfs_emit(buf, "%u\n", video_is_primary_device(dev));
+}
+static DEVICE_ATTR_RO(boot_display);
+
 static ssize_t boot_vga_show(struct device *dev, struct device_attribute *attr,
 			     char *buf)
 {
@@ -1698,6 +1706,7 @@ late_initcall(pci_sysfs_init);
 
 static struct attribute *pci_dev_dev_attrs[] = {
 	&dev_attr_boot_vga.attr,
+	&dev_attr_boot_display.attr,
 	NULL,
 };
 
@@ -1710,6 +1719,11 @@ static umode_t pci_dev_attrs_are_visible(struct kobject *kobj,
 	if (a == &dev_attr_boot_vga.attr && pci_is_vga(pdev))
 		return a->mode;
 
+#ifdef CONFIG_VIDEO
+	if (a == &dev_attr_boot_display.attr && pci_is_display(pdev))
+		return a->mode;
+#endif
+
 	return 0;
 }
 
-- 
2.43.0

Re: [PATCH v4 4/8] iommu/vt-d: Use pci_is_display()

[Baolu Lu]

On 6/24/25 02:47, Mario Limonciello wrote:
> From: Mario Limonciello<mario.limonciello@amd.com>
> 
> The inline pci_is_display() helper does the same thing.  Use it.
> 
> Reviewed-by: Daniel Dadap<ddadap@nvidia.com>
> Reviewed-by: Simona Vetter<simona.vetter@ffwll.ch>
> Suggested-by: Bjorn Helgaas<helgaas@kernel.org>
> Signed-off-by: Mario Limonciello<mario.limonciello@amd.com>

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>

Re: [PATCH v4 6/8] Fix access to video_is_primary_device() when compiled without CONFIG_VIDEO

[Thomas Zimmermann]

Am 23.06.25 um 20:47 schrieb Mario Limonciello:
> From: Mario Limonciello <mario.limonciello@amd.com>
>
> When compiled without CONFIG_VIDEO the architecture specific
> implementations of video_is_primary_device() include prototypes and
> assume that video-common.c will be linked. Guard against this so that the
> fallback inline implementation that returns false will be used when
> compiled without CONFIG_VIDEO.
>
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202506221312.49Fy1aNA-lkp@intel.com/
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>

Acked-by: Thomas Zimmermann <tzimmermann@suse.de>

> ---
> v4:
>   * new patch
> ---
>   arch/parisc/include/asm/video.h | 2 +-
>   arch/sparc/include/asm/video.h  | 2 ++
>   arch/x86/include/asm/video.h    | 2 ++
>   3 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/arch/parisc/include/asm/video.h b/arch/parisc/include/asm/video.h
> index c5dff3223194a..a9d50ebd6e769 100644
> --- a/arch/parisc/include/asm/video.h
> +++ b/arch/parisc/include/asm/video.h
> @@ -6,7 +6,7 @@
>   
>   struct device;
>   
> -#if defined(CONFIG_STI_CORE)
> +#if defined(CONFIG_STI_CORE) && defined(CONFIG_VIDEO)
>   bool video_is_primary_device(struct device *dev);
>   #define video_is_primary_device video_is_primary_device
>   #endif
> diff --git a/arch/sparc/include/asm/video.h b/arch/sparc/include/asm/video.h
> index a6f48f52db584..773717b6d4914 100644
> --- a/arch/sparc/include/asm/video.h
> +++ b/arch/sparc/include/asm/video.h
> @@ -19,8 +19,10 @@ static inline pgprot_t pgprot_framebuffer(pgprot_t prot,
>   #define pgprot_framebuffer pgprot_framebuffer
>   #endif
>   
> +#ifdef CONFIG_VIDEO
>   bool video_is_primary_device(struct device *dev);
>   #define video_is_primary_device video_is_primary_device
> +#endif
>   
>   static inline void fb_memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
>   {
> diff --git a/arch/x86/include/asm/video.h b/arch/x86/include/asm/video.h
> index 0950c9535fae9..08ec328203ef8 100644
> --- a/arch/x86/include/asm/video.h
> +++ b/arch/x86/include/asm/video.h
> @@ -13,8 +13,10 @@ pgprot_t pgprot_framebuffer(pgprot_t prot,
>   			    unsigned long offset);
>   #define pgprot_framebuffer pgprot_framebuffer
>   
> +#ifdef CONFIG_VIDEO
>   bool video_is_primary_device(struct device *dev);
>   #define video_is_primary_device video_is_primary_device
> +#endif
>   
>   #include <asm-generic/video.h>
>   

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

Re: [PATCH v4 7/8] PCI/VGA: Move check for firmware default out of VGA arbiter

[Thomas Zimmermann]

Am 23.06.25 um 20:47 schrieb Mario Limonciello:
> From: Mario Limonciello <mario.limonciello@amd.com>
>
> The x86 specific check for whether a framebuffer belongs to a device
> works for display devices as well as VGA devices.  Callers to
> video_is_primary_device() can benefit from checking non-VGA display
> devices.
>
> Move the x86 specific check into x86 specific code, and adjust VGA
> arbiter to call that code as well. This allows fbcon to find the
> right PCI device on systems that don't have VGA devices.
>
> Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
> v4:
>   * use helper
> ---
>   arch/x86/video/video-common.c | 13 ++++++++++++-
>   drivers/pci/vgaarb.c          | 36 ++---------------------------------
>   2 files changed, 14 insertions(+), 35 deletions(-)
>
> diff --git a/arch/x86/video/video-common.c b/arch/x86/video/video-common.c
> index 81fc97a2a837a..917568e4d7fb1 100644
> --- a/arch/x86/video/video-common.c
> +++ b/arch/x86/video/video-common.c
> @@ -9,6 +9,7 @@
>   
>   #include <linux/module.h>
>   #include <linux/pci.h>
> +#include <linux/screen_info.h>
>   #include <linux/vgaarb.h>
>   
>   #include <asm/video.h>
> @@ -27,6 +28,7 @@ EXPORT_SYMBOL(pgprot_framebuffer);
>   
>   bool video_is_primary_device(struct device *dev)
>   {
> +	struct screen_info *si = &screen_info;
>   	struct pci_dev *pdev;
>   
>   	if (!dev_is_pci(dev))
> @@ -34,7 +36,16 @@ bool video_is_primary_device(struct device *dev)
>   
>   	pdev = to_pci_dev(dev);
>   
> -	return (pdev == vga_default_device());
> +	if (!pci_is_display(pdev))
> +		return false;
> +
> +	if (pdev == vga_default_device())
> +		return true;
> +
> +	if (pdev == screen_info_pci_dev(si))
> +		return true;
> +
> +	return false;
>   }
>   EXPORT_SYMBOL(video_is_primary_device);
>   
> diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
> index 78748e8d2dbae..15ab58c70b016 100644
> --- a/drivers/pci/vgaarb.c
> +++ b/drivers/pci/vgaarb.c
> @@ -26,12 +26,12 @@
>   #include <linux/poll.h>
>   #include <linux/miscdevice.h>
>   #include <linux/slab.h>
> -#include <linux/screen_info.h>
>   #include <linux/vt.h>
>   #include <linux/console.h>
>   #include <linux/acpi.h>
>   #include <linux/uaccess.h>
>   #include <linux/vgaarb.h>
> +#include <asm/video.h>
>   
>   static void vga_arbiter_notify_clients(void);
>   
> @@ -554,38 +554,6 @@ void vga_put(struct pci_dev *pdev, unsigned int rsrc)
>   }
>   EXPORT_SYMBOL(vga_put);
>   
> -static bool vga_is_firmware_default(struct pci_dev *pdev)
> -{
> -#if defined(CONFIG_X86)
> -	u64 base = screen_info.lfb_base;
> -	u64 size = screen_info.lfb_size;
> -	struct resource *r;
> -	u64 limit;
> -
> -	/* Select the device owning the boot framebuffer if there is one */
> -
> -	if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
> -		base |= (u64)screen_info.ext_lfb_base << 32;
> -
> -	limit = base + size;
> -
> -	/* Does firmware framebuffer belong to us? */
> -	pci_dev_for_each_resource(pdev, r) {
> -		if (resource_type(r) != IORESOURCE_MEM)
> -			continue;
> -
> -		if (!r->start || !r->end)
> -			continue;
> -
> -		if (base < r->start || limit >= r->end)
> -			continue;
> -
> -		return true;
> -	}
> -#endif
> -	return false;
> -}
> -
>   static bool vga_arb_integrated_gpu(struct device *dev)
>   {
>   #if defined(CONFIG_ACPI)
> @@ -623,7 +591,7 @@ static bool vga_is_boot_device(struct vga_device *vgadev)
>   	if (boot_vga && boot_vga->is_firmware_default)
>   		return false;
>   
> -	if (vga_is_firmware_default(pdev)) {
> +	if (video_is_primary_device(&pdev->dev)) {

Doesn't this generate a cyclic dependency between vgaarb and video? I 
find this call cycle hard to reason about because 
vgaarb_default_device() depends on the results of these boot-device 
tests. Maybe keep vga_is_firmware_default() and just replace its content 
with a call to screen_info_pci_dev().
Best regards
Thomas

>   		vgadev->is_firmware_default = true;
>   		return true;
>   	}

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

Re: [PATCH v4 7/8] PCI/VGA: Move check for firmware default out of VGA arbiter

[Mario Limonciello]

On 6/24/25 4:21 AM, Thomas Zimmermann wrote:
> 
> 
> Am 23.06.25 um 20:47 schrieb Mario Limonciello:
>> From: Mario Limonciello <mario.limonciello@amd.com>
>>
>> The x86 specific check for whether a framebuffer belongs to a device
>> works for display devices as well as VGA devices.  Callers to
>> video_is_primary_device() can benefit from checking non-VGA display
>> devices.
>>
>> Move the x86 specific check into x86 specific code, and adjust VGA
>> arbiter to call that code as well. This allows fbcon to find the
>> right PCI device on systems that don't have VGA devices.
>>
>> Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
>> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
>> ---
>> v4:
>>   * use helper
>> ---
>>   arch/x86/video/video-common.c | 13 ++++++++++++-
>>   drivers/pci/vgaarb.c          | 36 ++---------------------------------
>>   2 files changed, 14 insertions(+), 35 deletions(-)
>>
>> diff --git a/arch/x86/video/video-common.c b/arch/x86/video/video- 
>> common.c
>> index 81fc97a2a837a..917568e4d7fb1 100644
>> --- a/arch/x86/video/video-common.c
>> +++ b/arch/x86/video/video-common.c
>> @@ -9,6 +9,7 @@
>>   #include <linux/module.h>
>>   #include <linux/pci.h>
>> +#include <linux/screen_info.h>
>>   #include <linux/vgaarb.h>
>>   #include <asm/video.h>
>> @@ -27,6 +28,7 @@ EXPORT_SYMBOL(pgprot_framebuffer);
>>   bool video_is_primary_device(struct device *dev)
>>   {
>> +    struct screen_info *si = &screen_info;
>>       struct pci_dev *pdev;
>>       if (!dev_is_pci(dev))
>> @@ -34,7 +36,16 @@ bool video_is_primary_device(struct device *dev)
>>       pdev = to_pci_dev(dev);
>> -    return (pdev == vga_default_device());
>> +    if (!pci_is_display(pdev))
>> +        return false;
>> +
>> +    if (pdev == vga_default_device())
>> +        return true;
>> +
>> +    if (pdev == screen_info_pci_dev(si))
>> +        return true;
>> +
>> +    return false;
>>   }
>>   EXPORT_SYMBOL(video_is_primary_device);
>> diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
>> index 78748e8d2dbae..15ab58c70b016 100644
>> --- a/drivers/pci/vgaarb.c
>> +++ b/drivers/pci/vgaarb.c
>> @@ -26,12 +26,12 @@
>>   #include <linux/poll.h>
>>   #include <linux/miscdevice.h>
>>   #include <linux/slab.h>
>> -#include <linux/screen_info.h>
>>   #include <linux/vt.h>
>>   #include <linux/console.h>
>>   #include <linux/acpi.h>
>>   #include <linux/uaccess.h>
>>   #include <linux/vgaarb.h>
>> +#include <asm/video.h>
>>   static void vga_arbiter_notify_clients(void);
>> @@ -554,38 +554,6 @@ void vga_put(struct pci_dev *pdev, unsigned int 
>> rsrc)
>>   }
>>   EXPORT_SYMBOL(vga_put);
>> -static bool vga_is_firmware_default(struct pci_dev *pdev)
>> -{
>> -#if defined(CONFIG_X86)
>> -    u64 base = screen_info.lfb_base;
>> -    u64 size = screen_info.lfb_size;
>> -    struct resource *r;
>> -    u64 limit;
>> -
>> -    /* Select the device owning the boot framebuffer if there is one */
>> -
>> -    if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
>> -        base |= (u64)screen_info.ext_lfb_base << 32;
>> -
>> -    limit = base + size;
>> -
>> -    /* Does firmware framebuffer belong to us? */
>> -    pci_dev_for_each_resource(pdev, r) {
>> -        if (resource_type(r) != IORESOURCE_MEM)
>> -            continue;
>> -
>> -        if (!r->start || !r->end)
>> -            continue;
>> -
>> -        if (base < r->start || limit >= r->end)
>> -            continue;
>> -
>> -        return true;
>> -    }
>> -#endif
>> -    return false;
>> -}
>> -
>>   static bool vga_arb_integrated_gpu(struct device *dev)
>>   {
>>   #if defined(CONFIG_ACPI)
>> @@ -623,7 +591,7 @@ static bool vga_is_boot_device(struct vga_device 
>> *vgadev)
>>       if (boot_vga && boot_vga->is_firmware_default)
>>           return false;
>> -    if (vga_is_firmware_default(pdev)) {
>> +    if (video_is_primary_device(&pdev->dev)) {
> 
> Doesn't this generate a cyclic dependency between vgaarb and video? I 
> find this call cycle hard to reason about because 
> vgaarb_default_device() depends on the results of these boot-device 
> tests. Maybe keep vga_is_firmware_default() and just replace its content 
> with a call to screen_info_pci_dev().
> Best regards
> Thomas

OK, I'll do that, thanks.

> 
>>           vgadev->is_firmware_default = true;
>>           return true;
>>       }
>