Commit f8d81df2 authored by Huacai Chen's avatar Huacai Chen Committed by Bjorn Helgaas
Browse files

PCI/VGA: Move firmware default device detection to ADD_DEVICE path 

Previously we selected the firmware default device, i.e., one that owns the
boot framebuffer, as the default device in vga_arb_select_default_device().
This was only done in the vga_arb_device_init() subsys_initcall, so devices
enumerated later, e.g., by pcibios_init(), were not eligible.

Fix this by moving the firmware default device selection from
vga_arb_select_default_device() to vga_arbiter_add_pci_device(), which is
called after every PCI device is enumerated, either by the
vga_arb_device_init() subsys_initcall or as an ADD_DEVICE notifier.

Note that if vga_arb_select_default_device() previously found a device
owning the boot framebuffer, it unconditionally set it to be the default
VGA device, and no subsequent device could replace it.

[bhelgaas: commit log, restructure slightly]
Link: https://lore.kernel.org/r/20211015061512.2941859-7-chenhuacai@loongson.cn
Link: https://lore.kernel.org/r/20220224224753.297579-6-helgaas@kernel.org


Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Cc: Bruno Prémont <bonbons@linux-vserver.org>
parent dfe3da81

drivers/pci/vgaarb.c

+17 −20
Original line number Diff line number Diff line
@@ -72,6 +72,7 @@ struct vga_device { 
	unsigned int io_norm_cnt;	/* normal IO count */

	unsigned int mem_norm_cnt;	/* normal MEM count */

	bool bridge_has_one_vga;

	bool is_firmware_default;	/* device selected by firmware */

	unsigned int (*set_decode)(struct pci_dev *pdev, bool decode);

};
@@ -565,10 +566,9 @@ void vga_put(struct pci_dev *pdev, unsigned int rsrc) 
}

EXPORT_SYMBOL(vga_put);



static void __init vga_select_framebuffer_device(struct pci_dev *pdev)

static bool vga_is_firmware_default(struct pci_dev *pdev)

{

#if defined(CONFIG_X86) || defined(CONFIG_IA64)

	struct device *dev = &pdev->dev;

	u64 base = screen_info.lfb_base;

	u64 size = screen_info.lfb_size;

	u64 limit;
@@ -583,15 +583,6 @@ static void __init vga_select_framebuffer_device(struct pci_dev *pdev) 


	limit = base + size;



	/*

	 * Override vga_arbiter_add_pci_device()'s I/O based detection

	 * as it may take the wrong device (e.g. on Apple system under

	 * EFI).

	 *

	 * Select the device owning the boot framebuffer if there is

	 * one.

	 */



	/* Does firmware framebuffer belong to us? */

	for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {

		flags = pci_resource_flags(pdev, i);
@@ -608,13 +599,10 @@ static void __init vga_select_framebuffer_device(struct pci_dev *pdev) 
		if (base < start || limit >= end)

			continue;



		if (!vga_default_device())

			vgaarb_info(dev, "setting as boot device\n");

		else if (pdev != vga_default_device())

			vgaarb_info(dev, "overriding boot device\n");

		vga_set_default_device(pdev);

		return true;

	}

#endif

	return false;

}



static bool vga_arb_integrated_gpu(struct device *dev)
@@ -635,6 +623,7 @@ static bool vga_arb_integrated_gpu(struct device *dev) 
static bool vga_is_boot_device(struct vga_device *vgadev)

{

	struct vga_device *boot_vga = vgadev_find(vga_default_device());

	struct pci_dev *pdev = vgadev->pdev;



	/*

	 * We select the default VGA device in this order:
@@ -645,6 +634,18 @@ static bool vga_is_boot_device(struct vga_device *vgadev) 
	 *   Other device (see vga_arb_select_default_device())

	 */



	/*

	 * We always prefer a firmware default device, so if we've already

	 * found one, there's no need to consider vgadev.

	 */

	if (boot_vga && boot_vga->is_firmware_default)

		return false;



	if (vga_is_firmware_default(pdev)) {

		vgadev->is_firmware_default = true;

		return true;

	}



	/*

	 * A legacy VGA device has MEM and IO enabled and any bridges

	 * leading to it have PCI_BRIDGE_CTL_VGA enabled so the legacy
@@ -1531,10 +1532,6 @@ static void __init vga_arb_select_default_device(void) 
	struct pci_dev *pdev, *found = NULL;

	struct vga_device *vgadev;



	list_for_each_entry(vgadev, &vga_list, list) {

		vga_select_framebuffer_device(vgadev->pdev);

	}



	if (!vga_default_device()) {

		list_for_each_entry_reverse(vgadev, &vga_list, list) {

			struct device *dev = &vgadev->pdev->dev;