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: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Bruno Prémont <bonbons@linux-vserver.org>

diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
index 58e0a12..c3323ab 100644 (file)
--- a/drivers/pci/vgaarb.c
+++ b/drivers/pci/vgaarb.c
@@ -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 @@ bail:
 }
 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:
@@ -646,6 +635,18 @@ static bool vga_is_boot_device(struct vga_device *vgadev)
         */
 
        /*
+        * 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
         * resources ([mem 0xa0000-0xbffff], [io 0x3b0-0x3bb], etc) are
@@ -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;