[+cc linux-pci]
On Mon, Jul 5, 2021 at 5:04 AM Huacai Chen chenhuacai@loongson.cn wrote:
Currently, vga_arb_device_init() selects the first probed VGA device with VGA legacy resources enabled as the default device. However, some BMC-based VGA cards (e.g., AST2500 and HiSilicon D05) don't enable VGA legacy resources because their built-in upstream bridges don't support PCI_BRIDGE_CTL_VGA. This makes "no default VGA card" and breaks X.org auto-detection.
Commit a37c0f48950b56f6ef2e ("vgaarb: Select a default VGA device even if there's no legacy VGA") try to solve this problem but fails on some platforms, because it relies on the initcall order:
We should call vga_arb_device_init() after PCI enumeration, otherwise it may fail to select the default VGA device. Since vga_arb_device_init() and PCI enumeration function (i.e., pcibios_init() or acpi_init()) are both wrapped by subsys_initcall(), their sequence is not assured. So, it is possible to use subsys_initcall_sync() instead of subsys_initcall() to wrap vga_arb_device_init().
However, the above approach still has drawbacks, it cannot handle the cases that a VGA card is hot-plugged, or the gpu driver is compiled as a module.
So, as suggested by Bjorn Helgaas, this patch rework the selection: 1, Remove direct vga_arb_select_default_device() calls in vga_arb_ device_init(). 2, Rename vga_arb_select_default_device() to vga_arb_update_default_ device(), which selects the first probed VGA device as the default (whether legacy resources enabled or not), and update the default device if a better one is found (device with legacy resources enabled is better, device owns the firmware framebuffer is even better). 3, Every time a new VGA device is probed, vga_arbiter_add_pci_device() is called, and vga_arb_update_default_device() is also called. So the hotplug case and the module case can also be handled.
Signed-off-by: Huacai Chen chenhuacai@loongson.cn
drivers/gpu/vga/vgaarb.c | 219 +++++++++++++++++---------------------- 1 file changed, 97 insertions(+), 122 deletions(-)
diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c index 949fde433ea2..07770aae3aaf 100644 --- a/drivers/gpu/vga/vgaarb.c +++ b/drivers/gpu/vga/vgaarb.c @@ -586,6 +586,97 @@ void vga_put(struct pci_dev *pdev, unsigned int rsrc) } EXPORT_SYMBOL(vga_put);
+#if defined(CONFIG_ACPI) +static bool vga_arb_integrated_gpu(struct device *dev) +{
struct acpi_device *adev = ACPI_COMPANION(dev);return adev && !strcmp(acpi_device_hid(adev), ACPI_VIDEO_HID);+} +#else +static bool vga_arb_integrated_gpu(struct device *dev) +{
return false;+} +#endif
+static void vga_arb_update_default_device(struct vga_device *vgadev) +{
struct pci_dev *pdev = vgadev->pdev;struct device *dev = &pdev->dev;struct vga_device *vgadev_default;+#if defined(CONFIG_X86) || defined(CONFIG_IA64)
int i;unsigned long flags;u64 base = screen_info.lfb_base;u64 size = screen_info.lfb_size;u64 limit;resource_size_t start, end;+#endif
/* Deal with VGA default device. Use first enabled one* by default if arch doesn't have it's own hook*/if (!vga_default_device()) {if ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)vgaarb_info(dev, "setting as boot VGA device\n");elsevgaarb_info(dev, "setting as boot device (VGA legacy resources not available)\n");vga_set_default_device(pdev);}vgadev_default = vgadev_find(vga_default);/* Overridden by a better device */if (vgadev_default && ((vgadev_default->owns & VGA_RSRC_LEGACY_MASK) == 0)&& ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)) {vgaarb_info(dev, "overriding boot VGA device\n");vga_set_default_device(pdev);}if (vga_arb_integrated_gpu(dev)) {vgaarb_info(dev, "overriding boot VGA device\n");vga_set_default_device(pdev);}+#if defined(CONFIG_X86) || defined(CONFIG_IA64)
if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)base |= (u64)screen_info.ext_lfb_base << 32;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(vgadev->pdev, i);if ((flags & IORESOURCE_MEM) == 0)continue;start = pci_resource_start(vgadev->pdev, i);end = pci_resource_end(vgadev->pdev, i);if (!start || !end)continue;if (base < start || limit >= end)continue;if (vgadev->pdev != vga_default_device())vgaarb_info(dev, "overriding boot device\n");vga_set_default_device(vgadev->pdev);}+#endif +}
/*
- Rules for using a bridge to control a VGA descendant decoding: if a bridge
- has only one VGA descendant then it can be used to control the VGA routing
@@ -643,6 +734,11 @@ static void vga_arbiter_check_bridge_sharing(struct vga_device *vgadev) } new_bus = new_bus->parent; }
if (vgadev->bridge_has_one_vga == true)vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");elsevgaarb_info(&vgadev->pdev->dev, "no bridge control possible\n");}
/* @@ -713,15 +809,7 @@ static bool vga_arbiter_add_pci_device(struct pci_dev *pdev) bus = bus->parent; }
/* Deal with VGA default device. Use first enabled one* by default if arch doesn't have it's own hook*/if (vga_default == NULL &&((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)) {vgaarb_info(&pdev->dev, "setting as boot VGA device\n");vga_set_default_device(pdev);}
vga_arb_update_default_device(vgadev); vga_arbiter_check_bridge_sharing(vgadev); /* Add to the list */@@ -1451,111 +1539,10 @@ static struct miscdevice vga_arb_device = { MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops };
-#if defined(CONFIG_ACPI) -static bool vga_arb_integrated_gpu(struct device *dev) -{
struct acpi_device *adev = ACPI_COMPANION(dev);return adev && !strcmp(acpi_device_hid(adev), ACPI_VIDEO_HID);-} -#else -static bool vga_arb_integrated_gpu(struct device *dev) -{
return false;-} -#endif
-static void __init vga_arb_select_default_device(void) -{
struct pci_dev *pdev, *found = NULL;struct vga_device *vgadev;-#if defined(CONFIG_X86) || defined(CONFIG_IA64)
u64 base = screen_info.lfb_base;u64 size = screen_info.lfb_size;u64 limit;resource_size_t start, end;unsigned long flags;int i;if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)base |= (u64)screen_info.ext_lfb_base << 32;limit = base + size;list_for_each_entry(vgadev, &vga_list, list) {struct device *dev = &vgadev->pdev->dev;/** 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(vgadev->pdev, i);if ((flags & IORESOURCE_MEM) == 0)continue;start = pci_resource_start(vgadev->pdev, i);end = pci_resource_end(vgadev->pdev, i);if (!start || !end)continue;if (base < start || limit >= end)continue;if (!vga_default_device())vgaarb_info(dev, "setting as boot device\n");else if (vgadev->pdev != vga_default_device())vgaarb_info(dev, "overriding boot device\n");vga_set_default_device(vgadev->pdev);}}-#endif
if (!vga_default_device()) {list_for_each_entry_reverse(vgadev, &vga_list, list) {struct device *dev = &vgadev->pdev->dev;u16 cmd;pdev = vgadev->pdev;pci_read_config_word(pdev, PCI_COMMAND, &cmd);if (cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {found = pdev;if (vga_arb_integrated_gpu(dev))break;}}}if (found) {vgaarb_info(&found->dev, "setting as boot device (VGA legacy resources not available)\n");vga_set_default_device(found);return;}if (!vga_default_device()) {vgadev = list_first_entry_or_null(&vga_list,struct vga_device, list);if (vgadev) {struct device *dev = &vgadev->pdev->dev;vgaarb_info(dev, "setting as boot device (VGA legacy resources not available)\n");vga_set_default_device(vgadev->pdev);}}-}
static int __init vga_arb_device_init(void) { int rc; struct pci_dev *pdev;
struct vga_device *vgadev; rc = misc_register(&vga_arb_device); if (rc < 0)@@ -1571,18 +1558,6 @@ static int __init vga_arb_device_init(void) PCI_ANY_ID, pdev)) != NULL) vga_arbiter_add_pci_device(pdev);
list_for_each_entry(vgadev, &vga_list, list) {struct device *dev = &vgadev->pdev->dev;if (vgadev->bridge_has_one_vga)vgaarb_info(dev, "bridge control possible\n");elsevgaarb_info(dev, "no bridge control possible\n");}vga_arb_select_default_device();pr_info("loaded\n"); return rc;} subsys_initcall(vga_arb_device_init); -- 2.27.0