[PATCH] vgaarb: Rework default VGA device selection
Huacai Chen
chenhuacai at kernel.org
Tue Jul 6 09:21:42 UTC 2021
Hi, Daniel,
On Tue, Jul 6, 2021 at 4:21 PM Daniel Vetter <daniel at ffwll.ch> wrote:
>
> On Mon, Jul 05, 2021 at 06:05:03PM +0800, Huacai Chen 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 at loongson.cn>
>
> Sounds reasonable, but because this is defacto pci stuff that just isn't
> in drivers/pci (maybe we should move it) I'll defer to Bjorn's review
> before I apply this patch.
> -Daniel
This (move to drivers/pci) has been disscussed before, I think that
can be another patch.
Huacai
>
> > ---
> > 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");
> > + else
> > + vgaarb_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");
> > + else
> > + vgaarb_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");
> > - else
> > - vgaarb_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
> >
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
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