diff mbox series

[v8,04/10] vgaarb: Move framebuffer detection to ADD_DEVICE path

Message ID 20220106000658.243509-5-helgaas@kernel.org (mailing list archive)
State New, archived
Headers show
Series vgaarb: Rework default VGA device selection | expand

Commit Message

Bjorn Helgaas Jan. 6, 2022, 12:06 a.m. UTC
From: Bjorn Helgaas <bhelgaas@google.com>

Previously we selected a device 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 framebuffer 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() found a device owning the boot
framebuffer, it unconditionally set it to be the default VGA device, and no
subsequent device could replace it.

Link: https://lore.kernel.org/r/20211015061512.2941859-7-chenhuacai@loongson.cn
Based-on-patch-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Bruno Prémont <bonbons@linux-vserver.org>
---
 drivers/gpu/vga/vgaarb.c | 37 +++++++++++++++++--------------------
 1 file changed, 17 insertions(+), 20 deletions(-)

Comments

Huacai Chen Jan. 6, 2022, 6:44 a.m. UTC | #1
Hi, Bjorn,

On Thu, Jan 6, 2022 at 8:07 AM Bjorn Helgaas <helgaas@kernel.org> wrote:
>
> From: Bjorn Helgaas <bhelgaas@google.com>
>
> Previously we selected a device 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 framebuffer 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() found a device owning the boot
> framebuffer, it unconditionally set it to be the default VGA device, and no
> subsequent device could replace it.
>
> Link: https://lore.kernel.org/r/20211015061512.2941859-7-chenhuacai@loongson.cn
> Based-on-patch-by: Huacai Chen <chenhuacai@loongson.cn>
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> Cc: Bruno Prémont <bonbons@linux-vserver.org>
> ---
>  drivers/gpu/vga/vgaarb.c | 37 +++++++++++++++++--------------------
>  1 file changed, 17 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
> index b0ae0f177c6f..aefa4f406f7d 100644
> --- a/drivers/gpu/vga/vgaarb.c
> +++ b/drivers/gpu/vga/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_framebuffer;    /* BAR covers firmware framebuffer */
>         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_framebuffer_device(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 framebuffer, so if we've already
> +        * found one, there's no need to consider vgadev.
> +        */
> +       if (boot_vga && boot_vga->is_framebuffer)
> +               return false;
> +
> +       if (vga_is_framebuffer_device(pdev)) {
> +               vgadev->is_framebuffer = true;
> +               return true;
> +       }
Maybe it is better to rename vga_is_framebuffer_device() to
vga_is_firmware_device() and rename is_framebuffer to
is_fw_framebuffer?

Huacai
> +
>         /*
>          * 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;
> --
> 2.25.1
>
Bjorn Helgaas Jan. 6, 2022, 4:20 p.m. UTC | #2
On Thu, Jan 06, 2022 at 02:44:42PM +0800, Huacai Chen wrote:
> On Thu, Jan 6, 2022 at 8:07 AM Bjorn Helgaas <helgaas@kernel.org> wrote:
> > Previously we selected a device 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 framebuffer 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() found a device owning the boot
> > framebuffer, it unconditionally set it to be the default VGA device, and no
> > subsequent device could replace it.
> >
> > Link: https://lore.kernel.org/r/20211015061512.2941859-7-chenhuacai@loongson.cn
> > Based-on-patch-by: Huacai Chen <chenhuacai@loongson.cn>
> > Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> > Cc: Bruno Prémont <bonbons@linux-vserver.org>
> > ---
> >  drivers/gpu/vga/vgaarb.c | 37 +++++++++++++++++--------------------
> >  1 file changed, 17 insertions(+), 20 deletions(-)
> >
> > diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
> > index b0ae0f177c6f..aefa4f406f7d 100644
> > --- a/drivers/gpu/vga/vgaarb.c
> > +++ b/drivers/gpu/vga/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_framebuffer;    /* BAR covers firmware framebuffer */
> >         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_framebuffer_device(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 framebuffer, so if we've already
> > +        * found one, there's no need to consider vgadev.
> > +        */
> > +       if (boot_vga && boot_vga->is_framebuffer)
> > +               return false;
> > +
> > +       if (vga_is_framebuffer_device(pdev)) {
> > +               vgadev->is_framebuffer = true;
> > +               return true;
> > +       }
> Maybe it is better to rename vga_is_framebuffer_device() to
> vga_is_firmware_device() and rename is_framebuffer to
> is_fw_framebuffer?

That's a great point, thanks!

The "framebuffer" term is way too generic.  *All* VGA devices have a
framebuffer, so it adds no information.  This is really about finding
the device that was used by firmware.

I renamed:

  vga_is_framebuffer_device() -> vga_is_firmware_default()
  vga_device.is_framebuffer   -> vga_device.is_firmware_default

I updated my local branch and pushed it to:
https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git/log/?h=pci/vga
with head 0f4caffa1297 ("vgaarb: Replace full MIT license text with
SPDX identifier").

I don't maintain drivers/gpu/vga/vgaarb.c, so this branch is just for
reference.  It'll ultimately be up to the DRM folks to handle this.

I'll wait for any other comments or testing reports before reposting.

> >         /*
> >          * 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;
> > --
> > 2.25.1
> >
Huacai Chen Jan. 25, 2022, 2:51 a.m. UTC | #3
Hi, Bjorn,

Why this series still missing in 5.17-rc1? :(

Huacai

On Fri, Jan 7, 2022 at 12:21 AM Bjorn Helgaas <helgaas@kernel.org> wrote:
>
> On Thu, Jan 06, 2022 at 02:44:42PM +0800, Huacai Chen wrote:
> > On Thu, Jan 6, 2022 at 8:07 AM Bjorn Helgaas <helgaas@kernel.org> wrote:
> > > Previously we selected a device 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 framebuffer 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() found a device owning the boot
> > > framebuffer, it unconditionally set it to be the default VGA device, and no
> > > subsequent device could replace it.
> > >
> > > Link: https://lore.kernel.org/r/20211015061512.2941859-7-chenhuacai@loongson.cn
> > > Based-on-patch-by: Huacai Chen <chenhuacai@loongson.cn>
> > > Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> > > Cc: Bruno Prémont <bonbons@linux-vserver.org>
> > > ---
> > >  drivers/gpu/vga/vgaarb.c | 37 +++++++++++++++++--------------------
> > >  1 file changed, 17 insertions(+), 20 deletions(-)
> > >
> > > diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
> > > index b0ae0f177c6f..aefa4f406f7d 100644
> > > --- a/drivers/gpu/vga/vgaarb.c
> > > +++ b/drivers/gpu/vga/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_framebuffer;    /* BAR covers firmware framebuffer */
> > >         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_framebuffer_device(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 framebuffer, so if we've already
> > > +        * found one, there's no need to consider vgadev.
> > > +        */
> > > +       if (boot_vga && boot_vga->is_framebuffer)
> > > +               return false;
> > > +
> > > +       if (vga_is_framebuffer_device(pdev)) {
> > > +               vgadev->is_framebuffer = true;
> > > +               return true;
> > > +       }
> > Maybe it is better to rename vga_is_framebuffer_device() to
> > vga_is_firmware_device() and rename is_framebuffer to
> > is_fw_framebuffer?
>
> That's a great point, thanks!
>
> The "framebuffer" term is way too generic.  *All* VGA devices have a
> framebuffer, so it adds no information.  This is really about finding
> the device that was used by firmware.
>
> I renamed:
>
>   vga_is_framebuffer_device() -> vga_is_firmware_default()
>   vga_device.is_framebuffer   -> vga_device.is_firmware_default
>
> I updated my local branch and pushed it to:
> https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git/log/?h=pci/vga
> with head 0f4caffa1297 ("vgaarb: Replace full MIT license text with
> SPDX identifier").
>
> I don't maintain drivers/gpu/vga/vgaarb.c, so this branch is just for
> reference.  It'll ultimately be up to the DRM folks to handle this.
>
> I'll wait for any other comments or testing reports before reposting.
>
> > >         /*
> > >          * 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;
> > > --
> > > 2.25.1
> > >
Bjorn Helgaas Jan. 25, 2022, 3:38 p.m. UTC | #4
[+cc Maarten, Maxime, Thomas; beginning of thread:
https://lore.kernel.org/r/20220106000658.243509-1-helgaas@kernel.org]

On Tue, Jan 25, 2022 at 10:51:15AM +0800, Huacai Chen wrote:
> Hi, Bjorn,
> 
> Why this series still missing in 5.17-rc1? :(

1) It was posted late in the cycle (Jan 6, when the merge window
opened Jan 9), so it was too late to expect a significant change like
this to be merged for v5.17.  Right now is a good time to consider it
again so it would some time in -next.

2) As of now, this code is still in drivers/gpu, and I don't maintain
that area.  It's up to the DRM folks, who are all cc'd here.

I would like to move this from drivers/gpu to drivers/pci, but that
requires a little more work to resolve the initcall ordering problem
with respect to vga_arb_device_init() and misc_init() [1].

Bjorn

[1] https://lore.kernel.org/linux-pci/CAAhV-H7FhAjM-Ha42Z1dLrE4PvC9frfyeU27KHWcyWKkMftEsA@mail.gmail.com/

> On Fri, Jan 7, 2022 at 12:21 AM Bjorn Helgaas <helgaas@kernel.org> wrote:
> >
> > On Thu, Jan 06, 2022 at 02:44:42PM +0800, Huacai Chen wrote:
> > > On Thu, Jan 6, 2022 at 8:07 AM Bjorn Helgaas <helgaas@kernel.org> wrote:
> > > > Previously we selected a device 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 framebuffer 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() found a device owning the boot
> > > > framebuffer, it unconditionally set it to be the default VGA device, and no
> > > > subsequent device could replace it.
> > > >
> > > > Link: https://lore.kernel.org/r/20211015061512.2941859-7-chenhuacai@loongson.cn
> > > > Based-on-patch-by: Huacai Chen <chenhuacai@loongson.cn>
> > > > Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> > > > Cc: Bruno Prémont <bonbons@linux-vserver.org>
> > > > ---
> > > >  drivers/gpu/vga/vgaarb.c | 37 +++++++++++++++++--------------------
> > > >  1 file changed, 17 insertions(+), 20 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
> > > > index b0ae0f177c6f..aefa4f406f7d 100644
> > > > --- a/drivers/gpu/vga/vgaarb.c
> > > > +++ b/drivers/gpu/vga/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_framebuffer;    /* BAR covers firmware framebuffer */
> > > >         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_framebuffer_device(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 framebuffer, so if we've already
> > > > +        * found one, there's no need to consider vgadev.
> > > > +        */
> > > > +       if (boot_vga && boot_vga->is_framebuffer)
> > > > +               return false;
> > > > +
> > > > +       if (vga_is_framebuffer_device(pdev)) {
> > > > +               vgadev->is_framebuffer = true;
> > > > +               return true;
> > > > +       }
> > > Maybe it is better to rename vga_is_framebuffer_device() to
> > > vga_is_firmware_device() and rename is_framebuffer to
> > > is_fw_framebuffer?
> >
> > That's a great point, thanks!
> >
> > The "framebuffer" term is way too generic.  *All* VGA devices have a
> > framebuffer, so it adds no information.  This is really about finding
> > the device that was used by firmware.
> >
> > I renamed:
> >
> >   vga_is_framebuffer_device() -> vga_is_firmware_default()
> >   vga_device.is_framebuffer   -> vga_device.is_firmware_default
> >
> > I updated my local branch and pushed it to:
> > https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git/log/?h=pci/vga
> > with head 0f4caffa1297 ("vgaarb: Replace full MIT license text with
> > SPDX identifier").
> >
> > I don't maintain drivers/gpu/vga/vgaarb.c, so this branch is just for
> > reference.  It'll ultimately be up to the DRM folks to handle this.
> >
> > I'll wait for any other comments or testing reports before reposting.
> >
> > > >         /*
> > > >          * 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;
> > > > --
> > > > 2.25.1
> > > >
Huacai Chen Jan. 26, 2022, 2:25 a.m. UTC | #5
On Tue, Jan 25, 2022 at 11:39 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
>
> [+cc Maarten, Maxime, Thomas; beginning of thread:
> https://lore.kernel.org/r/20220106000658.243509-1-helgaas@kernel.org]
>
> On Tue, Jan 25, 2022 at 10:51:15AM +0800, Huacai Chen wrote:
> > Hi, Bjorn,
> >
> > Why this series still missing in 5.17-rc1? :(
>
> 1) It was posted late in the cycle (Jan 6, when the merge window
> opened Jan 9), so it was too late to expect a significant change like
> this to be merged for v5.17.  Right now is a good time to consider it
> again so it would some time in -next.
>
> 2) As of now, this code is still in drivers/gpu, and I don't maintain
> that area.  It's up to the DRM folks, who are all cc'd here.
>
> I would like to move this from drivers/gpu to drivers/pci, but that
> requires a little more work to resolve the initcall ordering problem
> with respect to vga_arb_device_init() and misc_init() [1].
Hmm, to me, keep it in drivers/gpu is just OK.

Huacai

>
> Bjorn
>
> [1] https://lore.kernel.org/linux-pci/CAAhV-H7FhAjM-Ha42Z1dLrE4PvC9frfyeU27KHWcyWKkMftEsA@mail.gmail.com/
>
> > On Fri, Jan 7, 2022 at 12:21 AM Bjorn Helgaas <helgaas@kernel.org> wrote:
> > >
> > > On Thu, Jan 06, 2022 at 02:44:42PM +0800, Huacai Chen wrote:
> > > > On Thu, Jan 6, 2022 at 8:07 AM Bjorn Helgaas <helgaas@kernel.org> wrote:
> > > > > Previously we selected a device 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 framebuffer 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() found a device owning the boot
> > > > > framebuffer, it unconditionally set it to be the default VGA device, and no
> > > > > subsequent device could replace it.
> > > > >
> > > > > Link: https://lore.kernel.org/r/20211015061512.2941859-7-chenhuacai@loongson.cn
> > > > > Based-on-patch-by: Huacai Chen <chenhuacai@loongson.cn>
> > > > > Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> > > > > Cc: Bruno Prémont <bonbons@linux-vserver.org>
> > > > > ---
> > > > >  drivers/gpu/vga/vgaarb.c | 37 +++++++++++++++++--------------------
> > > > >  1 file changed, 17 insertions(+), 20 deletions(-)
> > > > >
> > > > > diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
> > > > > index b0ae0f177c6f..aefa4f406f7d 100644
> > > > > --- a/drivers/gpu/vga/vgaarb.c
> > > > > +++ b/drivers/gpu/vga/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_framebuffer;    /* BAR covers firmware framebuffer */
> > > > >         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_framebuffer_device(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 framebuffer, so if we've already
> > > > > +        * found one, there's no need to consider vgadev.
> > > > > +        */
> > > > > +       if (boot_vga && boot_vga->is_framebuffer)
> > > > > +               return false;
> > > > > +
> > > > > +       if (vga_is_framebuffer_device(pdev)) {
> > > > > +               vgadev->is_framebuffer = true;
> > > > > +               return true;
> > > > > +       }
> > > > Maybe it is better to rename vga_is_framebuffer_device() to
> > > > vga_is_firmware_device() and rename is_framebuffer to
> > > > is_fw_framebuffer?
> > >
> > > That's a great point, thanks!
> > >
> > > The "framebuffer" term is way too generic.  *All* VGA devices have a
> > > framebuffer, so it adds no information.  This is really about finding
> > > the device that was used by firmware.
> > >
> > > I renamed:
> > >
> > >   vga_is_framebuffer_device() -> vga_is_firmware_default()
> > >   vga_device.is_framebuffer   -> vga_device.is_firmware_default
> > >
> > > I updated my local branch and pushed it to:
> > > https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git/log/?h=pci/vga
> > > with head 0f4caffa1297 ("vgaarb: Replace full MIT license text with
> > > SPDX identifier").
> > >
> > > I don't maintain drivers/gpu/vga/vgaarb.c, so this branch is just for
> > > reference.  It'll ultimately be up to the DRM folks to handle this.
> > >
> > > I'll wait for any other comments or testing reports before reposting.
> > >
> > > > >         /*
> > > > >          * 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;
> > > > > --
> > > > > 2.25.1
> > > > >
diff mbox series

Patch

diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
index b0ae0f177c6f..aefa4f406f7d 100644
--- a/drivers/gpu/vga/vgaarb.c
+++ b/drivers/gpu/vga/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_framebuffer;	/* BAR covers firmware framebuffer */
 	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_framebuffer_device(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 framebuffer, so if we've already
+	 * found one, there's no need to consider vgadev.
+	 */
+	if (boot_vga && boot_vga->is_framebuffer)
+		return false;
+
+	if (vga_is_framebuffer_device(pdev)) {
+		vgadev->is_framebuffer = 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;