[v2,2/2] vgaarb: Factor out EFI and fallback default device selection

Message ID 20171013034729.14630.30419.stgit@bhelgaas-glaptop.roam.corp.google.com
State Not Applicable
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Series
  • vgaarb: Select fallback default VGA device
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Commit Message

Bjorn Helgaas Oct. 13, 2017, 3:47 a.m.
The default VGA device is normally set in vga_arbiter_add_pci_device() when
we call it for the first enabled device that can be accessed with the
legacy VGA resources ([mem 0xa0000-0xbffff], etc.)

That default device can be overridden by an EFI device that owns the boot
framebuffer.  As a fallback, we can also select a VGA device that can't be
accessed via legacy VGA resources, or a VGA device that isn't even enabled.

Factor out this EFI and fallback selection from vga_arb_device_init() into
a separate vga_arb_select_default_device() function.  This doesn't change
any behavior, but it untangles the "bridge control possible" checking and
messages from the default device selection.

Tested-by: Zhou Wang <wangzhou1@hisilicon.com>  # D05 Hisi Hip07, Hip08
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/gpu/vga/vgaarb.c |   57 ++++++++++++++++++++++++++++------------------
 1 file changed, 35 insertions(+), 22 deletions(-)

Comments

Daniel Axtens Oct. 17, 2017, 2:03 a.m. | #1
Bjorn Helgaas <bhelgaas@google.com> writes:

> The default VGA device is normally set in vga_arbiter_add_pci_device() when
> we call it for the first enabled device that can be accessed with the
> legacy VGA resources ([mem 0xa0000-0xbffff], etc.)
>
> That default device can be overridden by an EFI device that owns the boot
> framebuffer.  As a fallback, we can also select a VGA device that can't be
> accessed via legacy VGA resources, or a VGA device that isn't even enabled.
>
> Factor out this EFI and fallback selection from vga_arb_device_init() into
> a separate vga_arb_select_default_device() function.  This doesn't change
> any behavior, but it untangles the "bridge control possible" checking and
> messages from the default device selection.
>
> Tested-by: Zhou Wang <wangzhou1@hisilicon.com>  # D05 Hisi Hip07, Hip08
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
>  drivers/gpu/vga/vgaarb.c |   57 ++++++++++++++++++++++++++++------------------
>  1 file changed, 35 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
> index 8035e38d5110..d35d6d271f3f 100644
> --- a/drivers/gpu/vga/vgaarb.c
> +++ b/drivers/gpu/vga/vgaarb.c
> @@ -1402,29 +1402,14 @@ static struct miscdevice vga_arb_device = {
>  	MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
>  };
>  
> -static int __init vga_arb_device_init(void)
> +static void __init vga_arb_select_default_device(void)
>  {
> -	int rc;
>  	struct pci_dev *pdev;
>  	struct vga_device *vgadev;
>  
> -	rc = misc_register(&vga_arb_device);
> -	if (rc < 0)
> -		pr_err("error %d registering device\n", rc);
> -
> -	bus_register_notifier(&pci_bus_type, &pci_notifier);
> -
> -	/* We add all pci devices satisfying vga class in the arbiter by
> -	 * default */
> -	pdev = NULL;
> -	while ((pdev =
> -		pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
> -			       PCI_ANY_ID, pdev)) != NULL)
> -		vga_arbiter_add_pci_device(pdev);
> -
> +#if defined(CONFIG_X86) || defined(CONFIG_IA64)
>  	list_for_each_entry(vgadev, &vga_list, list) {
>  		struct device *dev = &vgadev->pdev->dev;
> -#if defined(CONFIG_X86) || defined(CONFIG_IA64)
>  		/*
>  		 * Override vga_arbiter_add_pci_device()'s I/O based detection
>  		 * as it may take the wrong device (e.g. on Apple system under
> @@ -1461,12 +1446,8 @@ static int __init vga_arb_device_init(void)
>  				vgaarb_info(dev, "overriding boot device\n");
>  			vga_set_default_device(vgadev->pdev);
>  		}
> -#endif
> -		if (vgadev->bridge_has_one_vga)
> -			vgaarb_info(dev, "bridge control possible\n");
> -		else
> -			vgaarb_info(dev, "no bridge control possible\n");
>  	}
> +#endif
>  
>  	if (!vga_default_device()) {
>  		list_for_each_entry(vgadev, &vga_list, list) {
> @@ -1492,6 +1473,38 @@ static int __init vga_arb_device_init(void)
>  			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)
> +		pr_err("error %d registering device\n", rc);
> +
> +	bus_register_notifier(&pci_bus_type, &pci_notifier);
> +
> +	/* We add all PCI devices satisfying VGA class in the arbiter by
> +	 * default */
> +	pdev = NULL;
> +	while ((pdev =
> +		pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
> +			       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");
> +	}

Initially I wondered if this info printk could be moved into
vga_arbiter_check_bridge_sharing(), but it's been separated out since
3448a19da479b ("vgaarb: use bridges to control VGA routing where
possible."), and upon closer examination, it seems you can't be sure a
device doesn't share a bridge until the end of the process, so this is
indeed correct.

Everything else also looks good to me.

Reviewed-by: Daniel Axtens <dja@axtens.net>

Regards,
Daniel

> +
> +	vga_arb_select_default_device();
>  
>  	pr_info("loaded\n");
>  	return rc;
Daniel Vetter Oct. 17, 2017, 12:05 p.m. | #2
On Tue, Oct 17, 2017 at 01:03:46PM +1100, Daniel Axtens wrote:
> Bjorn Helgaas <bhelgaas@google.com> writes:
> 
> > The default VGA device is normally set in vga_arbiter_add_pci_device() when
> > we call it for the first enabled device that can be accessed with the
> > legacy VGA resources ([mem 0xa0000-0xbffff], etc.)
> >
> > That default device can be overridden by an EFI device that owns the boot
> > framebuffer.  As a fallback, we can also select a VGA device that can't be
> > accessed via legacy VGA resources, or a VGA device that isn't even enabled.
> >
> > Factor out this EFI and fallback selection from vga_arb_device_init() into
> > a separate vga_arb_select_default_device() function.  This doesn't change
> > any behavior, but it untangles the "bridge control possible" checking and
> > messages from the default device selection.
> >
> > Tested-by: Zhou Wang <wangzhou1@hisilicon.com>  # D05 Hisi Hip07, Hip08
> > Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> > ---
> >  drivers/gpu/vga/vgaarb.c |   57 ++++++++++++++++++++++++++++------------------
> >  1 file changed, 35 insertions(+), 22 deletions(-)
> >
> > diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
> > index 8035e38d5110..d35d6d271f3f 100644
> > --- a/drivers/gpu/vga/vgaarb.c
> > +++ b/drivers/gpu/vga/vgaarb.c
> > @@ -1402,29 +1402,14 @@ static struct miscdevice vga_arb_device = {
> >  	MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
> >  };
> >  
> > -static int __init vga_arb_device_init(void)
> > +static void __init vga_arb_select_default_device(void)
> >  {
> > -	int rc;
> >  	struct pci_dev *pdev;
> >  	struct vga_device *vgadev;
> >  
> > -	rc = misc_register(&vga_arb_device);
> > -	if (rc < 0)
> > -		pr_err("error %d registering device\n", rc);
> > -
> > -	bus_register_notifier(&pci_bus_type, &pci_notifier);
> > -
> > -	/* We add all pci devices satisfying vga class in the arbiter by
> > -	 * default */
> > -	pdev = NULL;
> > -	while ((pdev =
> > -		pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
> > -			       PCI_ANY_ID, pdev)) != NULL)
> > -		vga_arbiter_add_pci_device(pdev);
> > -
> > +#if defined(CONFIG_X86) || defined(CONFIG_IA64)
> >  	list_for_each_entry(vgadev, &vga_list, list) {
> >  		struct device *dev = &vgadev->pdev->dev;
> > -#if defined(CONFIG_X86) || defined(CONFIG_IA64)
> >  		/*
> >  		 * Override vga_arbiter_add_pci_device()'s I/O based detection
> >  		 * as it may take the wrong device (e.g. on Apple system under
> > @@ -1461,12 +1446,8 @@ static int __init vga_arb_device_init(void)
> >  				vgaarb_info(dev, "overriding boot device\n");
> >  			vga_set_default_device(vgadev->pdev);
> >  		}
> > -#endif
> > -		if (vgadev->bridge_has_one_vga)
> > -			vgaarb_info(dev, "bridge control possible\n");
> > -		else
> > -			vgaarb_info(dev, "no bridge control possible\n");
> >  	}
> > +#endif
> >  
> >  	if (!vga_default_device()) {
> >  		list_for_each_entry(vgadev, &vga_list, list) {
> > @@ -1492,6 +1473,38 @@ static int __init vga_arb_device_init(void)
> >  			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)
> > +		pr_err("error %d registering device\n", rc);
> > +
> > +	bus_register_notifier(&pci_bus_type, &pci_notifier);
> > +
> > +	/* We add all PCI devices satisfying VGA class in the arbiter by
> > +	 * default */
> > +	pdev = NULL;
> > +	while ((pdev =
> > +		pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
> > +			       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");
> > +	}
> 
> Initially I wondered if this info printk could be moved into
> vga_arbiter_check_bridge_sharing(), but it's been separated out since
> 3448a19da479b ("vgaarb: use bridges to control VGA routing where
> possible."), and upon closer examination, it seems you can't be sure a
> device doesn't share a bridge until the end of the process, so this is
> indeed correct.
> 
> Everything else also looks good to me.
> 
> Reviewed-by: Daniel Axtens <dja@axtens.net>

R-b for both patches? And ok with everyone if I pull this into drm-misc
for 4.15 (deadline is end of this week for feature-y stuff)?

Thanks, Daniel
Ard Biesheuvel Oct. 17, 2017, 12:21 p.m. | #3
On 17 October 2017 at 13:05, Daniel Vetter <daniel@ffwll.ch> wrote:
> On Tue, Oct 17, 2017 at 01:03:46PM +1100, Daniel Axtens wrote:
>> Bjorn Helgaas <bhelgaas@google.com> writes:
>>
>> > The default VGA device is normally set in vga_arbiter_add_pci_device() when
>> > we call it for the first enabled device that can be accessed with the
>> > legacy VGA resources ([mem 0xa0000-0xbffff], etc.)
>> >
>> > That default device can be overridden by an EFI device that owns the boot
>> > framebuffer.  As a fallback, we can also select a VGA device that can't be
>> > accessed via legacy VGA resources, or a VGA device that isn't even enabled.
>> >
>> > Factor out this EFI and fallback selection from vga_arb_device_init() into
>> > a separate vga_arb_select_default_device() function.  This doesn't change
>> > any behavior, but it untangles the "bridge control possible" checking and
>> > messages from the default device selection.
>> >
>> > Tested-by: Zhou Wang <wangzhou1@hisilicon.com>  # D05 Hisi Hip07, Hip08
>> > Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
>> > ---
>> >  drivers/gpu/vga/vgaarb.c |   57 ++++++++++++++++++++++++++++------------------
>> >  1 file changed, 35 insertions(+), 22 deletions(-)
>> >
>> > diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
>> > index 8035e38d5110..d35d6d271f3f 100644
>> > --- a/drivers/gpu/vga/vgaarb.c
>> > +++ b/drivers/gpu/vga/vgaarb.c
>> > @@ -1402,29 +1402,14 @@ static struct miscdevice vga_arb_device = {
>> >     MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
>> >  };
>> >
>> > -static int __init vga_arb_device_init(void)
>> > +static void __init vga_arb_select_default_device(void)
>> >  {
>> > -   int rc;
>> >     struct pci_dev *pdev;
>> >     struct vga_device *vgadev;
>> >
>> > -   rc = misc_register(&vga_arb_device);
>> > -   if (rc < 0)
>> > -           pr_err("error %d registering device\n", rc);
>> > -
>> > -   bus_register_notifier(&pci_bus_type, &pci_notifier);
>> > -
>> > -   /* We add all pci devices satisfying vga class in the arbiter by
>> > -    * default */
>> > -   pdev = NULL;
>> > -   while ((pdev =
>> > -           pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
>> > -                          PCI_ANY_ID, pdev)) != NULL)
>> > -           vga_arbiter_add_pci_device(pdev);
>> > -
>> > +#if defined(CONFIG_X86) || defined(CONFIG_IA64)
>> >     list_for_each_entry(vgadev, &vga_list, list) {
>> >             struct device *dev = &vgadev->pdev->dev;
>> > -#if defined(CONFIG_X86) || defined(CONFIG_IA64)
>> >             /*
>> >              * Override vga_arbiter_add_pci_device()'s I/O based detection
>> >              * as it may take the wrong device (e.g. on Apple system under
>> > @@ -1461,12 +1446,8 @@ static int __init vga_arb_device_init(void)
>> >                             vgaarb_info(dev, "overriding boot device\n");
>> >                     vga_set_default_device(vgadev->pdev);
>> >             }
>> > -#endif
>> > -           if (vgadev->bridge_has_one_vga)
>> > -                   vgaarb_info(dev, "bridge control possible\n");
>> > -           else
>> > -                   vgaarb_info(dev, "no bridge control possible\n");
>> >     }
>> > +#endif
>> >
>> >     if (!vga_default_device()) {
>> >             list_for_each_entry(vgadev, &vga_list, list) {
>> > @@ -1492,6 +1473,38 @@ static int __init vga_arb_device_init(void)
>> >                     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)
>> > +           pr_err("error %d registering device\n", rc);
>> > +
>> > +   bus_register_notifier(&pci_bus_type, &pci_notifier);
>> > +
>> > +   /* We add all PCI devices satisfying VGA class in the arbiter by
>> > +    * default */
>> > +   pdev = NULL;
>> > +   while ((pdev =
>> > +           pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
>> > +                          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");
>> > +   }
>>
>> Initially I wondered if this info printk could be moved into
>> vga_arbiter_check_bridge_sharing(), but it's been separated out since
>> 3448a19da479b ("vgaarb: use bridges to control VGA routing where
>> possible."), and upon closer examination, it seems you can't be sure a
>> device doesn't share a bridge until the end of the process, so this is
>> indeed correct.
>>
>> Everything else also looks good to me.
>>
>> Reviewed-by: Daniel Axtens <dja@axtens.net>
>
> R-b for both patches? And ok with everyone if I pull this into drm-misc
> for 4.15 (deadline is end of this week for feature-y stuff)?
>

For both patches

Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Daniel Axtens Oct. 18, 2017, 12:24 a.m. | #4
Hi Daniel,

>> Initially I wondered if this info printk could be moved into
>> vga_arbiter_check_bridge_sharing(), but it's been separated out since
>> 3448a19da479b ("vgaarb: use bridges to control VGA routing where
>> possible."), and upon closer examination, it seems you can't be sure a
>> device doesn't share a bridge until the end of the process, so this is
>> indeed correct.
>> 
>> Everything else also looks good to me.
>> 
>> Reviewed-by: Daniel Axtens <dja@axtens.net>
>
> R-b for both patches? And ok with everyone if I pull this into drm-misc
> for 4.15 (deadline is end of this week for feature-y stuff)?

I had only intended it for patch 2, but I've now read over patch 1 to my
satisfaction, so it too is:

Reviewed-by: Daniel Axtens <dja@axtens.net>

Thanks!

Regards,
Daniel

>
> Thanks, Daniel
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
Daniel Vetter Oct. 18, 2017, 8:18 a.m. | #5
On Wed, Oct 18, 2017 at 11:24:43AM +1100, Daniel Axtens wrote:
> Hi Daniel,
> 
> >> Initially I wondered if this info printk could be moved into
> >> vga_arbiter_check_bridge_sharing(), but it's been separated out since
> >> 3448a19da479b ("vgaarb: use bridges to control VGA routing where
> >> possible."), and upon closer examination, it seems you can't be sure a
> >> device doesn't share a bridge until the end of the process, so this is
> >> indeed correct.
> >> 
> >> Everything else also looks good to me.
> >> 
> >> Reviewed-by: Daniel Axtens <dja@axtens.net>
> >
> > R-b for both patches? And ok with everyone if I pull this into drm-misc
> > for 4.15 (deadline is end of this week for feature-y stuff)?
> 
> I had only intended it for patch 2, but I've now read over patch 1 to my
> satisfaction, so it too is:
> 
> Reviewed-by: Daniel Axtens <dja@axtens.net>

Both applied for 4.15, thanks.
-Daniel
Daniel Axtens Oct. 18, 2017, 11:05 a.m. | #6
Daniel Vetter <daniel@ffwll.ch> writes:

> On Wed, Oct 18, 2017 at 11:24:43AM +1100, Daniel Axtens wrote:
>> Hi Daniel,
>> 
>> >> Initially I wondered if this info printk could be moved into
>> >> vga_arbiter_check_bridge_sharing(), but it's been separated out since
>> >> 3448a19da479b ("vgaarb: use bridges to control VGA routing where
>> >> possible."), and upon closer examination, it seems you can't be sure a
>> >> device doesn't share a bridge until the end of the process, so this is
>> >> indeed correct.
>> >> 
>> >> Everything else also looks good to me.
>> >> 
>> >> Reviewed-by: Daniel Axtens <dja@axtens.net>
>> >
>> > R-b for both patches? And ok with everyone if I pull this into drm-misc
>> > for 4.15 (deadline is end of this week for feature-y stuff)?
>> 
>> I had only intended it for patch 2, but I've now read over patch 1 to my
>> satisfaction, so it too is:
>> 
>> Reviewed-by: Daniel Axtens <dja@axtens.net>
>
> Both applied for 4.15, thanks.

Cool - thanks!

A special thanks to Bjorn for persisting with this and coming up with a
nice simple solution :)

Regards,
Daniel

> -Daniel
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

Patch

diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
index 8035e38d5110..d35d6d271f3f 100644
--- a/drivers/gpu/vga/vgaarb.c
+++ b/drivers/gpu/vga/vgaarb.c
@@ -1402,29 +1402,14 @@  static struct miscdevice vga_arb_device = {
 	MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
 };
 
-static int __init vga_arb_device_init(void)
+static void __init vga_arb_select_default_device(void)
 {
-	int rc;
 	struct pci_dev *pdev;
 	struct vga_device *vgadev;
 
-	rc = misc_register(&vga_arb_device);
-	if (rc < 0)
-		pr_err("error %d registering device\n", rc);
-
-	bus_register_notifier(&pci_bus_type, &pci_notifier);
-
-	/* We add all pci devices satisfying vga class in the arbiter by
-	 * default */
-	pdev = NULL;
-	while ((pdev =
-		pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
-			       PCI_ANY_ID, pdev)) != NULL)
-		vga_arbiter_add_pci_device(pdev);
-
+#if defined(CONFIG_X86) || defined(CONFIG_IA64)
 	list_for_each_entry(vgadev, &vga_list, list) {
 		struct device *dev = &vgadev->pdev->dev;
-#if defined(CONFIG_X86) || defined(CONFIG_IA64)
 		/*
 		 * Override vga_arbiter_add_pci_device()'s I/O based detection
 		 * as it may take the wrong device (e.g. on Apple system under
@@ -1461,12 +1446,8 @@  static int __init vga_arb_device_init(void)
 				vgaarb_info(dev, "overriding boot device\n");
 			vga_set_default_device(vgadev->pdev);
 		}
-#endif
-		if (vgadev->bridge_has_one_vga)
-			vgaarb_info(dev, "bridge control possible\n");
-		else
-			vgaarb_info(dev, "no bridge control possible\n");
 	}
+#endif
 
 	if (!vga_default_device()) {
 		list_for_each_entry(vgadev, &vga_list, list) {
@@ -1492,6 +1473,38 @@  static int __init vga_arb_device_init(void)
 			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)
+		pr_err("error %d registering device\n", rc);
+
+	bus_register_notifier(&pci_bus_type, &pci_notifier);
+
+	/* We add all PCI devices satisfying VGA class in the arbiter by
+	 * default */
+	pdev = NULL;
+	while ((pdev =
+		pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
+			       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;