vgaarb: Don't default exclusively to first video device with mem+io

Commit 20cde694027e ("x86, ia64: Move EFI_FB vga_default_device()
initialization to pci_vga_fixup()") moved boot video device detection from
efifb to x86 and ia64 pci/fixup.c.

For dual-GPU Apple computers above change represents a regression as code
in efifb did forcefully override vga_default_device while the merge did not
(vgaarb happens prior to PCI fixup).

To improve on initial device selection by vgaarb (it cannot know if PCI
device not behind bridges see/decode legacy VGA I/O or not), move the
screen_info based check from pci_video_fixup() to vgaarb's init function and
use it to refine/override decision taken while adding the individual PCI
VGA devices.  This way PCI fixup has no reason to adjust vga_default_device
anymore but can depend on its value for flagging shadowed VBIOS.

This has the nice benefit of removing duplicated code but does introduce a
#if defined() block in vgaarb.  Not all architectures have screen_info and
would cause compile to fail without it.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=84461
Reported-and-Tested-By: Andreas Noever <andreas.noever@gmail.com>
Signed-off-by: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Matthew Garrett <matthew.garrett@nebula.com>
CC: stable@vger.kernel.org # v3.5+

3 files changed, 39 insertions, 47 deletions

diff --git a/arch/ia64/pci/fixup.c b/arch/ia64/pci/fixup.c
index ec73b2cf912a..fc505d58f078 100644
--- a/arch/ia64/pci/fixup.c
+++ b/arch/ia64/pci/fixup.c
@@ -38,27 +38,6 @@ static void pci_fixup_video(struct pci_dev *pdev)
                 return;
         /* Maybe, this machine supports legacy memory map. */
 
-        if (!vga_default_device()) {
-                resource_size_t start, end;
-                int i;
-
-                /* Does firmware framebuffer belong to us? */
-                for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
-                        if (!(pci_resource_flags(pdev, i) & IORESOURCE_MEM))
-                                continue;
-
-                        start = pci_resource_start(pdev, i);
-                        end  = pci_resource_end(pdev, i);
-
-                        if (!start || !end)
-                                continue;
-
-                        if (screen_info.lfb_base >= start &&
-                            (screen_info.lfb_base + screen_info.lfb_size) < end)
-                                vga_set_default_device(pdev);
-                }
-        }
-
         /* Is VGA routed to us? */
         bus = pdev->bus;
         while (bus) {
@@ -83,8 +62,7 @@ static void pci_fixup_video(struct pci_dev *pdev)
                 pci_read_config_word(pdev, PCI_COMMAND, &config);
                 if (config & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
                         pdev->resource[PCI_ROM_RESOURCE].flags |= IORESOURCE_ROM_SHADOW;
-                        dev_printk(KERN_DEBUG, &pdev->dev, "Boot video device\n");
-                        vga_set_default_device(pdev);
+                        dev_printk(KERN_DEBUG, &pdev->dev, "Video device with shadowed ROM\n");
                 }
         }
 }
diff --git a/arch/x86/pci/fixup.c b/arch/x86/pci/fixup.c
index c61ea57d1ba1..9a2b7101ae8a 100644
--- a/arch/x86/pci/fixup.c
+++ b/arch/x86/pci/fixup.c
@@ -326,27 +326,6 @@ static void pci_fixup_video(struct pci_dev *pdev)
         struct pci_bus *bus;
         u16 config;
 
-        if (!vga_default_device()) {
-                resource_size_t start, end;
-                int i;
-
-                /* Does firmware framebuffer belong to us? */
-                for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
-                        if (!(pci_resource_flags(pdev, i) & IORESOURCE_MEM))
-                                continue;
-
-                        start = pci_resource_start(pdev, i);
-                        end  = pci_resource_end(pdev, i);
-
-                        if (!start || !end)
-                                continue;
-
-                        if (screen_info.lfb_base >= start &&
-                            (screen_info.lfb_base + screen_info.lfb_size) < end)
-                                vga_set_default_device(pdev);
-                }
-        }
-
         /* Is VGA routed to us? */
         bus = pdev->bus;
         while (bus) {
@@ -371,8 +350,7 @@ static void pci_fixup_video(struct pci_dev *pdev)
                 pci_read_config_word(pdev, PCI_COMMAND, &config);
                 if (config & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
                         pdev->resource[PCI_ROM_RESOURCE].flags |= IORESOURCE_ROM_SHADOW;
-                        dev_printk(KERN_DEBUG, &pdev->dev, "Boot video device\n");
-                        vga_set_default_device(pdev);
+                        dev_printk(KERN_DEBUG, &pdev->dev, "Video device with shadowed ROM\n");
                 }
         }
 }
diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
index d2077f040f3e..24ac52e6cd41 100644
--- a/drivers/gpu/vga/vgaarb.c
+++ b/drivers/gpu/vga/vgaarb.c
@@ -41,6 +41,7 @@
 #include <linux/poll.h>
 #include <linux/miscdevice.h>
 #include <linux/slab.h>
+#include <linux/screen_info.h>
 
 #include <linux/uaccess.h>
 
@@ -585,8 +586,11 @@ static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
          */
 #ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
         if (vga_default == NULL &&
-            ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK))
+            ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)) {
+                pr_info("vgaarb: setting as boot device: PCI:%s\n",
+                        pci_name(pdev));
                 vga_set_default_device(pdev);
+        }
 #endif
 
         vga_arbiter_check_bridge_sharing(vgadev);
@@ -1320,6 +1324,38 @@ static int __init vga_arb_device_init(void)
         pr_info("vgaarb: loaded\n");
 
         list_for_each_entry(vgadev, &vga_list, list) {
+#if defined(CONFIG_X86) || defined(CONFIG_IA64)
+                /* Override I/O based detection done by vga_arbiter_add_pci_device()
+                 * 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.
+                 */
+                resource_size_t start, end;
+                int i;
+
+                /* Does firmware framebuffer belong to us? */
+                for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
+                        if (!(pci_resource_flags(vgadev->pdev, i) & IORESOURCE_MEM))
+                                continue;
+
+                        start = pci_resource_start(vgadev->pdev, i);
+                        end  = pci_resource_end(vgadev->pdev, i);
+
+                        if (!start || !end)
+                                continue;
+
+                        if (screen_info.lfb_base < start ||
+                            (screen_info.lfb_base + screen_info.lfb_size) >= end)
+                                continue;
+                        if (!vga_default_device())
+                                pr_info("vgaarb: setting as boot device: PCI:%s\n",
+                                        pci_name(vgadev->pdev));
+                        else if (vgadev->pdev != vga_default_device())
+                                pr_info("vgaarb: overriding boot device: PCI:%s\n",
+                                        pci_name(vgadev->pdev));
+                        vga_set_default_device(vgadev->pdev);
+                }
+#endif
                 if (vgadev->bridge_has_one_vga)
                         pr_info("vgaarb: bridge control possible %s\n", pci_name(vgadev->pdev));
                 else