1 files changed, 22 insertions, 18 deletions

diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
index af0259708358..d2077f040f3e 100644
--- a/drivers/gpu/vga/vgaarb.c
+++ b/drivers/gpu/vga/vgaarb.c
@@ -237,12 +237,10 @@ static struct vga_device *__vga_tryget(struct vga_device *vgadev,
                 if (conflict->locks & lwants)
                         return conflict;
 
-                /* Ok, now check if he owns the resource we want. We don't need
-                 * to check "decodes" since it should be impossible to own
-                 * own legacy resources you don't decode unless I have a bug
-                 * in this code...
+                /* Ok, now check if it owns the resource we want.  We can
+                 * lock resources that are not decoded, therefore a device
+                 * can own resources it doesn't decode.
                  */
-                WARN_ON(conflict->owns & ~conflict->decodes);
                 match = lwants & conflict->owns;
                 if (!match)
                         continue;
@@ -254,13 +252,19 @@ static struct vga_device *__vga_tryget(struct vga_device *vgadev,
                 flags = 0;
                 pci_bits = 0;
 
+                /* If we can't control legacy resources via the bridge, we
+                 * also need to disable normal decoding.
+                 */
                 if (!conflict->bridge_has_one_vga) {
-                        vga_irq_set_state(conflict, false);
-                        flags |= PCI_VGA_STATE_CHANGE_DECODES;
-                        if (match & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
+                        if ((match & conflict->decodes) & VGA_RSRC_LEGACY_MEM)
                                 pci_bits |= PCI_COMMAND_MEMORY;
-                        if (match & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
+                        if ((match & conflict->decodes) & VGA_RSRC_LEGACY_IO)
                                 pci_bits |= PCI_COMMAND_IO;
+
+                        if (pci_bits) {
+                                vga_irq_set_state(conflict, false);
+                                flags |= PCI_VGA_STATE_CHANGE_DECODES;
+                        }
                 }
 
                 if (change_bridge)
@@ -268,18 +272,19 @@ static struct vga_device *__vga_tryget(struct vga_device *vgadev,
 
                 pci_set_vga_state(conflict->pdev, false, pci_bits, flags);
                 conflict->owns &= ~match;
-                /* If he also owned non-legacy, that is no longer the case */
-                if (match & VGA_RSRC_LEGACY_MEM)
+
+                /* If we disabled normal decoding, reflect it in owns */
+                if (pci_bits & PCI_COMMAND_MEMORY)
                         conflict->owns &= ~VGA_RSRC_NORMAL_MEM;
-                if (match & VGA_RSRC_LEGACY_IO)
+                if (pci_bits & PCI_COMMAND_IO)
                         conflict->owns &= ~VGA_RSRC_NORMAL_IO;
         }
 
 enable_them:
         /* ok dude, we got it, everybody conflicting has been disabled, let's
-         * enable us. Make sure we don't mark a bit in "owns" that we don't
-         * also have in "decodes". We can lock resources we don't decode but
-         * not own them.
+         * enable us.  Mark any bits in "owns" regardless of whether we
+         * decoded them.  We can lock resources we don't decode, therefore
+         * we must track them via "owns".
          */
         flags = 0;
         pci_bits = 0;
@@ -291,7 +296,7 @@ enable_them:
                 if (wants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
                         pci_bits |= PCI_COMMAND_IO;
         }
-        if (!!(wants & VGA_RSRC_LEGACY_MASK))
+        if (wants & VGA_RSRC_LEGACY_MASK)
                 flags |= PCI_VGA_STATE_CHANGE_BRIDGE;
 
         pci_set_vga_state(vgadev->pdev, true, pci_bits, flags);
@@ -299,7 +304,7 @@ enable_them:
         if (!vgadev->bridge_has_one_vga) {
                 vga_irq_set_state(vgadev, true);
         }
-        vgadev->owns |= (wants & vgadev->decodes);
+        vgadev->owns |= wants;
 lock_them:
         vgadev->locks |= (rsrc & VGA_RSRC_LEGACY_MASK);
         if (rsrc & VGA_RSRC_LEGACY_IO)
@@ -649,7 +654,6 @@ static inline void vga_update_device_decodes(struct vga_device *vgadev,
         old_decodes = vgadev->decodes;
         decodes_removed = ~new_decodes & old_decodes;
         decodes_unlocked = vgadev->locks & decodes_removed;
-        vgadev->owns &= ~decodes_removed;
         vgadev->decodes = new_decodes;
 
         pr_info("vgaarb: device changed decodes: PCI:%s,olddecodes=%s,decodes=%s:owns=%s\n",