PCI: Turn pci_fixup_video into generic for embedded VGA

pci_fixup_video turns into generic code because there are many platforms need this fixup
for embedded VGA as well as x86. The Video BIOS integrates into System BIOS on a machine
has embedded VGA although embedded VGA generally don't have PCI ROM. As a result,
embedded VGA need the way that the sysfs rom points to the Video BIOS of System
RAM (0xC0000). PCI-to-PCI Bridge Architecture specification describes the condition whether
or not PCI ROM forwards VGA compatible memory address. fixup_video suits this specification.
Although the Video ROM generally implements in x86 code regardless of platform, some
application such as X Window System can run this code by dosemu86. Therefore,
pci_fixup_video should turn into generic code.


Signed-off-by: Eiichiro Oiwa <eiichiro.oiwa.nm@hitachi.com>
Acked-by: Alan Cox <alan@redhat.com>
Acked-by: Jesse Barnes <jesse.barnes@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/pci/rom.c b/drivers/pci/rom.c
index f5ee7ce16fa6..43e4a49f2cc4 100644
--- a/drivers/pci/rom.c
+++ b/drivers/pci/rom.c
@@ -71,7 +71,10 @@ void __iomem *pci_map_rom(struct pci_dev *pdev, size_t *size)
         void __iomem *image;
         int last_image;
 
-        /* IORESOURCE_ROM_SHADOW only set on x86 */
+        /*
+         * IORESOURCE_ROM_SHADOW set if the VGA enable bit of the Bridge Control
+         * register is set for embedded VGA.
+         */
         if (res->flags & IORESOURCE_ROM_SHADOW) {
                 /* primary video rom always starts here */
                 start = (loff_t)0xC0000;