2 files changed, 27 insertions, 2 deletions

diff --git a/drivers/char/agp/Kconfig b/drivers/char/agp/Kconfig
index c603bf291580..a9f9c48c2424 100644
--- a/drivers/char/agp/Kconfig
+++ b/drivers/char/agp/Kconfig
@@ -86,7 +86,7 @@ config AGP_NVIDIA
 
 config AGP_SIS
         tristate "SiS chipset support"
-        depends on AGP
+        depends on AGP && X86
         help
           This option gives you AGP support for the GLX component of
           X on Silicon Integrated Systems [SiS] chipsets.
@@ -103,7 +103,7 @@ config AGP_SWORKS
 
 config AGP_VIA
         tristate "VIA chipset support"
-        depends on AGP
+        depends on AGP && X86
         help
           This option gives you AGP support for the GLX component of
           X on VIA MVP3/Apollo Pro chipsets.
diff --git a/drivers/char/agp/generic.c b/drivers/char/agp/generic.c
index 5ff457b41efb..883a36a27833 100644
--- a/drivers/char/agp/generic.c
+++ b/drivers/char/agp/generic.c
@@ -419,6 +419,31 @@ static void agp_v2_parse_one(u32 *requested_mode, u32 *bridge_agpstat, u32 *vga_
                 *requested_mode &= ~AGP2_RESERVED_MASK;
         }
 
+        /*
+         * Some dumb bridges are programmed to disobey the AGP2 spec.
+         * This is likely a BIOS misprogramming rather than poweron default, or
+         * it would be a lot more common.
+         * https://bugs.freedesktop.org/show_bug.cgi?id=8816
+         * AGPv2 spec 6.1.9 states:
+         *   The RATE field indicates the data transfer rates supported by this
+         *   device. A.G.P. devices must report all that apply.
+         * Fix them up as best we can.
+         */
+        switch (*bridge_agpstat & 7) {
+        case 4:
+                *bridge_agpstat |= (AGPSTAT2_2X | AGPSTAT2_1X);
+                printk(KERN_INFO PFX "BIOS bug. AGP bridge claims to only support x4 rate"
+                        "Fixing up support for x2 & x1\n");
+                break;
+        case 2:
+                *bridge_agpstat |= AGPSTAT2_1X;
+                printk(KERN_INFO PFX "BIOS bug. AGP bridge claims to only support x2 rate"
+                        "Fixing up support for x1\n");
+                break;
+        default:
+                break;
+        }
+
         /* Check the speed bits make sense. Only one should be set. */
         tmp = *requested_mode & 7;
         switch (tmp) {