Merge ../linus

[linux-drm-fsl-dcu.git] / drivers / char / agp / generic.c

diff --git a/drivers/char/agp/generic.c b/drivers/char/agp/generic.c
index 5ff457b41efbc4b4a349fa4ee90e4413c6249134..883a36a278332ee6912ab9f19be236e3548ec5aa 100644 (file)
--- 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) {