[PATCH] vesafb: Disable mtrr as the default

vesafb occassionally gets the size wrong when setting the mtrr.  When X or DRI
attempts to set the mtrr, it will fail due to range overlap significantly
affecting their performance.  Disable mtrr and let the user explicitly enable
it with the mtrr:n option.
Signed-off-by: NAntonino Daplas <adaplas@pol.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Documentation/fb/vesafb.txt

@@ -146,10 +146,10 @@ pmipal	Use the protected mode interface for palette changes.
 
 mtrr:n	setup memory type range registers for the vesafb framebuffer
 	where n:
-	      0 - disabled (equivalent to nomtrr)
+	      0 - disabled (equivalent to nomtrr) (default)
 	      1 - uncachable
 	      2 - write-back
-	      3 - write-combining (default)
+	      3 - write-combining
 	      4 - write-through
 
 	If you see the following in dmesg, choose the type that matches the

drivers/video/vesafb.c

@@ -48,7 +48,7 @@ static struct fb_fix_screeninfo vesafb_fix __initdata = {
 };
 
 static int             inverse   = 0;
-static int             mtrr      = 3; /* default to write-combining */
+static int             mtrr      = 0; /* disable mtrr */
 static int	       vram_remap __initdata = 0; /* Set amount of memory to be used */
 static int	       vram_total __initdata = 0; /* Set total amount of memory */
 static int             pmi_setpal = 0;	/* pmi for palette changes ??? */