radeonfb: Disable new color expand acceleration unless explicitely enabled

This new color expansion acceleration for radeonfb appears to trigger
problems with X on VT switch and suspend/resume on some machines. It
might be a problem in the VT layer or in X, but I haven't quite found
it yet, so in the meantime, this disables the acceleration by default,
reverting to 2.6.27 state. It can be enabled using the "accel_cexp"
module parameter or fbdev argument.

Signed-off-by: Benjamin Herrenschmidt <[e-mail]>
Acked-by: David S. Miller <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/video/aty/radeon_accel.c

···
 		return;
 
 	/* We only do 1 bpp color expansion for now */
-	if (info->flags & FBINFO_HWACCEL_DISABLED || image->depth != 1)
+	if (!accel_cexp ||
+	    (info->flags & FBINFO_HWACCEL_DISABLED) || image->depth != 1)
 		goto fallback;
 
 	/* Fallback if running out of the screen. We may do clipping

drivers/video/aty/radeon_base.c

···
 static int backlight = 0;
 #endif
 
+int accel_cexp = 0;
+
 /*
  * prototypes
  */
···
 		} else if (!strncmp(this_opt, "ignore_devlist", 14)) {
 			ignore_devlist = 1;
 #endif
+		} else if (!strncmp(this_opt, "accel_cexp", 12)) {
+			accel_cexp = 1;
 		} else
 			mode_option = this_opt;
 	}
···
 MODULE_PARM_DESC(monitor_layout, "Specify monitor mapping (like XFree86)");
 module_param(force_measure_pll, bool, 0);
 MODULE_PARM_DESC(force_measure_pll, "Force measurement of PLL (debug)");
+module_param(accel_cexp, bool, 0);
+MODULE_PARM_DESC(accel_cexp, "Use acceleration engine for color expansion");
 #ifdef CONFIG_MTRR
 module_param(nomtrr, bool, 0);
 MODULE_PARM_DESC(nomtrr, "bool: disable use of MTRR registers");

drivers/video/aty/radeonfb.h

···
 static inline void radeonfb_bl_exit(struct radeonfb_info *rinfo) {}
 #endif
 
+extern int accel_cexp;
+
 #endif /* __RADEONFB_H__ */