--- radeon_backlight.c.orig	2007-03-21 22:53:31.000000000 +0100
+++ radeon_backlight.c	2007-03-25 21:36:19.000000000 +0200
@@ -58,7 +58,7 @@
 	u32 lvds_gen_cntl, tmpPixclksCntl;
 	int level;
 
-	if (rinfo->mon1_type != MT_LCD)
+	if (PRIMARY_MONITOR(rinfo) != MT_LCD)
 		return 0;
 
 	/* We turn off the LCD completely instead of just dimming the
@@ -146,7 +146,7 @@
 	struct radeon_bl_privdata *pdata;
 	char name[12];
 
-	if (rinfo->mon1_type != MT_LCD)
+	if (PRIMARY_MONITOR(rinfo) == MT_LCD) {
 		return;
 
 #ifdef CONFIG_PMAC_BACKLIGHT