backlight: Allow enable/disable of fb backlights, fixing regressions

Enabling the backlight by default appears to cause problems for many
users. This patch disables backlight controls unless explicitly
enabled by users via a module parameter. Since PMAC users are known
to work, default to enabled in that case.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
diff --git a/drivers/video/aty/radeon_base.c b/drivers/video/aty/radeon_base.c
index 46ba123..1bf6f42 100644
--- a/drivers/video/aty/radeon_base.c
+++ b/drivers/video/aty/radeon_base.c
@@ -268,6 +268,11 @@
 #endif
 static int force_sleep;
 static int ignore_devlist;
+#ifdef CONFIG_PMAC_BACKLIGHT
+static int backlight = 1;
+#else
+static int backlight = 0;
+#endif
 
 /*
  * prototypes
@@ -2348,7 +2353,8 @@
 						 MTRR_TYPE_WRCOMB, 1);
 #endif
 
-	radeonfb_bl_init(rinfo);
+	if (backlight)
+		radeonfb_bl_init(rinfo);
 
 	printk ("radeonfb (%s): %s\n", pci_name(rinfo->pdev), rinfo->name);
 
@@ -2469,6 +2475,8 @@
 			force_dfp = 1;
 		} else if (!strncmp(this_opt, "panel_yres:", 11)) {
 			panel_yres = simple_strtoul((this_opt+11), NULL, 0);
+		} else if (!strncmp(this_opt, "backlight:", 10)) {
+			backlight = simple_strtoul(this_opt+10, NULL, 0);
 #ifdef CONFIG_MTRR
 		} else if (!strncmp(this_opt, "nomtrr", 6)) {
 			nomtrr = 1;