drm/radeon/kms: Use radeon_agp_disable when disabling AGP

Use same common function to disable agp so we replace the GART
callback by the proper one when we do so. This fix oops if
radeon_agp_init report failure.

This patch also move radeon_agp_init out of *_mc_init for r600
& rv770 so that we can have a similar behavior than for previous
hw, ie if agp_init fails it will fallback to GPU GART and disable
AGP.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/r600.c b/drivers/gpu/drm/radeon/r600.c
index 3e02dd4..b3713f6 100644
--- a/drivers/gpu/drm/radeon/r600.c
+++ b/drivers/gpu/drm/radeon/r600.c
@@ -624,7 +624,6 @@
 	fixed20_12 a;
 	u32 tmp;
 	int chansize, numchan;
-	int r;
 
 	/* Get VRAM informations */
 	rdev->mc.vram_is_ddr = true;
@@ -667,9 +666,6 @@
 		rdev->mc.real_vram_size = rdev->mc.aper_size;
 
 	if (rdev->flags & RADEON_IS_AGP) {
-		r = radeon_agp_init(rdev);
-		if (r)
-			return r;
 		/* gtt_size is setup by radeon_agp_init */
 		rdev->mc.gtt_location = rdev->mc.agp_base;
 		tmp = 0xFFFFFFFFUL - rdev->mc.agp_base - rdev->mc.gtt_size;
@@ -2028,6 +2024,11 @@
 	r = radeon_fence_driver_init(rdev);
 	if (r)
 		return r;
+	if (rdev->flags & RADEON_IS_AGP) {
+		r = radeon_agp_init(rdev);
+		if (r)
+			radeon_agp_disable(rdev);
+	}
 	r = r600_mc_init(rdev);
 	if (r)
 		return r;