drm/radeon/kms: properly set accel working flag and bailout when false

If accel is not working many subsystem such as the ib pool might not be
initialized properly that can lead to segfault inside kernel when cs
ioctl is call with non working acceleration. To avoid this make sure
the accel working flag is false when an error in GPU startup happen and
return EBUSY from cs ioctl if accel is not working.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r100.c
index 18cd84f..333cde9 100644
--- a/drivers/gpu/drm/radeon/r100.c
+++ b/drivers/gpu/drm/radeon/r100.c
@@ -3928,6 +3928,8 @@
 
 int r100_resume(struct radeon_device *rdev)
 {
+	int r;
+
 	/* Make sur GART are not working */
 	if (rdev->flags & RADEON_IS_PCI)
 		r100_pci_gart_disable(rdev);
@@ -3947,7 +3949,11 @@
 	radeon_surface_init(rdev);
 
 	rdev->accel_working = true;
-	return r100_startup(rdev);
+	r = r100_startup(rdev);
+	if (r) {
+		rdev->accel_working = false;
+	}
+	return r;
 }
 
 int r100_suspend(struct radeon_device *rdev)