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/rs400.c b/drivers/gpu/drm/radeon/rs400.c
index b0ce84a..866a05b 100644
--- a/drivers/gpu/drm/radeon/rs400.c
+++ b/drivers/gpu/drm/radeon/rs400.c
@@ -442,6 +442,8 @@
 
 int rs400_resume(struct radeon_device *rdev)
 {
+	int r;
+
 	/* Make sur GART are not working */
 	rs400_gart_disable(rdev);
 	/* Resume clock before doing reset */
@@ -462,7 +464,11 @@
 	radeon_surface_init(rdev);
 
 	rdev->accel_working = true;
-	return rs400_startup(rdev);
+	r = rs400_startup(rdev);
+	if (r) {
+		rdev->accel_working = false;
+	}
+	return r;
 }
 
 int rs400_suspend(struct radeon_device *rdev)