[PATCH 1/2] drm/rockchip: vop2: fix null pointer in plane_atomic_disable

[Michael Tretter]

If the vop2_plane_atomic_disable function is called with NULL as a
state, accessing the old_pstate runs into a null pointer exception.
However, the drm_atomic_helper_disable_planes_on_crtc function calls the
atomic_disable callback with state NULL.

Allow to disable a plane without passing a plane state by checking the
old_pstate only if a state is passed.

Signed-off-by: Michael Tretter <m.tretter at pengutronix.de>
---
 drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
index aac20be5ac08..26f8a8489ded 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
@@ -996,13 +996,15 @@ static int vop2_plane_atomic_check(struct drm_plane *plane,
 static void vop2_plane_atomic_disable(struct drm_plane *plane,
 				      struct drm_atomic_state *state)
 {
-	struct drm_plane_state *old_pstate = drm_atomic_get_old_plane_state(state, plane);
+	struct drm_plane_state *old_pstate = NULL;
 	struct vop2_win *win = to_vop2_win(plane);
 	struct vop2 *vop2 = win->vop2;
 
 	drm_dbg(vop2->drm, "%s disable\n", win->data->name);
 
-	if (!old_pstate->crtc)
+	if (state)
+		old_pstate = drm_atomic_get_old_plane_state(state, plane);
+	if (old_pstate && !old_pstate->crtc)
 		return;
 
 	vop2_win_disable(win);
-- 
2.30.2