drm/rockchip: vop: Disable planes when disabling CRTC

When a VOP is re-enabled, it will start scanning right away the
framebuffers that were configured from the last time, even if those have
been destroyed already.

To prevent the VOP from trying to access freed memory, disable all its
windows when the CRTC is being disabled, then each window will get a
valid framebuffer address before it's enabled again.
Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Link: http://lkml.kernel.org/g/CAAObsKAv+05ih5U+=4kic_NsjGMhfxYheHR8xXXmacZs+p5SHw@mail.gmail.com

drivers/gpu/drm/rockchip/rockchip_drm_vop.c

@@ -499,10 +499,25 @@ static void vop_enable(struct drm_crtc *crtc)
 static void vop_crtc_disable(struct drm_crtc *crtc)
 {
 	struct vop *vop = to_vop(crtc);
+	int i;
 
 	if (!vop->is_enabled)
 		return;
 
+	/*
+	 * We need to make sure that all windows are disabled before we
+	 * disable that crtc. Otherwise we might try to scan from a destroyed
+	 * buffer later.
+	 */
+	for (i = 0; i < vop->data->win_size; i++) {
+		struct vop_win *vop_win = &vop->win[i];
+		const struct vop_win_data *win = vop_win->data;
+
+		spin_lock(&vop->reg_lock);
+		VOP_WIN_SET(vop, win, enable, 0);
+		spin_unlock(&vop->reg_lock);
+	}
+
 	drm_crtc_vblank_off(crtc);
 
 	/*