Hello Maxime Ripard,

The patch 65f7fa3a3fcb: "drm/sun4i: backend: Check for the number of alpha planes" from Jun 26, 2017, leads to the following static checker warning:

drivers/gpu/drm/sun4i/sun4i_backend.c:486 sun4i_backend_atomic_check() error: 'plane_state' dereferencing possible ERR_PTR()

drivers/gpu/drm/sun4i/sun4i_backend.c 462 static int sun4i_backend_atomic_check(struct sunxi_engine *engine, 463 struct drm_crtc_state *crtc_state) 464 { 465 struct drm_plane_state *plane_states[SUN4I_BACKEND_NUM_LAYERS] = { 0 }; 466 struct drm_atomic_state *state = crtc_state->state; 467 struct drm_device *drm = state->dev; 468 struct drm_plane *plane; 469 unsigned int num_planes = 0; 470 unsigned int num_alpha_planes = 0; 471 unsigned int num_frontend_planes = 0; 472 unsigned int num_yuv_planes = 0; 473 unsigned int current_pipe = 0; 474 unsigned int i; 475 476 DRM_DEBUG_DRIVER("Starting checking our planes\n"); 477 478 if (!crtc_state->planes_changed) 479 return 0; 480 481 drm_for_each_plane_mask(plane, drm, crtc_state->plane_mask) { 482 struct drm_plane_state *plane_state = 483 drm_atomic_get_plane_state(state, plane); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Not checked for failure.

484 struct sun4i_layer_state *layer_state = 485 state_to_sun4i_layer_state(plane_state); 486 struct drm_framebuffer *fb = plane_state->fb; 487 struct drm_format_name_buf format_name; 488 489 if (sun4i_backend_plane_uses_frontend(plane_state)) { 490 DRM_DEBUG_DRIVER("Using the frontend for plane %d\n", 491 plane->index); 492 493 layer_state->uses_frontend = true; 494 num_frontend_planes++; 495 } else { 496 layer_state->uses_frontend = false; 497 }

regards, dan carpenter