drm/vc4: Fix YUV plane handling when planes are in different buffers

YUV images can either be presented as one allocation with offsets
for the different planes, or multiple allocations with 0 offsets.

The driver only ever calls drm_fb_[dma|cma]_get_gem_obj with plane
index 0, therefore any application using the second approach was
incorrectly rendered.

Correctly determine the address for each plane, removing the
assumption that the base address is the same for each.

Fixes: fc04023 ("drm/vc4: Add support for YUV planes.")
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20230127155708.454704-1-maxime@cerno.tech

drivers/gpu/drm/vc4/vc4_plane.c

@@ -340,7 +340,7 @@ static int vc4_plane_setup_clipping_and_scaling(struct drm_plane_state *state)
 {
 	struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);
 	struct drm_framebuffer *fb = state->fb;
-	struct drm_gem_dma_object *bo = drm_fb_dma_get_gem_obj(fb, 0);
+	struct drm_gem_dma_object *bo;
 	int num_planes = fb->format->num_planes;
 	struct drm_crtc_state *crtc_state;
 	u32 h_subsample = fb->format->hsub;
@@ -359,8 +359,10 @@ static int vc4_plane_setup_clipping_and_scaling(struct drm_plane_state *state)
 	if (ret)
 		return ret;
 
-	for (i = 0; i < num_planes; i++)
+	for (i = 0; i < num_planes; i++) {
+		bo = drm_fb_dma_get_gem_obj(fb, i);
 		vc4_state->offsets[i] = bo->dma_addr + fb->offsets[i];
+	}
 
 	/*
 	 * We don't support subpixel source positioning for scaling,