drm/ssd130x: Fix atomic_check for disabled planes

The plane's atomic_check returns -EINVAL if the CRTC has not been
set. This is the case for disabled planes, for which atomic_check
should return 0. For disabled planes, it also omits the mandatory
call to drm_atomic_helper_check_plane_state().

Replace the test with the boiler-plate code that first invokes
drm_atomic_helper_check_plane_state() and then tests for the plane
to be visible. Return early for non-visible planes.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: d51f9fbd ("drm/ssd130x: Store the HW buffer in the driver-private CRTC state")
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Tested-by: Javier Martinez Canillas <javierm@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231009141018.11291-7-tzimmermann@suse.de

drivers/gpu/drm/solomon/ssd130x.c

@@ -638,21 +638,22 @@ static int ssd130x_primary_plane_atomic_check(struct drm_plane *plane,
 	struct drm_plane_state *plane_state = drm_atomic_get_new_plane_state(state, plane);
 	struct ssd130x_plane_state *ssd130x_state = to_ssd130x_plane_state(plane_state);
 	struct drm_crtc *crtc = plane_state->crtc;
-	struct drm_crtc_state *crtc_state;
+	struct drm_crtc_state *crtc_state = NULL;
 	const struct drm_format_info *fi;
 	unsigned int pitch;
 	int ret;
 
-	if (!crtc)
-		return -EINVAL;
-
-	crtc_state = drm_atomic_get_crtc_state(state, crtc);
-	if (IS_ERR(crtc_state))
-		return PTR_ERR(crtc_state);
+	if (crtc)
+		crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
 
-	ret = drm_plane_helper_atomic_check(plane, state);
+	ret = drm_atomic_helper_check_plane_state(plane_state, crtc_state,
+						  DRM_PLANE_NO_SCALING,
+						  DRM_PLANE_NO_SCALING,
+						  false, false);
 	if (ret)
 		return ret;
+	else if (!plane_state->visible)
+		return 0;
 
 	fi = drm_format_info(DRM_FORMAT_R1);
 	if (!fi)