drm/tinydrm: Advertise that we can do only DRM_FORMAT_MOD_LINEAR.

Without this, the xserver relies on what the 3D driver exposes and
assumes that the display can handle it, and then the DRM driver
happily tries to scan out a tiled format.

Signed-off-by: Eric Anholt <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]
Acked-by: Noralf Trønnes <[e-mail]>

drivers/gpu/drm/drm_simple_kms_helper.c

···
 	pipe->funcs->cleanup_fb(pipe, state);
 }
 
+static bool drm_simple_kms_format_mod_supported(struct drm_plane *plane,
+						uint32_t format,
+						uint64_t modifier)
+{
+	return modifier == DRM_FORMAT_MOD_LINEAR;
+}
+
 static const struct drm_plane_helper_funcs drm_simple_kms_plane_helper_funcs = {
 	.prepare_fb = drm_simple_kms_plane_prepare_fb,
 	.cleanup_fb = drm_simple_kms_plane_cleanup_fb,
···
 	.reset			= drm_atomic_helper_plane_reset,
 	.atomic_duplicate_state	= drm_atomic_helper_plane_duplicate_state,
 	.atomic_destroy_state	= drm_atomic_helper_plane_destroy_state,
+	.format_mod_supported   = drm_simple_kms_format_mod_supported,
 };
 
 /**

drivers/gpu/drm/tinydrm/core/tinydrm-core.c

···
 	drm->dev_private = tdev;
 	drm_mode_config_init(drm);
 	drm->mode_config.funcs = &tinydrm_mode_config_funcs;
+	drm->mode_config.allow_fb_modifiers = true;
 
 	return 0;
 }

drivers/gpu/drm/tinydrm/core/tinydrm-pipe.c

···
 	struct drm_display_mode mode_copy;
 	struct drm_connector *connector;
 	int ret;
+	static const uint64_t modifiers[] = {
+		DRM_FORMAT_MOD_LINEAR,
+		DRM_FORMAT_MOD_INVALID
+	};
 
 	drm_mode_copy(&mode_copy, mode);
 	ret = tinydrm_rotate_mode(&mode_copy, rotation);
···
 		return PTR_ERR(connector);
 
 	return drm_simple_display_pipe_init(drm, &tdev->pipe, funcs, formats,
-					    format_count, NULL, connector);
+					    format_count, modifiers, connector);
 }
 EXPORT_SYMBOL(tinydrm_display_pipe_init);