compositor-drm: Remove no_addfb2 handling

If AddFB2 ever fails for any reason, we fall back to legacy AddFB, which
doesn't support the same swathe of formats, or multi-planar formats, or
modifiers.

This can happen with arbitrary client buffers, condemning us to the
fallback forever more. Remove this, at the cost of an unnecessary ioctl
for users on old kernels without AddFB2; unfortunately, we cannot detect
the complete absence of the ioctl, as the return here is -EINVAL rather
than -ENOTTY.

A check for whether or not the format is valid has been replaced with an
assert, as its callers either check that the format is non-zero, return
a FourCC format code from GBM, or use a static FourCC format.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>

libweston/compositor-drm.c

@@ -241,7 +241,6 @@ struct drm_backend {
 	 */
 	int min_width, max_width;
 	int min_height, max_height;
-	int no_addfb2;
 
 	struct wl_list plane_list;
 	int sprites_are_broken;
@@ -854,6 +853,7 @@ drm_fb_create_dumb(struct drm_backend *b, int width, int height,
 	struct drm_mode_create_dumb create_arg;
 	struct drm_mode_destroy_dumb destroy_arg;
 	struct drm_mode_map_dumb map_arg;
+	uint32_t handles[4] = { 0 }, pitches[4] = { 0 }, offsets[4] = { 0 };
 
 	fb = zalloc(sizeof *fb);
 	if (!fb)
@@ -893,23 +893,12 @@ drm_fb_create_dumb(struct drm_backend *b, int width, int height,
 
 	ret = -1;
 
-	if (!b->no_addfb2) {
-		uint32_t handles[4] = { 0 }, pitches[4] = { 0 }, offsets[4] = { 0 };
-
-		handles[0] = fb->handle;
-		pitches[0] = fb->stride;
-		offsets[0] = 0;
-
-		ret = drmModeAddFB2(b->drm.fd, width, height,
-				    fb->format->format,
-				    handles, pitches, offsets,
-				    &fb->fb_id, 0);
-		if (ret) {
-			weston_log("addfb2 failed: %m\n");
-			b->no_addfb2 = 1;
-		}
-	}
+	handles[0] = fb->handle;
+	pitches[0] = fb->stride;
+	offsets[0] = 0;
 
+	ret = drmModeAddFB2(b->drm.fd, width, height, fb->format->format,
+			    handles, pitches, offsets, &fb->fb_id, 0);
 	if (ret) {
 		ret = drmModeAddFB(b->drm.fd, width, height,
 				   fb->format->depth, fb->format->bpp,
@@ -963,6 +952,8 @@ drm_fb_get_from_bo(struct gbm_bo *bo, struct drm_backend *backend,
 		return drm_fb_ref(fb);
 	}
 
+	assert(format != 0);
+
 	fb = zalloc(sizeof *fb);
 	if (fb == NULL)
 		return NULL;
@@ -993,23 +984,13 @@ drm_fb_get_from_bo(struct gbm_bo *bo, struct drm_backend *backend,
 		goto err_free;
 	}
 
-	ret = -1;
-
-	if (format && !backend->no_addfb2) {
-		handles[0] = fb->handle;
-		pitches[0] = fb->stride;
-		offsets[0] = 0;
-
-		ret = drmModeAddFB2(backend->drm.fd, fb->width, fb->height,
-				    format, handles, pitches, offsets,
-				    &fb->fb_id, 0);
-		if (ret) {
-			weston_log("addfb2 failed: %m\n");
-			backend->no_addfb2 = 1;
-			backend->sprites_are_broken = 1;
-		}
-	}
+	handles[0] = fb->handle;
+	pitches[0] = fb->stride;
+	offsets[0] = 0;
 
+	ret = drmModeAddFB2(backend->drm.fd, fb->width, fb->height,
+			    fb->format->format, handles, pitches, offsets,
+			    &fb->fb_id, 0);
 	if (ret && fb->format->depth && fb->format->bpp)
 		ret = drmModeAddFB(backend->drm.fd, fb->width, fb->height,
 				   fb->format->depth, fb->format->bpp,