lib/drmtest: igt_skip when drm_get_card fails

Also add printf support to igt_skip to make sure there's always a
reason why we fail a testcase.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

tests/gem_ctx_create.c

@@ -51,9 +51,8 @@ int main(int argc, char *argv[])
 
 	ret = drmIoctl(fd, CONTEXT_CREATE_IOCTL, &create);
 	if (ret != 0 && (errno == ENODEV || errno == EINVAL)) {
-		printf("Kernel is too old, or contexts not supported: %s\n",
-			strerror(errno));
-		igt_skip();
+		igt_skip("Kernel is too old, or contexts not supported: %s\n",
+			 strerror(errno));
 	} else if (ret != 0) {
 		fprintf(stderr, "%s\n", strerror(errno));
 		igt_fail(1);

tests/gem_seqno_wrap.c

@@ -644,7 +644,6 @@ int main(int argc, char **argv)
 	parse_options(argc, argv);
 
 	card_index = drm_get_card();
-	igt_assert(card_index != -1);
 
 	srandom(time(NULL));
 

tests/kms_flip.c

@@ -628,8 +628,6 @@ static void hang_gpu(struct test_output *o)
 	int fd;
 	ssize_t r;
 
-	igt_assert(card_index != -1);
-
 	snprintf(fname, FILENAME_MAX, "%s/%i/%s",
 		 dfs_base, card_index, dfs_entry);