[PATCH i-g-t 12/39] lib/vkms: Test CRTC invalid values

["José Expósito" <jose.exposito89@gmail.com>]

For a VKMS CRTC, it is only possible to set invalid values in the
writeback connector status.

Test that setting wrong values fails and that the CRTC status is not
accidentally changed.

Signed-off-by: José Expósito <jose.exposito89@gmail.com>
---
 lib/igt_vkms.c             | 20 ++++++++++++++++++++
 lib/igt_vkms.h             |  2 ++
 tests/vkms/vkms_configfs.c | 27 +++++++++++++++++++++++++++
 3 files changed, 49 insertions(+)

diff --git a/lib/igt_vkms.c b/lib/igt_vkms.c
index 4021f9aea..d881a2417 100644
--- a/lib/igt_vkms.c
+++ b/lib/igt_vkms.c
@@ -396,3 +396,23 @@ bool igt_vkms_crtc_is_writeback_enabled(igt_vkms_t *dev, const char *name)
 
 	return read_bool(path);
 }
+
+/**
+ * igt_vkms_crtc_set_writeback_enabled:
+ * @dev: Device the CRTC belongs to
+ * @name: CRTC name
+ * @writeback: Enable or disable the writeback connector
+ *
+ * Set the VKMS CRTC writeback connector is status.
+ */
+void igt_vkms_crtc_set_writeback_enabled(igt_vkms_t *dev, const char *name,
+					 bool writeback)
+{
+	char path[PATH_MAX];
+
+	snprintf(path, sizeof(path), "%s/%s/%s/%s", dev->path,
+		 get_pipeline_item_dir_name(VKMS_PIPELINE_ITEM_CRTC), name,
+		 VKMS_FILE_CRTC_WRITEBACK);
+
+	write_bool(path, writeback);
+}
diff --git a/lib/igt_vkms.h b/lib/igt_vkms.h
index 59f6a9775..cb0278544 100644
--- a/lib/igt_vkms.h
+++ b/lib/igt_vkms.h
@@ -35,5 +35,7 @@ void igt_vkms_plane_set_type(igt_vkms_t *dev, const char *name, int type);
 
 void igt_vkms_device_add_crtc(igt_vkms_t *dev, const char *name);
 bool igt_vkms_crtc_is_writeback_enabled(igt_vkms_t *dev, const char *name);
+void igt_vkms_crtc_set_writeback_enabled(igt_vkms_t *dev, const char *name,
+					 bool writeback);
 
 #endif /* __IGT_VKMS_H__ */
diff --git a/tests/vkms/vkms_configfs.c b/tests/vkms/vkms_configfs.c
index 95779d336..af42e364d 100644
--- a/tests/vkms/vkms_configfs.c
+++ b/tests/vkms/vkms_configfs.c
@@ -319,6 +319,32 @@ static void test_crtc_default_values(void)
 	igt_vkms_device_destroy(dev);
 }
 
+/**
+ * SUBTEST: crtc-wrong-values
+ * Description: Check that setting unexpected values doesn't work.
+ */
+
+static void test_crtc_wrong_values(void)
+{
+	igt_vkms_t *dev;
+	char path[PATH_MAX];
+
+	/* Test invalid values for "writeback" */
+	dev = igt_vkms_device_create(__func__);
+	igt_assert(dev);
+
+	igt_vkms_device_add_crtc(dev, "crtc0");
+	igt_vkms_crtc_set_writeback_enabled(dev, "crtc0", true);
+	igt_assert(igt_vkms_crtc_is_writeback_enabled(dev, "crtc0"));
+
+	snprintf(path, sizeof(path), "%s/crtcs/crtc0/writeback", dev->path);
+
+	assert_wrong_bool_values(path);
+	igt_assert(igt_vkms_crtc_is_writeback_enabled(dev, "crtc0"));
+
+	igt_vkms_device_destroy(dev);
+}
+
 igt_main
 {
 	struct {
@@ -333,6 +359,7 @@ igt_main
 		{ "plane-wrong-values", test_plane_wrong_values },
 		{ "crtc-default-files", test_crtc_default_files },
 		{ "crtc-default-values", test_crtc_default_values },
+		{ "crtc-wrong-values", test_crtc_wrong_values },
 	};
 
 	igt_fixture {
-- 
2.48.1