None of the drm_bridge function have kunit tests so far. Let's change
that, starting with drm_bridge_get_current_state().

Reviewed-by: Dmitry Baryshkov <dmitry.barysh...@linaro.org>
Signed-off-by: Maxime Ripard <mrip...@kernel.org>
---
 drivers/gpu/drm/Kconfig                 |   1 +
 drivers/gpu/drm/tests/Makefile          |   1 +
 drivers/gpu/drm/tests/drm_bridge_test.c | 210 ++++++++++++++++++++++++++++++++
 3 files changed, 212 insertions(+)

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 
e5b59de28216385f3783373e636d193d38d02646..9b406123132912f0578e9c8288d4c80e65f75f67
 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -72,10 +72,11 @@ config DRM_KUNIT_TEST_HELPERS
          KUnit Helpers for KMS drivers.
 
 config DRM_KUNIT_TEST
        tristate "KUnit tests for DRM" if !KUNIT_ALL_TESTS
        depends on DRM && KUNIT && MMU
+       select DRM_BRIDGE_CONNECTOR
        select DRM_BUDDY
        select DRM_DISPLAY_DP_HELPER
        select DRM_DISPLAY_HDMI_STATE_HELPER
        select DRM_DISPLAY_HELPER
        select DRM_EXEC
diff --git a/drivers/gpu/drm/tests/Makefile b/drivers/gpu/drm/tests/Makefile
index 
0109bcf7faa54993cce337f522eae78f0fa6ffcb..6691c577d2d4581a4185bac2ce89a6b14b339b35
 100644
--- a/drivers/gpu/drm/tests/Makefile
+++ b/drivers/gpu/drm/tests/Makefile
@@ -3,10 +3,11 @@
 obj-$(CONFIG_DRM_KUNIT_TEST_HELPERS) += \
        drm_kunit_helpers.o
 
 obj-$(CONFIG_DRM_KUNIT_TEST) += \
        drm_atomic_state_test.o \
+       drm_bridge_test.o \
        drm_buddy_test.o \
        drm_cmdline_parser_test.o \
        drm_connector_test.o \
        drm_damage_helper_test.o \
        drm_dp_mst_helper_test.o \
diff --git a/drivers/gpu/drm/tests/drm_bridge_test.c 
b/drivers/gpu/drm/tests/drm_bridge_test.c
new file mode 100644
index 
0000000000000000000000000000000000000000..c0a05c459d957c3f9d281957f002f6bd36cce367
--- /dev/null
+++ b/drivers/gpu/drm/tests/drm_bridge_test.c
@@ -0,0 +1,210 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Kunit test for drm_bridge functions
+ */
+#include <drm/drm_atomic_state_helper.h>
+#include <drm/drm_bridge.h>
+#include <drm/drm_bridge_connector.h>
+#include <drm/drm_kunit_helpers.h>
+
+#include <kunit/test.h>
+
+struct drm_bridge_init_priv {
+       struct drm_device drm;
+       struct drm_plane *plane;
+       struct drm_crtc *crtc;
+       struct drm_encoder encoder;
+       struct drm_bridge bridge;
+       struct drm_connector *connector;
+};
+
+static const struct drm_bridge_funcs drm_test_bridge_legacy_funcs = {
+};
+
+static const struct drm_bridge_funcs drm_test_bridge_atomic_funcs = {
+       .atomic_destroy_state   = drm_atomic_helper_bridge_destroy_state,
+       .atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
+       .atomic_reset           = drm_atomic_helper_bridge_reset,
+};
+
+KUNIT_DEFINE_ACTION_WRAPPER(drm_bridge_remove_wrapper,
+                           drm_bridge_remove,
+                           struct drm_bridge *);
+
+static int drm_kunit_bridge_add(struct kunit *test,
+                               struct drm_bridge *bridge)
+{
+       drm_bridge_add(bridge);
+
+       return kunit_add_action_or_reset(test,
+                                        drm_bridge_remove_wrapper,
+                                        bridge);
+}
+
+static struct drm_bridge_init_priv *
+drm_test_bridge_init(struct kunit *test, const struct drm_bridge_funcs *funcs)
+{
+       struct drm_bridge_init_priv *priv;
+       struct drm_encoder *enc;
+       struct drm_bridge *bridge;
+       struct drm_device *drm;
+       struct device *dev;
+       int ret;
+
+       dev = drm_kunit_helper_alloc_device(test);
+       if (IS_ERR(dev))
+               return ERR_CAST(dev);
+
+       priv = drm_kunit_helper_alloc_drm_device(test, dev,
+                                                struct drm_bridge_init_priv, 
drm,
+                                                DRIVER_MODESET | 
DRIVER_ATOMIC);
+       if (IS_ERR(priv))
+               return ERR_CAST(priv);
+
+       drm = &priv->drm;
+       priv->plane = drm_kunit_helper_create_primary_plane(test, drm,
+                                                           NULL,
+                                                           NULL,
+                                                           NULL, 0,
+                                                           NULL);
+       if (IS_ERR(priv->plane))
+               return ERR_CAST(priv->plane);
+
+       priv->crtc = drm_kunit_helper_create_crtc(test, drm,
+                                                 priv->plane, NULL,
+                                                 NULL,
+                                                 NULL);
+       if (IS_ERR(priv->crtc))
+               return ERR_CAST(priv->crtc);
+
+       enc = &priv->encoder;
+       ret = drmm_encoder_init(drm, enc, NULL, DRM_MODE_ENCODER_TMDS, NULL);
+       if (ret)
+               return ERR_PTR(ret);
+
+       enc->possible_crtcs = drm_crtc_mask(priv->crtc);
+
+       bridge = &priv->bridge;
+       bridge->type = DRM_MODE_CONNECTOR_VIRTUAL;
+       bridge->funcs = funcs;
+
+       ret = drm_kunit_bridge_add(test, bridge);
+       if (ret)
+               return ERR_PTR(ret);
+
+       ret = drm_bridge_attach(enc, bridge, NULL, 0);
+       if (ret)
+               return ERR_PTR(ret);
+
+       priv->connector = drm_bridge_connector_init(drm, enc);
+       if (IS_ERR(priv->connector))
+               return ERR_CAST(priv->connector);
+
+       drm_connector_attach_encoder(priv->connector, enc);
+
+       drm_mode_config_reset(drm);
+
+       return priv;
+}
+
+/*
+ * Test that drm_bridge_get_current_state() returns the last committed
+ * state for an atomic bridge.
+ */
+static void drm_test_drm_bridge_get_current_state_atomic(struct kunit *test)
+{
+       struct drm_modeset_acquire_ctx ctx;
+       struct drm_bridge_init_priv *priv;
+       struct drm_bridge_state *curr_bridge_state;
+       struct drm_bridge_state *bridge_state;
+       struct drm_atomic_state *state;
+       struct drm_bridge *bridge;
+       struct drm_device *drm;
+       int ret;
+
+       priv = drm_test_bridge_init(test, &drm_test_bridge_atomic_funcs);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv);
+
+       drm_modeset_acquire_init(&ctx, 0);
+
+       drm = &priv->drm;
+       state = drm_kunit_helper_atomic_state_alloc(test, drm, &ctx);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, state);
+
+retry_commit:
+       bridge = &priv->bridge;
+       bridge_state = drm_atomic_get_bridge_state(state, bridge);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, bridge_state);
+
+       ret = drm_atomic_commit(state);
+       if (ret == -EDEADLK) {
+               drm_atomic_state_clear(state);
+               drm_modeset_backoff(&ctx);
+               goto retry_commit;
+       }
+       KUNIT_ASSERT_EQ(test, ret, 0);
+
+       drm_modeset_drop_locks(&ctx);
+       drm_modeset_acquire_fini(&ctx);
+
+       drm_modeset_acquire_init(&ctx, 0);
+
+retry_state:
+       ret = drm_modeset_lock(&bridge->base.lock, &ctx);
+       if (ret == -EDEADLK) {
+               drm_modeset_backoff(&ctx);
+               goto retry_state;
+       }
+
+       curr_bridge_state = drm_bridge_get_current_state(bridge);
+       KUNIT_EXPECT_PTR_EQ(test, curr_bridge_state, bridge_state);
+
+       drm_modeset_unlock(&bridge->base.lock);
+
+       drm_modeset_drop_locks(&ctx);
+       drm_modeset_acquire_fini(&ctx);
+}
+
+/*
+ * Test that drm_bridge_get_current_state() returns NULL for a
+ * non-atomic bridge.
+ */
+static void drm_test_drm_bridge_get_current_state_legacy(struct kunit *test)
+{
+       struct drm_bridge_init_priv *priv;
+       struct drm_bridge *bridge;
+
+       priv = drm_test_bridge_init(test, &drm_test_bridge_legacy_funcs);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv);
+
+       /*
+        * NOTE: Strictly speaking, we should take the bridge->base.lock
+        * before calling that function. However, bridge->base is only
+        * initialized if the bridge is atomic, while we explicitly
+        * initialize one that isn't there.
+        *
+        * In order to avoid unnecessary warnings, let's skip the
+        * locking. The function would return NULL in all cases anyway,
+        * so we don't really have any concurrency to worry about.
+        */
+       bridge = &priv->bridge;
+       KUNIT_EXPECT_NULL(test, drm_bridge_get_current_state(bridge));
+}
+
+static struct kunit_case drm_bridge_get_current_state_tests[] = {
+       KUNIT_CASE(drm_test_drm_bridge_get_current_state_atomic),
+       KUNIT_CASE(drm_test_drm_bridge_get_current_state_legacy),
+       { }
+};
+
+
+static struct kunit_suite drm_bridge_get_current_state_test_suite = {
+       .name = "drm_test_bridge_get_current_state",
+       .test_cases = drm_bridge_get_current_state_tests,
+};
+
+kunit_test_suite(drm_bridge_get_current_state_test_suite);
+
+MODULE_AUTHOR("Maxime Ripard <mrip...@kernel.org>");
+MODULE_DESCRIPTION("Kunit test for drm_bridge functions");
+MODULE_LICENSE("GPL");

-- 
2.48.1

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