[PATCH v2 2/2] drm/connector: hdmi: Implement "min bpc" property

[Nicolas Frattaroli <nicolas.frattaroli@collabora.com>]

Act on the "min bpc" property's min_requested_bpc state in the common
HDMI state helpers, and register the property on HDMI connectors.

Also add two KUnit tests to verify that the property behaves as
expected.

Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
 drivers/gpu/drm/display/drm_hdmi_state_helper.c    |  10 +-
 drivers/gpu/drm/drm_connector.c                    |   4 +
 drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c | 146 +++++++++++++++++++++
 3 files changed, 156 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
index ce17eeefc2da..fa015d218b41 100644
--- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
+++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
@@ -636,10 +636,12 @@ hdmi_compute_format_bpc(const struct drm_connector *connector,
 			unsigned int max_bpc, enum drm_output_color_format fmt)
 {
 	struct drm_device *dev = connector->dev;
-	unsigned int bpc;
+	unsigned int bpc, min_bpc;
 	int ret;
 
-	for (bpc = max_bpc; bpc >= 8; bpc -= 2) {
+	min_bpc = max(conn_state->min_requested_bpc, 8);
+
+	for (bpc = max_bpc; bpc >= min_bpc; bpc -= 2) {
 		ret = hdmi_try_format_bpc(connector, conn_state, mode, bpc, fmt);
 		if (!ret)
 			continue;
@@ -657,8 +659,8 @@ hdmi_compute_format_bpc(const struct drm_connector *connector,
 		return 0;
 	}
 
-	drm_dbg_kms(dev, "Failed. %s output format not supported for any bpc count.\n",
-		    drm_hdmi_connector_get_output_format_name(fmt));
+	drm_dbg_kms(dev, "Failed. %s output format not supported for any bpc <= %u and >= %u.\n",
+		    drm_hdmi_connector_get_output_format_name(fmt), max_bpc, min_bpc);
 
 	return -EINVAL;
 }
diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 3ecc079404a1..f019bd5fef69 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -640,6 +640,10 @@ int drmm_connector_hdmi_init(struct drm_device *dev,
 	if (ret)
 		return ret;
 
+	ret = drm_connector_attach_min_bpc_property(connector, max_bpc);
+	if (ret)
+		return ret;
+
 	connector->hdmi.funcs = hdmi_funcs;
 
 	return 0;
diff --git a/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c b/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
index 353a261d42da..8f8f7a528e08 100644
--- a/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
+++ b/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
@@ -1361,6 +1361,150 @@ static void drm_test_check_tmds_char_rate_rgb_12bpc(struct kunit *test)
 	drm_modeset_acquire_fini(&ctx);
 }
 
+/*
+ * Test that an atomic check with a min bpc of 10 fails on a connector that
+ * maxes out at 8bpc even if the EDID could go higher.
+ */
+static void drm_test_check_min_bpc_10bit_connector_fail(struct kunit *test)
+{
+	struct drm_atomic_helper_connector_hdmi_priv *priv;
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_connector_state *conn_state;
+	struct drm_display_mode *preferred;
+	struct drm_atomic_commit *state;
+	struct drm_connector *conn;
+	struct drm_device *drm;
+	int ret;
+
+	priv = drm_kunit_helper_connector_hdmi_init_with_edid_funcs(test,
+				BIT(DRM_OUTPUT_COLOR_FORMAT_RGB444) |
+				BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR420) |
+				BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR422) |
+				BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR444),
+				8,
+				&dummy_connector_hdmi_funcs,
+				test_edid_hdmi_1080p_rgb_yuv_dc_max_340mhz);
+	KUNIT_ASSERT_NOT_NULL(test, priv);
+
+	drm = &priv->drm;
+	conn = &priv->connector;
+	preferred = find_preferred_mode(conn);
+	KUNIT_ASSERT_NOT_NULL(test, preferred);
+
+	drm_modeset_acquire_init(&ctx, 0);
+
+retry_conn_enable:
+	ret = drm_kunit_helper_enable_crtc_connector(test, drm, priv->crtc,
+						     conn, preferred, &ctx);
+	if (ret == -EDEADLK) {
+		ret = drm_modeset_backoff(&ctx);
+		if (!ret)
+			goto retry_conn_enable;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	state = drm_kunit_helper_atomic_state_alloc(test, drm, &ctx);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, state);
+
+retry_conn_state:
+	conn_state = drm_atomic_get_connector_state(state, conn);
+	if (PTR_ERR(conn_state) == -EDEADLK) {
+		drm_atomic_commit_clear(state);
+		ret = drm_modeset_backoff(&ctx);
+		if (!ret)
+			goto retry_conn_state;
+	}
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, conn_state);
+
+	conn_state->min_requested_bpc = 10;
+
+	ret = drm_atomic_check_only(state);
+	if (ret == -EDEADLK) {
+		drm_atomic_commit_clear(state);
+		ret = drm_modeset_backoff(&ctx);
+		if (!ret)
+			goto retry_conn_state;
+	}
+	KUNIT_EXPECT_LT(test, ret, 0);
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+}
+
+/*
+ * Test that an atomic check with a min bpc of 10 succeeds on a connector that
+ * can do 10bpc if the EDID can also do 10bpc.
+ */
+static void drm_test_check_min_bpc_10bit_success(struct kunit *test)
+{
+	struct drm_atomic_helper_connector_hdmi_priv *priv;
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_connector_state *conn_state;
+	struct drm_display_mode *preferred;
+	struct drm_atomic_commit *state;
+	struct drm_connector *conn;
+	struct drm_device *drm;
+	int ret;
+
+	priv = drm_kunit_helper_connector_hdmi_init_with_edid_funcs(test,
+				BIT(DRM_OUTPUT_COLOR_FORMAT_RGB444),
+				12,
+				&dummy_connector_hdmi_funcs,
+				test_edid_hdmi_1080p_rgb_yuv_dc_max_340mhz);
+	KUNIT_ASSERT_NOT_NULL(test, priv);
+
+	drm = &priv->drm;
+	conn = &priv->connector;
+	preferred = find_preferred_mode(conn);
+	KUNIT_ASSERT_NOT_NULL(test, preferred);
+	KUNIT_ASSERT_TRUE(test, conn->display_info.edid_hdmi_rgb444_dc_modes &
+				DRM_EDID_HDMI_DC_30);
+
+	drm_modeset_acquire_init(&ctx, 0);
+
+retry_conn_enable:
+	ret = drm_kunit_helper_enable_crtc_connector(test, drm, priv->crtc,
+						     conn, preferred, &ctx);
+	if (ret == -EDEADLK) {
+		ret = drm_modeset_backoff(&ctx);
+		if (!ret)
+			goto retry_conn_enable;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	state = drm_kunit_helper_atomic_state_alloc(test, drm, &ctx);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, state);
+
+retry_conn_state:
+	conn_state = drm_atomic_get_connector_state(state, conn);
+	if (PTR_ERR(conn_state) == -EDEADLK) {
+		drm_atomic_commit_clear(state);
+		ret = drm_modeset_backoff(&ctx);
+		if (!ret)
+			goto retry_conn_state;
+	}
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, conn_state);
+
+	conn_state->min_requested_bpc = 10;
+
+	ret = drm_atomic_check_only(state);
+	if (ret == -EDEADLK) {
+		drm_atomic_commit_clear(state);
+		ret = drm_modeset_backoff(&ctx);
+		if (!ret)
+			goto retry_conn_state;
+	}
+	KUNIT_EXPECT_EQ(test, ret, 0);
+
+	conn_state = drm_atomic_get_new_connector_state(state, conn);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, conn_state);
+	KUNIT_EXPECT_GE(test, conn_state->hdmi.output_bpc, 10);
+	KUNIT_ASSERT_EQ(test, conn_state->hdmi.output_format, DRM_OUTPUT_COLOR_FORMAT_RGB444);
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+}
+
 /*
  * Test that if we filter a rate through our hook, it's indeed rejected
  * by the whole atomic_check logic.
@@ -2476,6 +2620,8 @@ static struct kunit_case drm_atomic_helper_connector_hdmi_check_tests[] = {
 	KUNIT_CASE(drm_test_check_tmds_char_rate_rgb_8bpc),
 	KUNIT_CASE(drm_test_check_tmds_char_rate_rgb_10bpc),
 	KUNIT_CASE(drm_test_check_tmds_char_rate_rgb_12bpc),
+	KUNIT_CASE(drm_test_check_min_bpc_10bit_connector_fail),
+	KUNIT_CASE(drm_test_check_min_bpc_10bit_success),
 	KUNIT_CASE_PARAM(drm_test_check_hdmi_color_format,
 			 check_hdmi_color_format_gen_params),
 	KUNIT_CASE_PARAM(drm_test_check_hdmi_color_format_420_only,

-- 
2.55.0