Hi Jeevan,

Adds a test to verify DC3CO continues to function properly
after a DC6 power cycle.

Signed-off-by: Jeevan B <jeevan.b@intel.com>
---
 tests/intel/kms_pm_dc.c | 65 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/tests/intel/kms_pm_dc.c b/tests/intel/kms_pm_dc.c
index 22ae51b51..6d2bd0ee1 100644
--- a/tests/intel/kms_pm_dc.c
+++ b/tests/intel/kms_pm_dc.c
@@ -55,6 +55,11 @@
  * Description: Verify that DC3CO entry does not cause frame drops and successfully
  * 		enters the power state
  *
+ * SUBTEST: dc3co-after-dc6
+ * Description: Verify DC3CO entry is still functional after a DC6 entry and
+ *              exit cycle, ensuring DC3CO is not broken by deeper power state
+ *              transitions.
+ *
  * SUBTEST: dc5-dpms
  * Description: Validate display engine entry to DC5 state while all connectors's
  *              DPMS property set to OFF
@@ -629,6 +634,42 @@ static int has_panels_without_dc_support(igt_display_t *display)
 	return external_panel;
 }
 
+static void test_dc3co_after_dc6(data_t *data, enum psr_mode mode)
+{
+	uint32_t dc6_prev_cnt;
+
+	igt_require_dc_counter(data->debugfs_fd, IGT_INTEL_CHECK_DC3CO);
+	igt_require_dc_counter(data->debugfs_fd, IGT_INTEL_CHECK_DC6);
+
+	setup_output(data);
+
+	/* Enable PSR2/PR */
+	data->op_psr_mode = mode;

+	psr_enable(data->drm_fd, data->debugfs_fd, data->op_psr_mode, NULL);
+	igt_require_f(psr_wait_entry(data->debugfs_fd, data->op_psr_mode, NULL),
+		      "%s is not enabled\n",
+		      mode == PSR_MODE_2 ? "PSR2" : "Panel Replay");
+
+	/* Trigger a DC6 cycle */
+	dc6_prev_cnt = igt_read_dc_counter(data->debugfs_fd, IGT_INTEL_CHECK_DC6);
+	setup_dc_dpms(data);
+	dpms_off(data);
+	assert_dc_counter(data, IGT_INTEL_CHECK_DC6, dc6_prev_cnt);
+	dpms_on(data);
+	cleanup_dc_dpms(data);

+
+	/* Re-enable PSR2/PR after DC6 exit */
+	psr_enable(data->drm_fd, data->debugfs_fd, data->op_psr_mode, NULL);

+	igt_require_f(psr_wait_entry(data->debugfs_fd, data->op_psr_mode, NULL),
+		      "%s not re-enabled after DC6 exit\n",
+		      mode == PSR_MODE_2 ? "PSR2" : "Panel Replay");
+
+	/* Verify DC3CO still works after DC6 */
+	setup_videoplayback(data);
+	check_dc3co_with_videoplayback_like_load(data);
+	cleanup_dc3co_fbs(data);
+}
+
 static void test_deep_pkgc_state(data_t *data)
 {
 	unsigned int pre_val = 0, cur_val = 0;
@@ -799,6 +840,30 @@ int igt_main()
 		}
 	}
 
+	igt_describe("Verify DC3CO entry is still functional after a DC6 entry "
+		     "and exit cycle");
+	igt_subtest_with_dynamic("dc3co-after-dc6") {
+		igt_dynamic("psr2") {
+			igt_require(psr_sink_support(data.drm_fd, data.debugfs_fd,
+						     PSR_MODE_2, NULL));
+			igt_require_f(IS_TIGERLAKE(data.devid) ||
+				      intel_display_ver(data.devid) >= 35,
+				      "Platform does not support DC3CO with PSR2\n");
+			igt_require_f(igt_pm_pc8_plus_residencies_enabled(data.msr_fd),
+				      "PC8+ residencies not supported\n");
+			test_dc3co_after_dc6(&data, PSR_MODE_2);
+		}
+		igt_dynamic("pr") {
+			igt_require(psr_sink_support(data.drm_fd, data.debugfs_fd,
+						     PR_MODE, NULL));
+			igt_require_f(intel_display_ver(data.devid) >= 35,
+				      "Platform does not support DC3CO with Panel Replay\n");
+			igt_require_f(igt_pm_pc8_plus_residencies_enabled(data.msr_fd),
+				      "PC8+ residencies not supported\n");
+			test_dc3co_after_dc6(&data, PR_MODE);
+		}
+	}
+
 	igt_describe("This test validates display engine entry to DC5 state "
 		     "while PSR is active");
 	igt_subtest("dc5-psr") {