[PATCH i-g-t 6/7] tests/intel/kms_dp_linktrain_fallback: add test for validating fallback

[Kunal Joshi <kunal1.joshi@intel.com>]

add test to valdiate fallback for DP connector,
eDP subtest will be added later.

How does test validates fallback?
- test start by doing initial modeset on default mode
   (if connector is DP then we enable just that connector,
    if its DP-MST we enable all on the same topology)
- force link training failures and retrain until we reach
  lowest param or retrain is disabled
- expect hotplug and link-status to turn bad
- expect link params reduce after fallback

v2: add test for mst (imre)
    refresh mode list (imre)
    monitor got hotplugs (imre)
    check link parameter are reduced (imre)
v3: call check_fn (Santosh)
v4: handle buggy lg monitor (Imre)
    remove reset in between (Imre)
v5: fit modes wrt to bw in non-mst case as well
v6: remove LT_FAILURE_SAME_CAPS (Imre)
    explain LT_FAILURE_REDUCED_CAPS to be 2 (Imre)
    combine infra for mst and non-mst case (Imre)
    call igt_reset_link_params before setup (Imre)
    Avoid duplication setting prev_(link_rate/lane_count) (Imre)
    use the cached property name here instead of hard-coding it (Imre)
    move test logic to function (Imre)
    remove extra w/s (Imre)
    remove braces in one liners (Imre)
    enhance igt_info message (Pranay)
v7: rename kms_fallback -> kms_dp_linktrain_fallback (Imre)
    remove unused headers (Imre)
    fill mst outputs based on root id (Imre)
    check bounds for array (Imre)
    use same syntax across code (Imre)
    add todo for joined pipe (Imre)
    remove redundant commit (Imre)
v8: fail if the traversed output can't be saved (Imre)
    use TEST_ONLY commit (Imre)
    set link_status as good for all outputs in fit_modes_in_bw (Imre)
    prepare fb's with modes that fit bw (Imre)

Cc: Imre Deak <imre.deak@intel.com>
Signed-off-by: Kunal Joshi <kunal1.joshi@intel.com>
Suggested-by: Imre Deak <imre.deak@intel.com>
---
 tests/intel/kms_dp_linktrain_fallback.c | 409 ++++++++++++++++++++++++
 tests/meson.build                       |   1 +
 2 files changed, 410 insertions(+)
 create mode 100644 tests/intel/kms_dp_linktrain_fallback.c

diff --git a/tests/intel/kms_dp_linktrain_fallback.c b/tests/intel/kms_dp_linktrain_fallback.c
new file mode 100644
index 000000000..924da6d7c
--- /dev/null
+++ b/tests/intel/kms_dp_linktrain_fallback.c
@@ -0,0 +1,409 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2024 Intel Corporation
+ */
+
+/**
+ * TEST: kms dp linktrain fallback
+ * Category: Display
+ * Description: Test link training fallback for eDP/DP connectors
+ * Driver requirement: i915, xe
+ * Functionality: link training
+ * Mega feature: General Display Features
+ * Test category: functionality test
+ */
+
+#include <sys/types.h>
+
+#include "igt.h"
+
+/**
+ * SUBTEST: dp-fallback
+ * Description: Test fallback on DP connectors
+ */
+
+#define RETRAIN_COUNT 1
+/*
+ * Two consecutives link training failures
+ * reduces link params (link rate, lane count)
+ */
+#define LT_FAILURE_REDUCED_CAPS 2
+#define SPURIOUS_HPD_RETRY 3
+
+static int traversed_mst_outputs[IGT_MAX_PIPES];
+static int traversed_mst_output_count;
+typedef struct {
+	int drm_fd;
+	igt_display_t display;
+	drmModeModeInfo *mode;
+	igt_output_t *output;
+	enum pipe pipe;
+	struct igt_fb fb;
+	struct igt_plane *primary;
+	int n_pipes;
+} data_t;
+
+typedef int (*condition_check_fn)(int drm_fd, igt_output_t *output);
+
+IGT_TEST_DESCRIPTION("Test link training fallback");
+
+static void find_mst_outputs(int drm_fd, data_t *data,
+			     igt_output_t *output,
+			     igt_output_t *mst_outputs[],
+			     int *num_mst_outputs)
+{
+	int output_root_id, root_id;
+	igt_output_t *connector_output;
+
+	output_root_id = igt_get_dp_mst_connector_id(output);
+	/*
+	 * If output is MST check all other connected output which shares
+	 * same path and fill mst_outputs and num_mst_outputs
+	 */
+	for_each_connected_output(&data->display, connector_output) {
+		if (!igt_check_output_is_dp_mst(connector_output))
+			continue;
+		root_id = igt_get_dp_mst_connector_id(connector_output);
+		if (((*num_mst_outputs) < IGT_MAX_PIPES) && root_id == output_root_id)
+			mst_outputs[(*num_mst_outputs)++] = connector_output;
+	}
+}
+
+static bool setup_mst_outputs(data_t *data, igt_output_t *mst_output[],
+			      int *output_count)
+{
+	int i;
+	igt_output_t *output;
+
+	/*
+	 * Check if this is already traversed
+	 */
+	for (i = 0; i < traversed_mst_output_count; i++)
+		if (i < IGT_MAX_PIPES &&
+		    traversed_mst_outputs[i] == data->output->config.connector->connector_id)
+			return false;
+
+	find_mst_outputs(data->drm_fd, data, data->output,
+			 mst_output, output_count);
+
+	for (i = 0; i < *output_count; i++) {
+		output = mst_output[i];
+		if (traversed_mst_output_count < IGT_MAX_PIPES) {
+			traversed_mst_outputs[traversed_mst_output_count++] = output->config.connector->connector_id;
+			igt_info("Output %s is in same topology as %s\n",
+				 igt_output_name(output),
+				 igt_output_name(data->output));
+		} else {
+			igt_assert_f(false, "Unable to save traversed output\n");
+			return false;
+		}
+	}
+	return true;
+}
+
+static void setup_pipe_on_outputs(data_t *data,
+				      igt_output_t *outputs[],
+				      int *output_count)
+{
+	int i = 0;
+
+	igt_require_f(data->n_pipes >= *output_count,
+		      "Need %d pipes to assign to %d outputs\n",
+		      data->n_pipes, *output_count);
+
+	for_each_pipe(&data->display, data->pipe) {
+		if (i >= *output_count)
+			break;
+		/*
+		 * TODO: add support for modes requiring joined pipes
+		 */
+		igt_info("Setting pipe %s on output %s\n",
+			 kmstest_pipe_name(data->pipe),
+			 igt_output_name(outputs[i]));
+		igt_output_set_pipe(outputs[i++], data->pipe);
+	}
+}
+
+static void setup_modeset_on_outputs(data_t *data,
+				     igt_output_t *outputs[],
+				     int *output_count,
+				     drmModeModeInfo *mode[],
+				     struct igt_fb fb[],
+				     struct igt_plane *primary[])
+{
+	int i;
+
+	for (i = 0; i < *output_count; i++) {
+		mode[i] = igt_output_get_mode(outputs[i]);
+		igt_info("Mode %dx%d@%d on output %s\n",
+			 mode[i]->hdisplay, mode[i]->vdisplay,
+			 mode[i]->vrefresh,
+			 igt_output_name(outputs[i]));
+		primary[i] = igt_output_get_plane_type(outputs[i],
+						       DRM_PLANE_TYPE_PRIMARY);
+		igt_create_color_fb(data->drm_fd,
+				    mode[i]->hdisplay,
+				    mode[i]->vdisplay,
+				    DRM_FORMAT_XRGB8888,
+				    DRM_FORMAT_MOD_LINEAR, 0.0, 1.0, 0.0,
+				    &fb[i]);
+		igt_plane_set_fb(primary[i], &fb[i]);
+	}
+}
+
+static bool fit_modes_in_bw(data_t *data)
+{
+	bool found;
+	int ret;
+	igt_output_t *output;
+
+	/*
+	 * update the link status to good for all outputs
+	 */
+	for_each_connected_output(&data->display, output)
+		igt_output_set_prop_value(output,
+					  IGT_CONNECTOR_LINK_STATUS,
+					  DRM_MODE_LINK_STATUS_GOOD);
+
+	ret = igt_display_try_commit_atomic(&data->display,
+					    DRM_MODE_ATOMIC_TEST_ONLY |
+					    DRM_MODE_ATOMIC_ALLOW_MODESET, NULL);
+	if (ret != 0) {
+		found = igt_override_all_active_output_modes_to_fit_bw(&data->display);
+		igt_require_f(found,
+			      "No valid mode combo found for modeset\n");
+		ret = igt_display_try_commit_atomic(&data->display,
+						    DRM_MODE_ATOMIC_TEST_ONLY |
+						    DRM_MODE_ATOMIC_ALLOW_MODESET, NULL);
+		igt_require_f(ret == 0,
+			      "Commit failure during MST modeset\n");
+	}
+	return true;
+}
+
+static bool validate_modeset_for_outputs(data_t *data,
+					igt_output_t *outputs[],
+					int *output_count,
+					drmModeModeInfo *mode[],
+					struct igt_fb fb[],
+					struct igt_plane *primary[])
+{
+	igt_require_f(*output_count > 0, "Require at least 1 output\n");
+	setup_pipe_on_outputs(data, outputs, output_count);
+	igt_assert_f(fit_modes_in_bw(data), "Unable to fit modes in bw\n");
+	setup_modeset_on_outputs(data, outputs,
+				 output_count,
+				 mode, fb, primary);
+	return true;
+}
+
+static bool setup_outputs(data_t *data, bool is_mst,
+		      igt_output_t *outputs[],
+		      int *output_count, drmModeModeInfo *mode[],
+		      struct igt_fb fb[], struct igt_plane *primary[])
+{
+	bool ret;
+
+	*output_count = 0;
+
+	if (is_mst) {
+		ret = setup_mst_outputs(data, outputs, output_count);
+		if (!ret) {
+			igt_info("Skipping MST output %s as already tested\n",
+				 igt_output_name(data->output));
+			return false;
+		}
+	} else
+		if ((*output_count) < IGT_MAX_PIPES)
+			outputs[(*output_count)++] = data->output;
+
+	ret = validate_modeset_for_outputs(data, outputs,
+					   output_count, mode,
+					   fb, primary);
+
+	if (!ret) {
+		igt_info("Skipping output %s as valid pipe/output combo not found\n",
+			 igt_output_name(data->output));
+		return false;
+	}
+
+	igt_display_commit2(&data->display, COMMIT_ATOMIC);
+	return true;
+}
+
+static int check_condition_with_timeout(int drm_fd, igt_output_t *output,
+					condition_check_fn check_fn,
+					double interval, double timeout)
+{
+	struct timespec start_time, current_time;
+	double elapsed_time;
+
+	clock_gettime(CLOCK_MONOTONIC, &start_time);
+
+	while (1) {
+		if (check_fn(drm_fd, output) == 0)
+			return 0;
+
+		clock_gettime(CLOCK_MONOTONIC, &current_time);
+		elapsed_time = (current_time.tv_sec - start_time.tv_sec) +
+			(current_time.tv_nsec - start_time.tv_nsec) / 1e9;
+
+		if (elapsed_time >= timeout)
+			return -1;
+
+		usleep((useconds_t)(interval * 1000000));
+	}
+}
+
+static void test_fallback(data_t *data, bool is_mst)
+{
+	int output_count, retries;
+	int max_link_rate, curr_link_rate, prev_link_rate;
+	int max_lane_count, curr_lane_count, prev_lane_count;
+	igt_output_t *outputs[IGT_MAX_PIPES];
+	uint32_t link_status_prop_id;
+	uint64_t link_status_value;
+	drmModeModeInfo *modes[IGT_MAX_PIPES];
+	drmModePropertyPtr link_status_prop;
+	struct igt_fb fbs[IGT_MAX_PIPES];
+	struct igt_plane *primarys[IGT_MAX_PIPES];
+	struct udev_monitor *mon;
+
+	retries = SPURIOUS_HPD_RETRY;
+
+	igt_display_reset(&data->display);
+	igt_reset_link_params(data->drm_fd, data->output);
+	if (!setup_outputs(data, is_mst, outputs,
+			   &output_count, modes, fbs,
+			   primarys))
+		return;
+
+	igt_info("Testing link training fallback on %s\n",
+		 igt_output_name(data->output));
+	max_link_rate = igt_get_max_link_rate(data->drm_fd, data->output);
+	max_lane_count = igt_get_max_lane_count(data->drm_fd, data->output);
+	prev_link_rate = igt_get_current_link_rate(data->drm_fd, data->output);
+	prev_lane_count = igt_get_current_lane_count(data->drm_fd, data->output);
+
+	while (!igt_get_dp_link_retrain_disabled(data->drm_fd,
+						 data->output)) {
+		igt_info("Current link rate: %d, Current lane count: %d\n",
+			 prev_link_rate,
+			 prev_lane_count);
+		mon = igt_watch_uevents();
+		igt_force_lt_failure(data->drm_fd, data->output,
+				     LT_FAILURE_REDUCED_CAPS);
+		igt_force_link_retrain(data->drm_fd, data->output,
+				       RETRAIN_COUNT);
+
+		igt_assert_eq(check_condition_with_timeout(data->drm_fd,
+							   data->output,
+							   igt_get_dp_pending_retrain,
+							   1.0, 20.0), 0);
+		igt_assert_eq(check_condition_with_timeout(data->drm_fd,
+							   data->output,
+							   igt_get_dp_pending_lt_failures,
+							   1.0, 20.0), 0);
+
+		if (igt_get_dp_link_retrain_disabled(data->drm_fd,
+						     data->output)) {
+			igt_reset_connectors();
+			return;
+		}
+
+		igt_assert_f(igt_hotplug_detected(mon, 20),
+			     "Didn't get hotplug for force link training failure\n");
+
+		kmstest_get_property(data->drm_fd,
+				data->output->config.connector->connector_id,
+				DRM_MODE_OBJECT_CONNECTOR, "link-status",
+				&link_status_prop_id, &link_status_value,
+				&link_status_prop);
+		igt_assert_eq(link_status_value, DRM_MODE_LINK_STATUS_BAD);
+		igt_flush_uevents(mon);
+		igt_assert_f(validate_modeset_for_outputs(data,
+							  outputs,
+							  &output_count,
+							  modes,
+							  fbs,
+							  primarys),
+			     "modeset failed\n");
+		igt_display_commit2(&data->display, COMMIT_ATOMIC);
+
+		igt_assert_eq(data->output->values[IGT_CONNECTOR_LINK_STATUS], DRM_MODE_LINK_STATUS_GOOD);
+		curr_link_rate = igt_get_current_link_rate(data->drm_fd, data->output);
+		curr_lane_count = igt_get_current_lane_count(data->drm_fd, data->output);
+
+		igt_assert_f((curr_link_rate < prev_link_rate ||
+			     curr_lane_count < prev_lane_count) ||
+			     ((curr_link_rate == max_link_rate && curr_lane_count == max_lane_count) && --retries),
+			     "Fallback unsuccessful\n");
+
+		prev_link_rate = curr_link_rate;
+		prev_lane_count = curr_lane_count;
+	}
+}
+
+static bool run_test(data_t *data)
+{
+	bool ran = false;
+	igt_output_t *output;
+
+	for_each_connected_output(&data->display, output) {
+		data->output = output;
+
+		if (!igt_has_force_link_training_failure_debugfs(data->drm_fd,
+								 data->output)) {
+			igt_info("Output %s doesn't support forcing link training failure\n",
+				 igt_output_name(data->output));
+			continue;
+		}
+
+		if (output->config.connector->connector_type != DRM_MODE_CONNECTOR_DisplayPort) {
+			igt_info("Skipping output %s as it's not DP\n", output->name);
+				continue;
+		}
+
+		ran = true;
+
+		/*
+		 * Check output is MST
+		 */
+		if (igt_check_output_is_dp_mst(data->output)) {
+			igt_info("Testing MST output %s\n",
+				 igt_output_name(data->output));
+			test_fallback(data, true);
+		} else {
+			igt_info("Testing DP output %s\n",
+				 igt_output_name(data->output));
+			test_fallback(data, false);
+		}
+	}
+	return ran;
+}
+
+igt_main
+{
+	data_t data = {};
+
+	igt_fixture {
+		data.drm_fd = drm_open_driver_master(DRIVER_INTEL |
+						     DRIVER_XE);
+		kmstest_set_vt_graphics_mode();
+		igt_display_require(&data.display, data.drm_fd);
+		igt_display_require_output(&data.display);
+		for_each_pipe(&data.display, data.pipe)
+			data.n_pipes++;
+	}
+
+	igt_subtest("dp-fallback") {
+		igt_require_f(run_test(&data),
+			      "Skipping test as no output found or none supports fallback\n");
+	}
+
+	igt_fixture {
+		igt_remove_fb(data.drm_fd, &data.fb);
+		igt_display_fini(&data.display);
+		close(data.drm_fd);
+	}
+}
diff --git a/tests/meson.build b/tests/meson.build
index 00556c9d6..4adaf34f2 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -247,6 +247,7 @@ intel_kms_progs = [
 	'kms_ccs',
 	'kms_cdclk',
 	'kms_dirtyfb',
+        'kms_dp_linktrain_fallback',
 	'kms_draw_crc',
 	'kms_dsc',
 	'kms_fb_coherency',
-- 
2.43.0