From: Eryk Brol <redacted>

[Why]
Having a test that iterates through different link
settings and performs link training with them is useful
and currently missing from IGT.

[How]
Add a link settings test and its required helper functions.

Signed-off-by: Stylon Wang <redacted>
---
 lib/igt_amd.c                    | 119 +++++++++++++
 lib/igt_amd.h                    |  44 +++++
 tests/amdgpu/amd_link_settings.c | 280 +++++++++++++++++++++++++++++++
 tests/amdgpu/meson.build         |   1 +
 4 files changed, 444 insertions(+)
 create mode 100644 tests/amdgpu/amd_link_settings.c

diff --git a/lib/igt_amd.c b/lib/igt_amd.c
index 4ffe7cf2..f1bfb421 100644
--- a/lib/igt_amd.c
+++ b/lib/igt_amd.c

@@ -323,3 +323,122 @@ int igt_amd_trigger_hotplug(int drm_fd, char *connector_name)
 
 	return 0;
 }
+
+/*
+ * igt_amd_read_link_settings:
+ * @drm_fd: DRM file descriptor
+ * @connector_name: The name of the connector to read the link_settings
+ * @lane_count: Lane count
+ * @link_rate: Link rate
+ * @link_spread: Spread spectrum
+ *
+ * The indices of @lane_count, @link_rate, and @link_spread correspond to the
+ * values of "Current", "Verified", "Reported", and "Preferred", respectively.
+ */
+void igt_amd_read_link_settings(
+	int drm_fd, char *connector_name, int *lane_count, int *link_rate, int *link_spread)
+{
+	int fd, ret;
+	char buf[101];
+	int i = 0;
+	char *token_end, *val_token;
+
+	fd = igt_debugfs_connector_dir(drm_fd, connector_name, O_RDONLY);
+	if (fd < 0) {
+		igt_info("Could not open connector %s debugfs directory\n",
+			 connector_name);
+		return;
+	}
+	ret = igt_debugfs_simple_read(fd, DEBUGFS_DP_LINK_SETTINGS, buf, sizeof(buf));
+	igt_assert_f(ret >= 0, "Reading %s for connector %s failed.\n",
+		     DEBUGFS_DP_LINK_SETTINGS, connector_name);
+
+	close(fd);
+
+	/* Between current, verified, reported, and preferred are null terminators,
+	 * replace them with ';' to use as the delimiter for strtok. */
+	while (strlen(buf) < sizeof(buf) - 1 && buf[strlen(buf)] == '\0')
+		buf[strlen(buf)] = ';';
+
+	/* Parse values read from file. */
+	for (char *token = strtok_r(buf, ";", &token_end);
+	     token != NULL;
+	     token = strtok_r(NULL, ";", &token_end))
+	{
+		strtok_r(token, ": ", &val_token);
+		lane_count[i] = strtol(val_token, &val_token, 10);
+		link_rate[i] = strtol(val_token, &val_token, 10);
+		link_spread[i] = strtol(val_token, &val_token, 10);
+		i++;
+
+		if (i > 3) return;
+	}
+}
+
+/*
+ * igt_amd_write_link_settings:
+ * @drm_fd: DRM file descriptor
+ * @connector_name: The name of the connector to write the link_settings
+ * @lane_count: Lane count
+ * @link_rate: Link rate
+ * @training_type: Link training type
+ */
+void igt_amd_write_link_settings(
+	int drm_fd, char *connector_name, enum dc_lane_count lane_count,
+	enum dc_link_rate link_rate, enum dc_link_training_type training_type)
+{
+	int ls_fd, fd;
+	const int buf_len = 40;
+	char buf[buf_len];
+	int wr_len = 0;
+
+	memset(buf, '\0', sizeof(char) * buf_len);
+
+	fd = igt_debugfs_connector_dir(drm_fd, connector_name, O_RDONLY);
+	igt_assert(fd >= 0);
+	ls_fd = openat(fd, DEBUGFS_DP_LINK_SETTINGS, O_WRONLY);
+	close(fd);
+	igt_assert(ls_fd >= 0);
+
+	/* dp_link_settings_write expects a \n at the end or else it will
+	 * dereference a null pointer.
+	 */
+	if (training_type == LINK_TRAINING_DEFAULT)
+		snprintf(buf, sizeof(buf), "%02x %02x \n", lane_count, link_rate);
+	else
+		snprintf(buf, sizeof(buf), "%02x %02x %02x \n", lane_count,
+			 link_rate, training_type);
+
+	wr_len = write(ls_fd, buf, strlen(buf));
+	igt_assert_eq(wr_len, strlen(buf));
+
+	close(ls_fd);
+}
+
+/**
+ * igt_amd_output_has_link_settings: check if connector has link_settings debugfs entry
+ * @drm_fd: DRM file descriptor
+ * @connector_name: The connector's name, on which we're reading the status
+ */
+bool igt_amd_output_has_link_settings(int drm_fd, char *connector_name)
+{
+	int fd;
+	int res;
+	struct stat stat;
+
+	fd = igt_debugfs_connector_dir(drm_fd, connector_name, O_RDONLY);
+	if (fd < 0) {
+		igt_info("output %s: debugfs not found\n", connector_name);
+		return false;
+	}
+
+	res = fstatat(fd, DEBUGFS_DP_LINK_SETTINGS, &stat, 0);
+	if (res != 0) {
+		igt_info("output %s: %s debugfs not supported\n", connector_name, DEBUGFS_DP_LINK_SETTINGS);
+		close(fd);
+		return false;
+	}
+
+	close(fd);
+	return true;
+}

diff --git a/lib/igt_amd.h b/lib/igt_amd.h
index d333ad9c..e5bdbf33 100644
--- a/lib/igt_amd.h
+++ b/lib/igt_amd.h

@@ -27,8 +27,44 @@
 #include "igt.h"
 #include "igt_fb.h"
 
+#define DEBUGFS_DP_LINK_SETTINGS "link_settings"
 #define DEBUGFS_HPD_TRIGGER "trigger_hotplug"
 
+enum dc_lane_count {
+	LANE_COUNT_UNKNOWN = 0,
+	LANE_COUNT_ONE = 1,
+	LANE_COUNT_TWO = 2,
+	LANE_COUNT_FOUR = 4,
+	LANE_COUNT_EIGHT = 8,
+	LANE_COUNT_DP_MAX = LANE_COUNT_FOUR
+};
+
+/* This is actually a reference clock (27MHz) multiplier
+ * 162MBps bandwidth for 1.62GHz like rate,
+ * 270MBps for 2.70GHz,
+ * 324MBps for 3.24Ghz,
+ * 540MBps for 5.40GHz
+ * 810MBps for 8.10GHz
+ */
+enum dc_link_rate {
+	LINK_RATE_UNKNOWN = 0,
+	LINK_RATE_LOW = 0x06,		// Rate_1 (RBR)	- 1.62 Gbps/Lane
+	LINK_RATE_RATE_2 = 0x08,	// Rate_2		- 2.16 Gbps/Lane
+	LINK_RATE_RATE_3 = 0x09,	// Rate_3		- 2.43 Gbps/Lane
+	LINK_RATE_HIGH = 0x0A,		// Rate_4 (HBR)	- 2.70 Gbps/Lane
+	LINK_RATE_RBR2 = 0x0C,		// Rate_5 (RBR2)- 3.24 Gbps/Lane
+	LINK_RATE_RATE_6 = 0x10,	// Rate_6		- 4.32 Gbps/Lane
+	LINK_RATE_HIGH2 = 0x14,		// Rate_7 (HBR2)- 5.40 Gbps/Lane
+	LINK_RATE_HIGH3 = 0x1E		// Rate_8 (HBR3)- 8.10 Gbps/Lane
+};
+
+enum dc_link_training_type {
+	LINK_TRAINING_DEFAULT = 0,
+	LINK_TRAINING_SLOW = 0,
+	LINK_TRAINING_FAST,
+	LINK_TRAINING_NO_PATTERN
+};
+
 uint32_t igt_amd_create_bo(int fd, uint64_t size);
 void *igt_amd_mmap_bo(int fd, uint32_t handle, uint64_t size, int prot);
 unsigned int igt_amd_compute_offset(unsigned int* swizzle_pattern,

@@ -48,4 +84,12 @@ bool igt_amd_is_tiled(uint64_t modifier);
 void igt_amd_require_hpd(igt_display_t *display, int drm_fd);
 int igt_amd_trigger_hotplug(int drm_fd, char *connector_name);
 
+/* IGT link helper functions */
+void igt_amd_read_link_settings(
+	int drm_fd, char *connector_name, int *lane_count, int *link_rate, int *link_spread);
+void igt_amd_write_link_settings(
+	int drm_fd, char *connector_name, enum dc_lane_count lane_count,
+	enum dc_link_rate link_rate, enum dc_link_training_type training_type);
+bool igt_amd_output_has_link_settings(int drm_fd, char *connector_name);
+
 #endif /* IGT_AMD_H */

diff --git a/tests/amdgpu/amd_link_settings.c b/tests/amdgpu/amd_link_settings.c
new file mode 100644
index 00000000..7822683d
--- /dev/null
+++ b/tests/amdgpu/amd_link_settings.c

@@ -0,0 +1,280 @@
+/*
+ * Copyright 2020 Advanced Micro Devices, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include "igt.h"
+#include "igt_amd.h"
+
+typedef struct
+{
+	int drm_fd;
+        igt_display_t display;
+        igt_plane_t *primary;
+        igt_output_t *output;
+	igt_fb_t fb;
+	igt_pipe_crc_t *pipe_crc;
+	igt_pipe_t *pipe;
+        enum pipe pipe_id;
+	int connector_type;
+	int w, h;
+	igt_crc_t crc_640_480;
+} data_t;
+
+drmModeModeInfo mode_640_480 = {
+	.name		= "640x480",
+	.vrefresh	= 60,
+	.clock		= 25200,
+
+	.hdisplay	= 640,
+	.hsync_start	= 656,
+	.hsync_end	= 752,
+	.htotal		= 800,
+
+	.vdisplay	= 480,
+	.vsync_start	= 490,
+	.vsync_end	= 492,
+	.vtotal		= 525,
+
+	.flags		= DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
+};
+
+const enum dc_lane_count lane_count_values[] =
+{
+	LANE_COUNT_ONE,
+	LANE_COUNT_TWO,
+	LANE_COUNT_FOUR,
+};
+
+const enum dc_link_rate dp_link_rate_values[] =
+{
+	LINK_RATE_LOW,
+	LINK_RATE_HIGH,
+	LINK_RATE_HIGH2,
+	LINK_RATE_HIGH3
+};
+
+const enum dc_link_rate edp_link_rate_values[] =
+{
+	LINK_RATE_LOW,
+	LINK_RATE_HIGH,
+	LINK_RATE_RBR2,
+	LINK_RATE_HIGH2
+};
+
+static void test_fini(data_t *data)
+{
+	igt_pipe_crc_free(data->pipe_crc);
+	igt_display_reset(&data->display);
+}
+
+static void set_all_output_pipe_to_none(data_t *data)
+{
+	igt_output_t *output;
+
+	for_each_connected_output(&data->display, output) {
+		igt_output_set_pipe(output, PIPE_NONE);
+	}
+
+	igt_display_commit_atomic(&data->display, DRM_MODE_ATOMIC_ALLOW_MODESET, NULL);
+}
+
+static void test_init(data_t *data, igt_output_t *output)
+{
+	enum pipe pipe;
+
+	igt_require(output->config.connector->count_modes >= 1);
+
+	set_all_output_pipe_to_none(data);
+
+	for_each_pipe(&data->display, pipe) {
+		if (igt_pipe_connector_valid(pipe, output)) {
+			data->pipe_id = pipe;
+			break;
+		}
+	}
+
+	data->connector_type = output->config.connector->connector_type;
+
+	igt_require(data->pipe_id != PIPE_NONE);
+
+	data->pipe = &data->display.pipes[data->pipe_id];
+	data->pipe_crc = igt_pipe_crc_new(data->drm_fd, data->pipe_id, "auto");
+
+	igt_output_set_pipe(output, data->pipe_id);
+
+	data->primary = igt_output_get_plane_type(output, DRM_PLANE_TYPE_PRIMARY);
+}
+
+static void run_link_training_config(data_t *data, igt_output_t *output)
+{
+	int lane_count[4], link_rate[4], link_spread[4];
+	int max_lc, max_lr;
+	const int current = 0;
+	const int verified = 1;
+	char *connector_name = output->name;
+	igt_crc_t crc;
+	const enum dc_link_rate *link_rate_values;
+	int num_link_rates;
+	if (data->connector_type == DRM_MODE_CONNECTOR_DisplayPort) {
+		link_rate_values = dp_link_rate_values;
+		num_link_rates = ARRAY_SIZE(dp_link_rate_values);
+	} else if (data->connector_type == DRM_MODE_CONNECTOR_eDP) {
+		link_rate_values = edp_link_rate_values;
+		num_link_rates = ARRAY_SIZE(edp_link_rate_values);
+	} else {
+		igt_info("Not a DP or eDP connector\n");
+		return;
+	}
+
+	igt_amd_read_link_settings(data->drm_fd, connector_name, lane_count,
+			           link_rate, link_spread);
+
+	max_lc = lane_count[verified];
+	max_lr = link_rate[verified];
+
+	for (int i = 0; i < ARRAY_SIZE(lane_count_values); i++)
+	{
+		if (lane_count_values[i] > max_lc)
+			continue;
+
+		for (int j = 0; j < num_link_rates; j++)
+		{
+			if (link_rate_values[j] > max_lr)
+				continue;
+
+			/* Write link settings */
+			igt_info("Applying lane count: %d, link rate 0x%02x, on default training\n",
+				  lane_count_values[i], link_rate_values[j]);
+			igt_amd_write_link_settings(data->drm_fd, connector_name,
+						    lane_count_values[i],
+						    link_rate_values[j],
+						    LINK_TRAINING_DEFAULT);
+
+			/* Commit */
+			igt_create_pattern_fb(data->drm_fd, mode_640_480.hdisplay,
+					      mode_640_480.vdisplay, DRM_FORMAT_XRGB8888,
+					      0, &data->fb);
+			igt_plane_set_fb(data->primary, &data->fb);
+			igt_display_commit_atomic(&data->display, DRM_MODE_ATOMIC_ALLOW_MODESET, NULL);
+
+			/* Verify */
+			igt_amd_read_link_settings(data->drm_fd, connector_name,
+						   lane_count, link_rate,
+						   link_spread);
+
+			/* Collect CRC after writing settings */
+			igt_pipe_crc_collect_crc(data->pipe_crc, &crc);
+			igt_assert_crc_equal(&crc, &data->crc_640_480);
+
+			igt_assert(lane_count[current] == lane_count_values[i]);
+			igt_assert(link_rate[current] == link_rate_values[j]);
+
+		}
+	}
+}
+
+static void test_link_training_configs(data_t *data)
+{
+	const drmModeModeInfo *orig_mode;
+	igt_output_t *output;
+	int lane_count[4], link_rate[4], link_spread[4];
+	int orig_lc, orig_lr;
+	const int current = 0;
+
+	igt_enable_connectors(data->drm_fd);
+
+	for_each_connected_output(&data->display, output) {
+		if (!igt_amd_output_has_link_settings(data->drm_fd, output->name)) {
+			igt_info("Skipping output: %s\n", output->name);
+			continue;
+		}
+
+		igt_info("Testing on output: %s\n", output->name);
+
+		/* Init only if display supports link_settings */
+		test_init(data, output);
+
+		orig_mode = igt_output_get_mode(output);
+		igt_assert(orig_mode);
+
+		/* Collect original mode's LC and LR */
+		igt_amd_read_link_settings(data->drm_fd, output->name, lane_count,
+					   link_rate, link_spread);
+		orig_lc = lane_count[current];
+		orig_lr = link_rate[current];
+
+		/* Collect 640x480 CRC */
+		igt_create_pattern_fb(data->drm_fd, mode_640_480.hdisplay,
+				      mode_640_480.vdisplay, DRM_FORMAT_XRGB8888,
+				      0, &data->fb);
+		igt_plane_set_fb(data->primary, &data->fb);
+		igt_display_commit_atomic(&data->display, DRM_MODE_ATOMIC_ALLOW_MODESET, NULL);
+
+		igt_pipe_crc_collect_crc(data->pipe_crc, &data->crc_640_480);
+
+		/* Change link settings. */
+		run_link_training_config(data, output);
+
+		/* Revert mode back. */
+		igt_output_override_mode(output, orig_mode);
+		igt_info("%s: Reverting to lane count: %d, link rate: 0x%02x\n", output->name, orig_lc, orig_lr);
+		igt_amd_write_link_settings(data->drm_fd, output->name, orig_lc, orig_lr,
+					    LINK_TRAINING_DEFAULT);
+
+		igt_display_commit_atomic(&data->display, DRM_MODE_ATOMIC_ALLOW_MODESET, NULL);
+
+		igt_remove_fb(data->drm_fd, &data->fb);
+	}
+
+	test_fini(data);
+}
+
+igt_main
+{
+	data_t data;
+	memset(&data, 0, sizeof(data));
+
+	igt_skip_on_simulation();
+
+	igt_fixture
+	{
+		data.drm_fd = drm_open_driver_master(DRIVER_AMDGPU);
+		if (data.drm_fd == -1)
+			igt_skip("Not an amdgpu driver.\n");
+
+		kmstest_set_vt_graphics_mode();
+
+		igt_display_require(&data.display, data.drm_fd);
+		igt_require(data.display.is_atomic);
+		igt_display_require_output(&data.display);
+	}
+
+	igt_describe("Retrieves all link settings configurations and retrains "
+		     "links on all possible configurations with different "
+		     "types of link training.");
+	igt_subtest("link-training-configs")
+		test_link_training_configs(&data);
+
+	igt_fixture
+	{
+		igt_display_fini(&data.display);
+	}
+}

diff --git a/tests/amdgpu/meson.build b/tests/amdgpu/meson.build
index 805eb299..aec71cb5 100644
--- a/tests/amdgpu/meson.build
+++ b/tests/amdgpu/meson.build

@@ -13,6 +13,7 @@ if libdrm_amdgpu.found()
 			  'amd_prime',
 			  'amd_module_load',
 			  'amd_mem_leak',
+			  'amd_link_settings',
 			  'amd_vrr_range',
 			]
 	amdgpu_deps += libdrm_amdgpu

-- 
2.32.0