[PATCH i-g-t 1/6] lib/igt_kms: add DP link management helper functions

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

Added helper functions for below
- read current/max link_rate/lane_count
- forcing link retraining
- forcing link training failures
- read pending retrain
- read pending link training failures
- checking output supports forcing lt failures
- force link_rate/lane_count

v2: combine all link training debugfs in one patch (Imre)
    remove unwanted valid output check (Imre)
    return link_rate/lane_count marked with '*' or an error (Imre)

Signed-off-by: Kunal Joshi <kunal1.joshi@intel.com>
---
 lib/igt_kms.c | 210 ++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/igt_kms.h |  10 +++
 2 files changed, 220 insertions(+)

diff --git a/lib/igt_kms.c b/lib/igt_kms.c
index dd530dbab..f0ac1e5dc 100644
--- a/lib/igt_kms.c
+++ b/lib/igt_kms.c
@@ -61,6 +61,7 @@
 #include "sw_sync.h"
 #ifdef HAVE_CHAMELIUM
 #include "igt_chamelium.h"
+#include <ctype.h>
 #endif
 
 /**
@@ -6705,3 +6706,212 @@ int get_num_scalers(igt_display_t *display, enum pipe pipe)
 
 	return num_scalers;
 }
+
+/**
+ * igt_get_dp_link_param_set_for_output:
+ * @drm_fd: A drm file descriptor
+ * @output: Target output
+ * @link_param: 0 for lane count, 1 for link rate
+ *
+ * Returns: link_rate / lane_count if set for output else -1
+ */
+int igt_get_dp_link_param_set_for_output(int drm_fd, igt_output_t *output, int link_param)
+{
+	char *star_ptr, *param_ptr;
+	char buf[512];
+	int dir, res;
+	int ret;
+
+	ret = -1;
+	dir = igt_debugfs_connector_dir(drm_fd, output->name, O_RDONLY);
+	igt_assert_f(dir >= 0, "Failed to open debugfs dir for connector %s\n",
+		     igt_output_name(output));
+	res = igt_debugfs_simple_read(dir, link_param ? "i915_dp_force_link_rate" :
+				      "i915_dp_force_lane_count", buf, sizeof(buf));
+	close(dir);
+	igt_require(res >= 0);
+
+	/*
+	 * Check we have a mode enabled for the output
+	 * If so we will have current  active link rate
+	 * marked with a *
+	 */
+	star_ptr = strstr(buf, "*");
+
+	if (star_ptr) {
+		param_ptr = star_ptr - 1;
+		while (param_ptr > buf && isdigit(*param_ptr))
+			param_ptr--;
+
+		param_ptr++;
+		igt_assert(sscanf(param_ptr, "%d", &ret) == 1);
+	}
+	return ret;
+}
+
+/**
+ * igt_get_dp_max_link_param:
+ * @drm_fd: A drm file descriptor
+ * @output: The output to query
+ * @link_param: 0 for lane count, 1 for link rate
+ *
+ * Get the max link_rate / lane_count supported by the sink.
+ *
+ * Returns: max link_rate / lane_count supported by the sink.
+ */
+int igt_get_dp_max_link_param(int drm_fd, igt_output_t *output, int link_param)
+{
+	char buf[512];
+	int dir, res;
+	int max_link_param;
+
+	dir = igt_debugfs_connector_dir(drm_fd, output->name, O_DIRECTORY);
+	igt_assert_f(dir >= 0, "Failed to open debugfs dir for connector %s\n",
+				 igt_output_name(output));
+	res = igt_debugfs_simple_read(dir, link_param ? "i915_dp_max_link_rate" :
+				      "i915_dp_max_lane_count", buf, sizeof(buf));
+	close(dir);
+	igt_require_f(res >= 0, "Couldn't read i915_dp_max_link_rate");
+
+	igt_assert(sscanf(buf, "%d", &max_link_param) == 1);
+
+	return max_link_param;
+}
+
+/**
+ * igt_force_link_retrain:
+ * @drm_fd: A drm file descriptor
+ * @output: Target output
+ * @retrain_count: number of retraining required
+ *
+ * Force link retrain on the output.
+ */
+void igt_force_link_retrain(int drm_fd, igt_output_t *output, int retrain_count)
+{
+	int dir;
+	char value[2];
+
+	snprintf(value, sizeof(value), "%d", retrain_count);
+	dir = igt_debugfs_connector_dir(drm_fd, output->name, O_RDONLY);
+	igt_assert_f(dir >= 0, "Failed to open debugfs dir for connector %s\n",
+			       igt_output_name(output));
+	igt_sysfs_write(dir, "i915_dp_force_link_retrain", value, sizeof(value));
+	close(dir);
+}
+
+/**
+ * igt_force_lt_failure:
+ * @drm_fd: A drm file descriptor
+ * @output: Target output
+ * @failure_count: 1 for same link param and
+ *                2 for reduced link params
+ *
+ * Force link training failure on the output.
+ * @failure_count: 1 for retraining with same link params
+ *				   2 for retraining with reduced link params
+ */
+void igt_force_lt_failure(int drm_fd, igt_output_t *output, int failure_count)
+{
+	int dir;
+	char value[2];
+
+	snprintf(value, sizeof(value), "%d", failure_count);
+	dir = igt_debugfs_connector_dir(drm_fd, output->name, O_RDONLY);
+	igt_assert_f(dir >= 0, "Failed to open debugfs dir for connector %s\n",
+			       igt_output_name(output));
+	igt_sysfs_write(dir, "i915_dp_force_link_training_failure",
+			     value, sizeof(value));
+	close(dir);
+}
+
+/**
+ * igt_get_dp_link_retrain_disabled:
+ * @drm_fd: A drm file descriptor
+ * @output: Target output
+ *
+ * Returns: True if link retrain disabled, false otherwise
+ */
+bool igt_get_dp_link_retrain_disabled(int drm_fd, igt_output_t *output)
+{
+	int dir, res;
+	char buf[512];
+
+	dir = igt_debugfs_connector_dir(drm_fd, output->name, O_RDONLY);
+	igt_assert_f(dir >= 0, "Failed to open debugfs dir for connector %s\n",
+			       igt_output_name(output));
+	res = igt_debugfs_simple_read(dir,
+				      "i915_dp_link_retrain_disabled",
+				      buf, sizeof(buf));
+	close(dir);
+	igt_require(res >= 0);
+	return strstr(buf, "yes");
+}
+
+/**
+ * Checks if the force link training failure debugfs
+ * is available for a specific output.
+ *
+ * @drmfd: file descriptor of the DRM device.
+ * @output: output to check.
+ * Returns:
+ *  true if the debugfs is available, false otherwise.
+ */
+bool igt_has_force_link_training_failure_debugfs(int drmfd, igt_output_t *output)
+{
+	int debugfs_fd, ret;
+	char buf[512];
+
+	igt_assert_f(output->name, "Invalid output\n");
+	debugfs_fd = igt_debugfs_connector_dir(drmfd, output->name, O_RDONLY);
+	if (debugfs_fd < 0)
+		return false;
+	ret = igt_debugfs_simple_read(debugfs_fd,
+				      "i915_dp_force_link_training_failure",
+				      buf, sizeof(buf));
+	close(debugfs_fd);
+	return ret >= 0;
+}
+
+/**
+ * igt_get_dp_pending_lt_failures:
+ * @drm_fd: A drm file descriptor
+ * @output: Target output
+ *
+ * Returns: Number of pending link training failures.
+ */
+int igt_get_dp_pending_lt_failures(int drm_fd, igt_output_t *output)
+{
+	int dir, res, ret;
+	char buf[512];
+
+	dir = igt_debugfs_connector_dir(drm_fd, output->name, O_RDONLY);
+	igt_assert_f(dir >= 0, "Failed to open debugfs dir for connector %s\n",
+			       igt_output_name(output));
+	res = igt_debugfs_simple_read(dir, "i915_dp_force_link_training_failure", buf, sizeof(buf));
+	close(dir);
+	igt_require(res >= 0);
+	sscanf(buf, "%d", &ret);
+	return ret;
+}
+
+/**
+ * igt_dp_pending_retrain:
+ * @drm_fd: A drm file descriptor
+ * @output: Target output
+ *
+ * Returns: Number of pending link retrains.
+ */
+int igt_get_dp_pending_retrain(int drm_fd, igt_output_t *output)
+{
+	int dir, res, ret;
+	char buf[512];
+
+	dir = igt_debugfs_connector_dir(drm_fd, output->name, O_RDONLY);
+	igt_assert_f(dir >= 0, "Failed to open debugfs dir for connector %s\n",
+			       igt_output_name(output));
+	res = igt_debugfs_simple_read(dir, "i915_dp_force_link_retrain", buf, sizeof(buf));
+	close(dir);
+	igt_require(res >= 0);
+	sscanf(buf, "%d", &ret);
+	return ret;
+}
diff --git a/lib/igt_kms.h b/lib/igt_kms.h
index 25ba50916..895bc9d04 100644
--- a/lib/igt_kms.h
+++ b/lib/igt_kms.h
@@ -1224,5 +1224,15 @@ bool intel_pipe_output_combo_valid(igt_display_t *display);
 bool igt_check_output_is_dp_mst(igt_output_t *output);
 int igt_get_dp_mst_connector_id(igt_output_t *output);
 int get_num_scalers(igt_display_t *display, enum pipe pipe);
+int igt_get_dp_link_param_set_for_output(int drm_fd, igt_output_t *output,
+					 int link_param);
+int igt_get_dp_max_link_param(int drm_fd, igt_output_t *output,
+			      int link_param);
+void igt_force_link_retrain(int drm_fd, igt_output_t *output, int retrain_count);
+void igt_force_lt_failure(int drm_fd, igt_output_t *output, int failure_count);
+bool igt_get_dp_link_retrain_disabled(int drm_fd, igt_output_t *output);
+bool igt_has_force_link_training_failure_debugfs(int drmfd, igt_output_t *output);
+int igt_get_dp_pending_lt_failures(int drm_fd, igt_output_t *output);
+int igt_get_dp_pending_retrain(int drm_fd, igt_output_t *output);
 
 #endif /* __IGT_KMS_H__ */
-- 
2.43.0