[PATCH v2 21/21] drm/i915/dp: Add debugfs entry for link training info

Imre Deak
2024-05-20T18:59:08Z

Add counters for link training pass/failure events and a connector
debugfs entry showing these and relevant link training information. This
is meant to be used by automated testing of the driver's link retraining
and link parameter fallback functionality.

v2:
- Add the entry from intel_dp_link_training.c (Jani)
- Add separate entries for the max link rate/lane count.

Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
.../drm/i915/display/intel_display_types.h | 3 ++
drivers/gpu/drm/i915/display/intel_dp.c | 7 +++-
.../drm/i915/display/intel_dp_link_training.c | 37 +++++++++++++++++++
3 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index 52c69c7eb52f5..6f37f2cca2e99 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1768,6 +1768,9 @@ struct intel_dp {
int requested_lane_count;
int requested_rate;
bool retrain_disabled;
+ int train_count;
+ int retrain_count;
+ int all_train_failures;
/* Sequential link training failures after a passing LT */
int seq_train_failures;
int force_train_failure;
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 895074d548671..0337be8416082 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -2996,6 +2996,9 @@ void intel_dp_reset_link_params(struct intel_dp *intel_dp)
intel_dp->link.max_lane_count = intel_dp_max_common_lane_count(intel_dp);
intel_dp->link.max_rate = intel_dp_max_common_rate(intel_dp);
intel_dp->link.retrain_disabled = false;
+ intel_dp->link.train_count = 0;
+ intel_dp->link.retrain_count = 0;
+ intel_dp->link.all_train_failures = 0;
intel_dp->link.seq_train_failures = 0;
}

@@ -5298,8 +5301,10 @@ int intel_dp_retrain_link(struct intel_encoder *encoder,
}

out:
- if (ret != -EDEADLK)
+ if (ret != -EDEADLK) {
+ intel_dp->link.retrain_count++;
intel_dp->link.force_retrain = false;
+ }

return ret;
}
diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
index 6fac8421a6918..969a5fc4c7b2e 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
@@ -1490,6 +1490,8 @@ void intel_dp_start_link_train(struct intel_atomic_state *state,
else
passed = intel_dp_link_train_all_phys(intel_dp, crtc_state, lttpr_count);

+ intel_dp->link.train_count++;
+
if (intel_dp->link.force_train_failure) {
intel_dp->link.force_train_failure--;
lt_dbg(intel_dp, DP_PHY_DPRX, "Forcing link training failure\n");
@@ -1499,6 +1501,7 @@ void intel_dp_start_link_train(struct intel_atomic_state *state,
return;
}

+ intel_dp->link.all_train_failures++;
intel_dp->link.seq_train_failures++;

/*
@@ -1890,6 +1893,37 @@ DEFINE_DEBUGFS_ATTRIBUTE(i915_dp_force_link_retrain_fops,
i915_dp_force_link_retrain_show,
i915_dp_force_link_retrain_write, "%llu\n");

+static int i915_dp_link_training_info_show(struct seq_file *m, void *data)
+{
+ struct intel_connector *connector = to_intel_connector(m->private);
+ struct drm_i915_private *i915 = to_i915(connector->base.dev);
+ struct intel_dp *intel_dp;
+ int ret;
+
+ ret = drm_modeset_lock_single_interruptible(&i915->drm.mode_config.connection_mutex);
+ if (ret)
+ return ret;
+
+ intel_dp = intel_connector_to_intel_dp(connector);
+
+ seq_printf(m,
+ "retrain_disabled: %s\n"
+ "train_count: %d\n"
+ "retrain_count: %d\n"
+ "all_train_failures: %d\n"
+ "seq_train_failures: %d\n",
+ str_yes_no(intel_dp->link.retrain_disabled),
+ intel_dp->link.train_count,
+ intel_dp->link.retrain_count,
+ intel_dp->link.all_train_failures,
+ intel_dp->link.seq_train_failures);
+
+ drm_modeset_unlock(&i915->drm.mode_config.connection_mutex);
+
+ return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(i915_dp_link_training_info);
+
void intel_dp_link_training_debugfs_add(struct intel_connector *connector)
{
struct dentry *root = connector->base.debugfs_entry;
@@ -1915,4 +1949,7 @@ void intel_dp_link_training_debugfs_add(struct intel_connector *connector)

debugfs_create_file("i915_dp_force_link_retrain", 0644, root,
connector, &i915_dp_force_link_retrain_fops);
+
+ debugfs_create_file("i915_dp_link_training_info", 0444, root,
+ connector, &i915_dp_link_training_info_fops);
}
--
2.43.3