[PATCH v2 19/21] drm/i915/dp: Add debugfs entry to force link training failure

Imre Deak
2024-05-20T18:58:43Z

Add a connector debugfs entry to force a failure during the following
1-2 link training. The entry will auto-reset after the specified link
training events are complete.

v2: Add the entry from intel_dp_link_training.c (Jani)

Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
.../drm/i915/display/intel_display_types.h | 1 +
.../drm/i915/display/intel_dp_link_training.c | 52 ++++++++++++++++++-
2 files changed, 52 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 e1c41cece249d..dbe1468fe471d 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1770,6 +1770,7 @@ struct intel_dp {
bool retrain_disabled;
/* Sequential link training failures after a passing LT */
int seq_train_failures;
+ int force_train_failure;
} link;
bool reset_link_params;
int mso_link_count;
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 764187bc42ff9..b40148a42f442 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
@@ -1489,7 +1489,10 @@ 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);

- if (passed) {
+ 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");
+ } else if (passed) {
intel_dp->link.seq_train_failures = 0;
intel_ddi_queue_link_check(dig_port, 2000);
return;
@@ -1799,6 +1802,50 @@ static int i915_dp_max_lane_count_show(void *data, u64 *val)
}
DEFINE_DEBUGFS_ATTRIBUTE(i915_dp_max_lane_count_fops, i915_dp_max_lane_count_show, NULL, "%llu\n");

+static int i915_dp_force_link_training_failure_show(void *data, u64 *val)
+{
+ struct intel_connector *connector = to_intel_connector(data);
+ struct drm_i915_private *i915 = to_i915(connector->base.dev);
+ struct intel_dp *intel_dp;
+ int err;
+
+ err = drm_modeset_lock_single_interruptible(&i915->drm.mode_config.connection_mutex);
+ if (err)
+ return err;
+
+ intel_dp = intel_connector_to_intel_dp(connector);
+ *val = intel_dp->link.force_train_failure;
+
+ drm_modeset_unlock(&i915->drm.mode_config.connection_mutex);
+
+ return 0;
+}
+
+static int i915_dp_force_link_training_failure_write(void *data, u64 val)
+{
+ struct intel_connector *connector = to_intel_connector(data);
+ struct drm_i915_private *i915 = to_i915(connector->base.dev);
+ struct intel_dp *intel_dp;
+ int err;
+
+ if (val > 2)
+ return -EINVAL;
+
+ err = drm_modeset_lock_single_interruptible(&i915->drm.mode_config.connection_mutex);
+ if (err)
+ return err;
+
+ intel_dp = intel_connector_to_intel_dp(connector);
+ intel_dp->link.force_train_failure = val;
+
+ drm_modeset_unlock(&i915->drm.mode_config.connection_mutex);
+
+ return 0;
+}
+DEFINE_DEBUGFS_ATTRIBUTE(i915_dp_force_link_training_failure_fops,
+ i915_dp_force_link_training_failure_show,
+ i915_dp_force_link_training_failure_write, "%llu\n");
+
void intel_dp_link_training_debugfs_add(struct intel_connector *connector)
{
struct dentry *root = connector->base.debugfs_entry;
@@ -1818,4 +1865,7 @@ void intel_dp_link_training_debugfs_add(struct intel_connector *connector)

debugfs_create_file("i915_dp_max_lane_count", 0444, root,
connector, &i915_dp_max_lane_count_fops);
+
+ debugfs_create_file("i915_dp_force_link_training_failure", 0644, root,
+ connector, &i915_dp_force_link_training_failure_fops);
}
--
2.43.3