drm/i915/dp: Add debugfs entry to force link retrain

Add a connector debugfs entry to force retrain an active link. This can
be used to test both custom link parameters (previously forced via the
force_link_rate/lane_count entries) or link train failure scenarios
(previously forced via the force_link_training_failure entry). The entry
will autoreset after the link-retrain is complete.

v2: Add the entry from intel_dp_link_training.c (Jani)
v3: Lock connection_mutex only for the required intel_dp state. (Ville)

Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610164933.2947366-21-imre.deak@intel.com

diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index 9ae22e8dd2e273246efd3c5b708b09511f8486f9..02ebe6f3e765df34d0e8d894ae41bedc0f7be1e6 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1777,6 +1777,7 @@ struct intel_dp {
                /* Sequential link training failures after a passing LT */
                int seq_train_failures;
                int force_train_failure;
+               bool force_retrain;
        } link;
        bool reset_link_params;
        int mso_link_count;

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 1fa6f50213e9b1ed3ca36250f3d2c5716894a32f..9a9bb0f5b7fe064b1b79bfd3941d4aa0a6c0b7d4 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -5065,7 +5065,7 @@ intel_dp_check_mst_status(struct intel_dp *intel_dp)
                        drm_dp_mst_hpd_irq_send_new_request(&intel_dp->mst_mgr);
        }
 
-       if (!link_ok)
+       if (!link_ok || intel_dp->link.force_retrain)
                intel_encoder_link_check_queue_work(encoder, 0);
 
        return !reprobe_needed;
@@ -5114,6 +5114,9 @@ intel_dp_needs_link_retrain(struct intel_dp *intel_dp)
        if (intel_psr_enabled(intel_dp))
                return false;
 
+       if (intel_dp->link.force_retrain)
+               return true;
+
        if (drm_dp_dpcd_read_phy_link_status(&intel_dp->aux, DP_PHY_DPRX,
                                             link_status) < 0)
                return false;
@@ -5252,8 +5255,9 @@ static int intel_dp_retrain_link(struct intel_encoder *encoder,
        if (!intel_dp_needs_link_retrain(intel_dp))
                return 0;
 
-       drm_dbg_kms(&dev_priv->drm, "[ENCODER:%d:%s] retraining link\n",
-                   encoder->base.base.id, encoder->base.name);
+       drm_dbg_kms(&dev_priv->drm, "[ENCODER:%d:%s] retraining link (forced %s)\n",
+                   encoder->base.base.id, encoder->base.name,
+                   str_yes_no(intel_dp->link.force_retrain));
 
        for_each_intel_crtc_in_pipe_mask(&dev_priv->drm, crtc, pipe_mask) {
                const struct intel_crtc_state *crtc_state =
@@ -5281,7 +5285,7 @@ static int intel_dp_retrain_link(struct intel_encoder *encoder,
                                    encoder->base.base.id, encoder->base.name,
                                    ERR_PTR(ret));
 
-               return ret;
+               goto out;
        }
 
        for_each_intel_crtc_in_pipe_mask(&dev_priv->drm, crtc, pipe_mask) {
@@ -5308,7 +5312,11 @@ static int intel_dp_retrain_link(struct intel_encoder *encoder,
                                                              intel_crtc_pch_transcoder(crtc), true);
        }
 
-       return 0;
+out:
+       if (ret != -EDEADLK)
+               intel_dp->link.force_retrain = false;
+
+       return ret;
 }
 
 void intel_dp_link_check(struct intel_encoder *encoder)

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 a6ea92b54c2f4ef34e4bd0c9d9fe2d85fc31c3a1..4da550d6e0ffc0ac7ba2a9b45a977511369dc0cf 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
@@ -26,6 +26,7 @@
 #include "intel_dp.h"
 #include "intel_dp_link_training.h"
 #include "intel_encoder.h"
+#include "intel_hotplug.h"
 #include "intel_panel.h"
 
 #define LT_MSG_PREFIX                  "[CONNECTOR:%d:%s][ENCODER:%d:%s][%s] "
@@ -1856,6 +1857,47 @@ 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");
 
+static int i915_dp_force_link_retrain_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 = intel_connector_to_intel_dp(connector);
+       int err;
+
+       err = drm_modeset_lock_single_interruptible(&i915->drm.mode_config.connection_mutex);
+       if (err)
+               return err;
+
+       *val = intel_dp->link.force_retrain;
+
+       drm_modeset_unlock(&i915->drm.mode_config.connection_mutex);
+
+       return 0;
+}
+
+static int i915_dp_force_link_retrain_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 = intel_connector_to_intel_dp(connector);
+       int err;
+
+       err = drm_modeset_lock_single_interruptible(&i915->drm.mode_config.connection_mutex);
+       if (err)
+               return err;
+
+       intel_dp->link.force_retrain = val;
+
+       drm_modeset_unlock(&i915->drm.mode_config.connection_mutex);
+
+       intel_hpd_trigger_irq(dp_to_dig_port(intel_dp));
+
+       return 0;
+}
+DEFINE_DEBUGFS_ATTRIBUTE(i915_dp_force_link_retrain_fops,
+                        i915_dp_force_link_retrain_show,
+                        i915_dp_force_link_retrain_write, "%llu\n");
+
 void intel_dp_link_training_debugfs_add(struct intel_connector *connector)
 {
        struct dentry *root = connector->base.debugfs_entry;
@@ -1878,4 +1920,7 @@ void intel_dp_link_training_debugfs_add(struct intel_connector *connector)
 
        debugfs_create_file("i915_dp_force_link_training_failure", 0644, root,
                            connector, &i915_dp_force_link_training_failure_fops);
+
+       debugfs_create_file("i915_dp_force_link_retrain", 0644, root,
+                           connector, &i915_dp_force_link_retrain_fops);
 }