From 9301397a63b3bf1090dffe846c6f1c8efa032236 Mon Sep 17 00:00:00 2001 From: Manasi Navare Date: Thu, 6 Apr 2017 16:44:19 +0300 Subject: [PATCH] drm/i915: Implement Link Rate fallback on Link training failure If link training at a link rate optimal for a particular mode fails during modeset's atomic commit phase, then we let the modeset complete and then retry. We save the link rate value at which link training failed, update the link status property to "BAD" and use a lower link rate to prune the modes. It will redo the modeset on the current mode at lower link rate or if the current mode gets pruned due to lower link constraints then, it will send a hotplug uevent for userspace to handle it. This is also required to pass DP CTS tests 4.3.1.3, 4.3.1.4, 4.3.1.6. This patch is a resend of the original commit id (233ce881dd91fb "drm/i915: Implement Link Rate fallback on Link training failure") which got reverted in this commit id (afc1ebf4562a14 Revert "drm/i915: Implement Link Rate fallback on Link training failure") due to CI failures. After investigating the CI failures it was found that these were essentially the failures which were always there but hidden because they used to be DRM_DEBUG_KMS messages for link failures so never got caught by CI. But now this patch actually throws DRM_ERROR if the link training fails at RBR and 1 lane. So it caught these link train failures. There were two failures: 1. On SKL 6700k this was because the machine in CI lab is a SKL desktop without eDP on Port A. But our VBT initialization code in the driver writes VBT defaults in a way that it always sets DP flag on Port A and this does not get cleared after parsing the VBT outputs. This has been fixed in commit id (bb1d132935c2f8 "drm/i915/vbt: split out defaults that are set when there is no VBT) and (665788572c6410b "drm/i915/vbt: don't propagate errors from intel_bios_init()) 2. On ILK-650 desktop - This was happening because of a bad monitor desktop combination. I switched the monitor in the CI lab and that helped get rid of the link failures on ILK system. v10: * Rebase on drm-tip and resend after revert v9: * Use the trimmed max values of link rate/lane count based on link train fallback (Daniel Vetter) v8: * Set link_status to BAD first and then call mode_valid (Jani Nikula) v7: Remove the redundant variable in previous patch itself v6: * Obtain link rate index from fallback_link_rate using the helper intel_dp_link_rate_index (Jani Nikula) * Include fallback within intel_dp_start_link_train (Jani Nikula) v5: * Move set link status to drm core (Daniel Vetter, Jani Nikula) v4: * Add fallback support for non DDI platforms too * Set connector->link status inside set_link_status function (Jani Nikula) v3: * Set link status property to BAd unconditionally (Jani Nikula) * Dont use two separate variables link_train_failed and link_status to indicate same thing (Jani Nikula) v2: * Squashed a few patches (Jani Nikula) Acked-by: Tony Cheng Acked-by: Harry Wentland Cc: Jani Nikula Cc: Daniel Vetter Cc: Ville Syrjala Signed-off-by: Manasi Navare Reviewed-by: Jani Nikula Signed-off-by: Jani Nikula Link: http://patchwork.freedesktop.org/patch/msgid/16ca48b1e74c618929245e9a085b9e3483c3a16d.1491485983.git.jani.nikula@intel.com --- drivers/gpu/drm/i915/intel_dp.c | 27 +++++++++++++++++++ drivers/gpu/drm/i915/intel_dp_link_training.c | 22 +++++++++++++-- drivers/gpu/drm/i915/intel_drv.h | 3 +++ 3 files changed, 50 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 09601a22d3cc..08834f74d396 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -5981,6 +5981,29 @@ intel_dp_init_connector_port_info(struct intel_digital_port *intel_dig_port) } } +static void intel_dp_modeset_retry_work_fn(struct work_struct *work) +{ + struct intel_connector *intel_connector; + struct drm_connector *connector; + + intel_connector = container_of(work, typeof(*intel_connector), + modeset_retry_work); + connector = &intel_connector->base; + DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n", connector->base.id, + connector->name); + + /* Grab the locks before changing connector property*/ + mutex_lock(&connector->dev->mode_config.mutex); + /* Set connector link status to BAD and send a Uevent to notify + * userspace to do a modeset. + */ + drm_mode_connector_set_link_status_property(connector, + DRM_MODE_LINK_STATUS_BAD); + mutex_unlock(&connector->dev->mode_config.mutex); + /* Send Hotplug uevent so userspace can reprobe */ + drm_kms_helper_hotplug_event(connector->dev); +} + bool intel_dp_init_connector(struct intel_digital_port *intel_dig_port, struct intel_connector *intel_connector) @@ -5993,6 +6016,10 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port, enum port port = intel_dig_port->port; int type; + /* Initialize the work for modeset in case of link train failure */ + INIT_WORK(&intel_connector->modeset_retry_work, + intel_dp_modeset_retry_work_fn); + if (WARN(intel_dig_port->max_lanes < 1, "Not enough lanes (%d) for DP on port %c\n", intel_dig_port->max_lanes, port_name(port))) diff --git a/drivers/gpu/drm/i915/intel_dp_link_training.c b/drivers/gpu/drm/i915/intel_dp_link_training.c index 694ad0ffb523..b79c1c0e404c 100644 --- a/drivers/gpu/drm/i915/intel_dp_link_training.c +++ b/drivers/gpu/drm/i915/intel_dp_link_training.c @@ -314,6 +314,24 @@ void intel_dp_stop_link_train(struct intel_dp *intel_dp) void intel_dp_start_link_train(struct intel_dp *intel_dp) { - intel_dp_link_training_clock_recovery(intel_dp); - intel_dp_link_training_channel_equalization(intel_dp); + struct intel_connector *intel_connector = intel_dp->attached_connector; + + if (!intel_dp_link_training_clock_recovery(intel_dp)) + goto failure_handling; + if (!intel_dp_link_training_channel_equalization(intel_dp)) + goto failure_handling; + + DRM_DEBUG_KMS("Link Training Passed at Link Rate = %d, Lane count = %d", + intel_dp->link_rate, intel_dp->lane_count); + return; + + failure_handling: + DRM_DEBUG_KMS("Link Training failed at link rate = %d, lane count = %d", + intel_dp->link_rate, intel_dp->lane_count); + if (!intel_dp_get_link_train_fallback_values(intel_dp, + intel_dp->link_rate, + intel_dp->lane_count)) + /* Schedule a Hotplug Uevent to userspace to start modeset */ + schedule_work(&intel_connector->modeset_retry_work); + return; } diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h index f78d7c5f3805..100750c878e1 100644 --- a/drivers/gpu/drm/i915/intel_drv.h +++ b/drivers/gpu/drm/i915/intel_drv.h @@ -321,6 +321,9 @@ struct intel_connector { void *port; /* store this opaque as its illegal to dereference it */ struct intel_dp *mst_port; + + /* Work struct to schedule a uevent on link train failure */ + struct work_struct modeset_retry_work; }; struct dpll { -- 2.20.1