[PATCH 4/4] drm/i915: Implement Link Rate fallback on Link training failure
Manasi Navare
manasi.d.navare at intel.com
Thu Dec 8 18:23:58 UTC 2016
Hi Jani,
Could you please review this patch?
This patch was changed a bit from the last time you reviewed it
based on feedback from Sean Paul that the driver need not
validate the modes and prune the mode on link training failure.
Instead it should just send the hotplug uevent after setting link status
to BAD and then userspace driver should take care of validating the modes
again before modeset. So the i915_modeset_work_fn removed the calls to
intel_dp_mode_valid() and prune_mode_invalid().
There are no other functional changes in this patch from the previous
reviewed version.
Daniel has already ACKED this, but need your formal r-b.
Regards
Manasi
On Mon, Dec 05, 2016 at 04:27:38PM -0800, Manasi Navare wrote:
> 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.
>
> 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 <tony.cheng at amd.com>
> Acked-by: Harry Wentland <Harry.wentland at amd.com>
> Cc: Jani Nikula <jani.nikula at linux.intel.com>
> Cc: Daniel Vetter <daniel.vetter at intel.com>
> Cc: Ville Syrjala <ville.syrjala at linux.intel.com>
> Signed-off-by: Manasi Navare <manasi.d.navare at 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 b5c7526f..404da32 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -5676,6 +5676,29 @@ static bool intel_edp_init_connector(struct intel_dp *intel_dp,
> return false;
> }
>
> +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)
> @@ -5688,6 +5711,10 @@ static bool intel_edp_init_connector(struct intel_dp *intel_dp,
> 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 0048b52..955b239 100644
> --- a/drivers/gpu/drm/i915/intel_dp_link_training.c
> +++ b/drivers/gpu/drm/i915/intel_dp_link_training.c
> @@ -313,6 +313,24 @@ 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 47e3671..9d6f7ee 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -315,6 +315,9 @@ 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 {
> --
> 1.9.1
>
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