On Tue, Sep 22, 2020 at 03:51:02PM +0300, Imre Deak wrote:
> Split the prepare, link training, fallback-handling steps into their own
> functions for clarity and as a preparation for the upcoming LTTPR changes.
>
> While at it also add some documentation to exported functions.
>
> Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
> ---
> .../drm/i915/display/intel_dp_link_training.c | 80 ++++++++++++++-----
> 1 file changed, 62 insertions(+), 18 deletions(-)
>
> 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 6d13d00db5e6..0c3809891bd2 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> @@ -162,14 +162,13 @@ static bool intel_dp_link_max_vswing_reached(struct intel_dp *intel_dp)
> return true;
> }
>
> -/* Enable corresponding port and start training pattern 1 */
> -static bool
> -intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp)
> +/*
> + * Prepare link training by configuring the link parameters and enabling the
> + * corresponding port.
> + */
> +static void intel_dp_prepare_link_train(struct intel_dp *intel_dp)
> {
> struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> - u8 voltage;
> - int voltage_tries, cr_tries, max_cr_tries;
> - bool max_vswing_reached = false;
> u8 link_config[2];
> u8 link_bw, rate_select;
>
> @@ -203,6 +202,16 @@ intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp)
> drm_dp_dpcd_write(&intel_dp->aux, DP_DOWNSPREAD_CTRL, link_config, 2);
>
> intel_dp->DP |= DP_PORT_EN;
I guess we no longer actually enable the port here? The comment ^ still says
we do.
Hmm. Seems we do enable the port on ddi platforms, but not on older
platforms. I guess the docs could still use a tweak to reflect
reality a bit better.
> +}
> +
> +/* Perform the link training clock recovery phase using training pattern 1. */
> +static bool
> +intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp)
> +{
> + struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> + u8 voltage;
> + int voltage_tries, cr_tries, max_cr_tries;
> + bool max_vswing_reached = false;
>
> /* clock recovery */
> if (!intel_dp_reset_link_train(intel_dp,
> @@ -325,6 +334,10 @@ static u32 intel_dp_training_pattern(struct intel_dp *intel_dp)
> return DP_TRAINING_PATTERN_2;
> }
>
> +/*
> + * Perform the link training channel equalization phase using one of training
> + * pattern 2, 3 or 4 depending on the the source and sink capabilities.
> + */
> static bool
> intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
> {
> @@ -395,6 +408,15 @@ intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
>
> }
>
> +/**
> + * intel_dp_stop_link_train - stop link training
> + * @intel_dp: DP struct
> + *
> + * Stop the link training of the @intel_dp port, programming the port to
> + * output an idle pattern
I don't think we use the idle pattern on all platforms.
BTW intel_dp_set_idle_link_train() looks pretty pointless. Could just
inline it into its only caller, or at least move it into
intel_dp_link_training.c.
Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> on the link and disabling the training pattern in
> + * the sink's DPCD.
> + * This function must be called after intel_dp_start_link_train().
> + */
> void intel_dp_stop_link_train(struct intel_dp *intel_dp)
> {
> intel_dp->link_trained = true;
> @@ -403,30 +425,37 @@ void intel_dp_stop_link_train(struct intel_dp *intel_dp)
> DP_TRAINING_PATTERN_DISABLE);
> }
>
> -void
> -intel_dp_start_link_train(struct intel_dp *intel_dp)
> +static bool
> +intel_dp_link_train(struct intel_dp *intel_dp)
> {
> struct intel_connector *intel_connector = intel_dp->attached_connector;
> + bool ret = false;
> +
> + intel_dp_prepare_link_train(intel_dp);
>
> if (!intel_dp_link_training_clock_recovery(intel_dp))
> - goto failure_handling;
> + goto out;
> +
> if (!intel_dp_link_training_channel_equalization(intel_dp))
> - goto failure_handling;
> + goto out;
>
> - drm_dbg_kms(&dp_to_i915(intel_dp)->drm,
> - "[CONNECTOR:%d:%s] Link Training Passed at Link Rate = %d, Lane count = %d",
> - intel_connector->base.base.id,
> - intel_connector->base.name,
> - intel_dp->link_rate, intel_dp->lane_count);
> - return;
> + ret = true;
>
> - failure_handling:
> +out:
> drm_dbg_kms(&dp_to_i915(intel_dp)->drm,
> - "[CONNECTOR:%d:%s] Link Training failed at link rate = %d, lane count = %d",
> + "[CONNECTOR:%d:%s] Link Training %s at Link Rate = %d, Lane count = %d",
> intel_connector->base.base.id,
> intel_connector->base.name,
> + ret ? "passed" : "failed",
> intel_dp->link_rate, intel_dp->lane_count);
>
> + return ret;
> +}
> +
> +static void intel_dp_schedule_fallback_link_training(struct intel_dp *intel_dp)
> +{
> + struct intel_connector *intel_connector = intel_dp->attached_connector;
> +
> if (intel_dp->hobl_active) {
> drm_dbg_kms(&dp_to_i915(intel_dp)->drm,
> "Link Training failed with HOBL active, not enabling it from now on");
> @@ -440,3 +469,18 @@ intel_dp_start_link_train(struct intel_dp *intel_dp)
> /* Schedule a Hotplug Uevent to userspace to start modeset */
> schedule_work(&intel_connector->modeset_retry_work);
> }
> +
> +/**
> + * intel_dp_start_link_train - start link training
> + * @intel_dp: DP struct
> + *
> + * Start the link training of the @intel_dp port, scheduling a fallback
> + * retraining with reduced link rate/lane parameters if the link training
> + * fails.
> + * After calling this function intel_dp_stop_link_train() must be called.
> + */
> +void intel_dp_start_link_train(struct intel_dp *intel_dp)
> +{
> + if (!intel_dp_link_train(intel_dp))
> + intel_dp_schedule_fallback_link_training(intel_dp);
> +}
> --
> 2.17.1
>
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--
Ville Syrjälä
Intel
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