[Intel-gfx] [RFC 4/5] drm/i915: Link Rate fallback on Link training failure
Manasi Navare
manasi.d.navare at intel.com
Fri Oct 7 22:46:35 UTC 2016
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 and use a lower link rate
to prune the modes during the next modeset, configure the pipe at
lower link rate and retrian at lower link rate.
This is also required to pass DP CTS tests 4.3.1.3, 4.3.1.4,
4.3.1.6.
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_ddi.c | 10 ++++++++-
drivers/gpu/drm/i915/intel_dp.c | 31 ++++++++++++++++++++++++---
drivers/gpu/drm/i915/intel_dp_link_training.c | 12 ++++++++---
drivers/gpu/drm/i915/intel_drv.h | 6 +++++-
4 files changed, 51 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 35f0b7c..d3b5671 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1652,7 +1652,15 @@ static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
intel_prepare_dp_ddi_buffers(encoder);
intel_ddi_init_dp_buf_reg(encoder);
intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
- intel_dp_start_link_train(intel_dp);
+ if (!intel_dp_start_link_train(intel_dp)) {
+ DRM_ERROR("Link Training failed at link rate = %d, lane count = %d",
+ link_rate, lane_count);
+ intel_dp->link_train_failed = true;
+ intel_dp->link_train_failed_link_rate = link_rate;
+ intel_dp->link_train_failed_lane_count = lane_count;
+ /* Schedule a Hotplug Uevent to userspace to start modeset */
+ schedule_work(&dev_priv->i915_modeset_retry_work);
+ }
if (port != PORT_A || INTEL_GEN(dev_priv) >= 9)
intel_dp_stop_link_train(intel_dp);
}
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 610316f..4779742 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -313,6 +313,7 @@ intel_dp_mode_valid(struct drm_connector *connector,
int target_clock = mode->clock;
int max_rate, mode_rate, max_lanes, max_link_clock;
int max_dotclk;
+ int common_rates[DP_MAX_SUPPORTED_RATES] = {};
max_dotclk = intel_dp_downstream_max_dotclock(intel_dp);
@@ -326,8 +327,22 @@ intel_dp_mode_valid(struct drm_connector *connector,
target_clock = fixed_mode->clock;
}
- max_link_clock = intel_dp_max_link_rate(intel_dp);
- max_lanes = intel_dp_max_lane_count(intel_dp);
+ /* Prune the modes based on the link rate that failed */
+ if (intel_dp->link_train_failed_link_rate) {
+ intel_dp->link_rate_index = intel_dp_link_rate_index(intel_dp,
+ common_rates,
+ intel_dp->link_train_failed_link_rate);
+ if (intel_dp->link_rate_index > 0) {
+ max_link_clock = common_rates[intel_dp->link_rate_index - 1];
+ max_lanes = intel_dp_max_lane_count(intel_dp);
+ } else
+ /* Here we can lower the lane count, but that is DP 1.3 not 1.2 */
+ DRM_ERROR(" No Valid Mode Supported for this Link");
+ }
+ else {
+ max_link_clock = intel_dp_max_link_rate(intel_dp);
+ max_lanes = intel_dp_max_lane_count(intel_dp);
+ }
max_rate = intel_dp_max_data_rate(max_link_clock, max_lanes);
mode_rate = intel_dp_link_required(target_clock, 18);
@@ -1623,6 +1638,14 @@ intel_dp_compute_config(struct intel_encoder *encoder,
intel_dp->compliance_test_lane_count = 0;
}
+ /* Fall back to lower link rate in case of failure in previous modeset */
+ if (intel_dp->link_train_failed_link_rate) {
+ min_lane_count = max_lane_count;
+ min_clock = max_clock = intel_dp->link_rate_index - 1;
+ intel_dp->link_train_failed_link_rate = 0;
+ intel_dp->link_rate_index = -1;
+ }
+
DRM_DEBUG_KMS("DP link computation with max lane count %i "
"max bw %d pixel clock %iKHz\n",
max_lane_count, common_rates[max_clock],
@@ -4412,9 +4435,11 @@ intel_dp_long_pulse(struct intel_connector *intel_connector)
/* Can't disconnect eDP, but you can close the lid... */
if (is_edp(intel_dp))
status = edp_detect(intel_dp);
- else if (intel_dp->compliance_test_type == DP_TEST_LINK_TRAINING) {
+ else if (intel_dp->compliance_test_type == DP_TEST_LINK_TRAINING ||
+ intel_dp->link_train_failed) {
status = connector_status_disconnected;
intel_dp->compliance_test_type = 0;
+ intel_dp->link_train_failed = false;
goto out;
}
else if (intel_digital_port_connected(to_i915(dev),
diff --git a/drivers/gpu/drm/i915/intel_dp_link_training.c b/drivers/gpu/drm/i915/intel_dp_link_training.c
index 0048b52..10f81ab 100644
--- a/drivers/gpu/drm/i915/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/intel_dp_link_training.c
@@ -310,9 +310,15 @@ void intel_dp_stop_link_train(struct intel_dp *intel_dp)
DP_TRAINING_PATTERN_DISABLE);
}
-void
+bool
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);
+ bool ret;
+
+ if (intel_dp_link_training_clock_recovery(intel_dp)) {
+ ret = intel_dp_link_training_channel_equalization(intel_dp);
+ if (ret)
+ return true;
+ }
+ return false;
}
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 82fc4fe..10335ab 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -882,6 +882,10 @@ struct intel_dp {
uint32_t DP;
int link_rate;
uint8_t lane_count;
+ int link_train_failed_link_rate;
+ uint8_t link_train_failed_lane_count;
+ int link_rate_index;
+ bool link_train_failed;
uint8_t sink_count;
bool link_mst;
bool has_audio;
@@ -1389,7 +1393,7 @@ bool intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
void intel_dp_set_link_params(struct intel_dp *intel_dp,
int link_rate, uint8_t lane_count,
bool link_mst);
-void intel_dp_start_link_train(struct intel_dp *intel_dp);
+bool intel_dp_start_link_train(struct intel_dp *intel_dp);
void intel_dp_stop_link_train(struct intel_dp *intel_dp);
void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode);
void intel_dp_encoder_reset(struct drm_encoder *encoder);
--
1.9.1
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