[PATCH RFC 7/8] drm/i915: Link Rate fallback on Link training failure
Manasi Navare
manasi.d.navare at intel.com
Wed Oct 19 21:46:23 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 | 14 ++++++++++-
drivers/gpu/drm/i915/intel_dp.c | 35 +++++++++++++++++++++++++--
drivers/gpu/drm/i915/intel_dp_link_training.c | 12 ++++++---
drivers/gpu/drm/i915/intel_drv.h | 6 ++++-
4 files changed, 60 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 7f7741c..cccb301 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1642,6 +1642,8 @@ static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
enum port port = intel_ddi_get_encoder_port(encoder);
+ struct intel_connector *intel_connector = intel_dp->attached_connector;
+ struct drm_connector *connector = &intel_connector->base;
intel_dp_set_link_params(intel_dp, link_rate, lane_count,
link_mst);
@@ -1652,7 +1654,17 @@ 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(&connector->i915_modeset_retry_work);
+ } else
+ connector->link_train_retry = false;
+
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 aae7f82..78246ba 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -313,6 +313,7 @@ static int intel_dp_link_rate_index(struct intel_dp *intel_dp, int *common_rates
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 +327,26 @@ static int intel_dp_link_rate_index(struct intel_dp *intel_dp, int *common_rates
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");
+ connector->link_train_retry = false;
+ intel_dp->link_train_failed_link_rate = 0;
+ intel_dp->link_rate_index = -1;
+ }
+ }
+ 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);
@@ -1610,6 +1629,14 @@ static int intel_dp_compute_bpp(struct intel_dp *intel_dp,
if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK)
return false;
+ /* 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],
@@ -4394,6 +4421,10 @@ static bool intel_digital_port_connected(struct drm_i915_private *dev_priv,
/* Can't disconnect eDP, but you can close the lid... */
if (is_edp(intel_dp))
status = edp_detect(intel_dp);
+ else if (intel_dp->link_train_failed) {
+ intel_dp->link_train_failed = false;
+ goto out;
+ }
else if (intel_digital_port_connected(to_i915(dev),
dp_to_dig_port(intel_dp)))
status = intel_dp_detect_dpcd(intel_dp);
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 5760420..4b4bed6 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -890,6 +890,10 @@ 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;
@@ -1403,7 +1407,7 @@ 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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