[PATCH 075/108] drm/i915/dp_link_training: Look up configurations using fuzzy rate matching

[Imre Deak <imre.deak@intel.com>]

Look up an allowed link configuration during the BW-order fallback using
a fuzzy rate match to account for differences between the computed link
rate and the nominal rate tracked by the allowed configurations.

Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 .../gpu/drm/i915/display/intel_dp_link_caps.c | 20 -------------------
 .../gpu/drm/i915/display/intel_dp_link_caps.h |  2 --
 .../drm/i915/display/intel_dp_link_training.c | 19 +++++++++---------
 3 files changed, 10 insertions(+), 31 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_caps.c b/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
index 103490eec3d23..7643c468588d0 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
@@ -878,26 +878,6 @@ bool intel_dp_link_caps_update(struct intel_dp_link_caps *link_caps,
 	return link_params_changed;
 }
 
-int intel_dp_link_config_index(struct intel_dp_link_caps *link_caps,
-			       int link_rate, int lane_count)
-{
-	const struct intel_dp_link_caps_config_table *table = &link_caps->config_table;
-	int link_rate_idx = intel_dp_rate_index(table->rates, table->num_rates,
-						link_rate);
-	int lane_count_exp = ilog2(lane_count);
-	int i;
-
-	for (i = 0; i < table->num_configs; i++) {
-		const struct intel_dp_link_config_entry *lc = &table->configs[i];
-
-		if (lc->lane_count_exp == lane_count_exp &&
-		    lc->link_rate_idx == link_rate_idx)
-			return i;
-	}
-
-	return -1;
-}
-
 /**
  * intel_dp_link_caps_reset - reset link capability restrictions
  * @link_caps: link capabilities state
diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_caps.h b/drivers/gpu/drm/i915/display/intel_dp_link_caps.h
index b380beedd8990..6599325932ab6 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_link_caps.h
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_caps.h
@@ -100,8 +100,6 @@ void intel_dp_link_caps_get_forced_params(struct intel_dp_link_caps *link_caps,
 					  struct intel_dp_link_config *forced_params);
 u32 intel_dp_link_caps_get_allowed_config_mask(struct intel_dp_link_caps *link_caps);
 
-int intel_dp_link_config_index(struct intel_dp_link_caps *link_caps,
-			       int link_rate, int lane_count);
 bool
 intel_dp_link_caps_get_config_by_pos(struct intel_dp_link_caps *link_caps,
 				     struct intel_dp_link_caps_config_order config_order,
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 9dd302bb4968b..fb20795a7086f 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
@@ -1782,8 +1782,16 @@ static bool reduce_link_params_in_bw_order(struct intel_dp *intel_dp,
 	forced_rate = forced_params.rate;
 	forced_lane_count = forced_params.lane_count;
 
-	i = intel_dp_link_config_index(intel_dp->link.caps,
-				       crtc_state->port_clock, crtc_state->lane_count);
+	/*
+	 * The computed link rate could differ from the nominal rate
+	 * due to platform specific PLL restrictions, so use a fuzzy
+	 * matching.
+	 */
+	i = intel_dp_link_caps_find_allowed_config_pos(link_caps,
+						       bw_asc_order,
+						       INTEL_DP_LINK_CAPS_CONFIG_MATCH_FUZZY_RATE,
+						       &link_config);
+
 	for (i--; i >= 0; i--) {
 		bool config_found;
 
@@ -1794,13 +1802,6 @@ static bool reduce_link_params_in_bw_order(struct intel_dp *intel_dp,
 		if (drm_WARN_ON(display->drm, !config_found))
 			return false;
 
-		/*
-		 * Atm, the index of the configuration must match its
-		 * iteration position.
-		 */
-		if (drm_WARN_ON(display->drm, link_config_idx != i))
-			return false;
-
 		link_rate = link_config.rate;
 		lane_count = link_config.lane_count;
 
-- 
2.49.1