[PATCH v2 03/34] drm/i915/dp_link_caps: Add support for link rate, lane count iteration orders

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

Add support for iterating configurations in either link rate/lane count
or lane count/link rate order. Both orders are required for DP SST
connector types: the former for computing the connector state during a
modeset, and the latter for selecting a fallback configuration after a
link training failure.

Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 .../gpu/drm/i915/display/intel_dp_link_caps.c | 50 +++++++++++++++++++
 1 file changed, 50 insertions(+)

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 d0a863b00b458..fe5a11efbe67b 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
@@ -122,6 +122,13 @@ struct intel_dp_link_caps {
 		u8 lane_count_exp:INTEL_DP_LANE_COUNT_EXP_BITS;
 	} configs[INTEL_DP_MAX_LINK_CONFIGS];
 
+	/*
+	 * Indices to intel_dp_link_caps::configs[] in rate/lane count,
+	 * lane_count/rate order.
+	 */
+	u8 rate_lane_map[INTEL_DP_MAX_LINK_CONFIGS];
+	u8 lane_rate_map[INTEL_DP_MAX_LINK_CONFIGS];
+
 	/*
 	 * Forced parameters requested via debugfs. Remains set across sink
 	 * disconnects.
@@ -350,6 +357,34 @@ static int link_config_cmp_by_bw(const void *a, const void *b, const void *p)
 	       intel_dp_link_config_rate(link_caps, lce_b);
 }
 
+static int link_config_cmp_by_rate_lane(const void *a, const void *b, const void *p)
+{
+	const struct intel_dp_link_caps *link_caps = p;
+	u8 *lce_a_idx = (u8 *)a;
+	u8 *lce_b_idx = (u8 *)b;
+	const struct intel_dp_link_config_entry *lce_a = &link_caps->configs[*lce_a_idx];
+	const struct intel_dp_link_config_entry *lce_b = &link_caps->configs[*lce_b_idx];
+
+	if (lce_a->link_rate_idx != lce_b->link_rate_idx)
+		return lce_a->link_rate_idx - lce_b->link_rate_idx;
+
+	return lce_a->lane_count_exp - lce_b->lane_count_exp;
+}
+
+static int link_config_cmp_by_lane_rate(const void *a, const void *b, const void *p)
+{
+	const struct intel_dp_link_caps *link_caps = p;
+	u8 *lce_a_idx = (u8 *)a;
+	u8 *lce_b_idx = (u8 *)b;
+	const struct intel_dp_link_config_entry *lce_a = &link_caps->configs[*lce_a_idx];
+	const struct intel_dp_link_config_entry *lce_b = &link_caps->configs[*lce_b_idx];
+
+	if (lce_a->lane_count_exp != lce_b->lane_count_exp)
+		return lce_a->lane_count_exp - lce_b->lane_count_exp;
+
+	return lce_a->link_rate_idx - lce_b->link_rate_idx;
+}
+
 /* Return %true if the supported link parameters have changed. */
 bool intel_dp_link_caps_update(struct intel_dp_link_caps *link_caps,
 			       const int *rates, int num_rates, int max_lane_count)
@@ -404,6 +439,21 @@ bool intel_dp_link_caps_update(struct intel_dp_link_caps *link_caps,
 	       link_config_cmp_by_bw, NULL,
 	       intel_dp);
 
+	for (i = 0; i < link_caps->num_configs; i++) {
+		link_caps->rate_lane_map[i] = i;
+		link_caps->lane_rate_map[i] = i;
+	}
+
+	sort_r(link_caps->rate_lane_map, link_caps->num_configs,
+	       sizeof(link_caps->rate_lane_map[0]),
+	       link_config_cmp_by_rate_lane, NULL,
+	       link_caps);
+
+	sort_r(link_caps->lane_rate_map, link_caps->num_configs,
+	       sizeof(link_caps->lane_rate_map[0]),
+	       link_config_cmp_by_lane_rate, NULL,
+	       link_caps);
+
 	return link_params_changed;
 }
 
-- 
2.49.1