[PATCH v2 07/34] drm/i915/dp_link_caps: Add filter for enabled link configurations

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

Add a filter for enabled link configurations to the link capability
state.

This allows fallback code to disable only the configuration that failed
link training, instead of constraining later modesets via maximum link
rate or lane count. The code only needs to exclude the failed
configuration from the allowed set; all other supported configurations
remain available.

Use the filter when computing the allowed configuration set and when
validating maximum link limits.

Follow-up changes will switch the fallback code to disable individual
configurations through this filter.

v2:
- Rebase on changes using a filter object instead of a mask of
  configuration indices.
- Track the enabled configurations instead of the disabled ones.

Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 .../gpu/drm/i915/display/intel_dp_link_caps.c | 38 +++++++++++++++++--
 1 file changed, 34 insertions(+), 4 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 5976e85bb2729..03e40e8d24fb6 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
@@ -130,6 +130,37 @@ struct intel_dp_link_caps {
 	u8 rate_lane_map[INTEL_DP_MAX_LINK_CONFIGS];
 	u8 lane_rate_map[INTEL_DP_MAX_LINK_CONFIGS];
 
+	/*
+	 * Filter of configurations enabled for the current sink
+	 * connection.
+	 *
+	 * Each bit in the filter's configuration mask corresponds to a
+	 * configuration index in the intel_dp_link_caps::configs[] array.
+	 *
+	 * All configurations start out enabled in the filter after a
+	 * new sink is connected. Users disable configurations afterwards
+	 * via the link caps API. All configurations get re-enabled
+	 * internally in the following cases:
+	 * - when forcing a link rate or lane count
+	 * - when intel_dp_link_caps_update(reset=true) is called after
+	 *   a new sink is connected
+	 * - when intel_dp_link_caps_update(reset=false) with changed
+	 *   link capabilities is called
+	 * - when intel_dp_link_caps_reset() is called after a new sink
+	 *   is connected
+	 */
+	struct intel_dp_link_caps_filter enabled_configs;
+
+	/*
+	 * Allowed configurations are the supported configurations defined by
+	 * config_table.rates and config_table.max_lane_count, constrained by
+	 * config_table.enabled_configs and the forced_params and
+	 * max_limits values below.
+	 *
+	 * See get_allowed_config_filter() for the filter of these
+	 * configurations.
+	 */
+
 	/*
 	 * Forced parameters requested via debugfs. Remains set across sink
 	 * disconnects.
@@ -454,8 +485,7 @@ get_allowed_config_filter(struct intel_dp_link_caps *link_caps)
 
 	intel_dp_link_caps_get_forced_params(link_caps, &forced_params);
 
-	/* TODO: Get filter for enabled configs. */
-	return calc_allowed_config_filter(link_caps, INTEL_DP_LINK_CAPS_FILTER_ALL,
+	return calc_allowed_config_filter(link_caps, link_caps->enabled_configs,
 					  &link_caps->max_limits, &forced_params);
 }
 
@@ -571,8 +601,7 @@ static bool max_link_limits_valid(struct intel_dp_link_caps *link_caps,
 	/* TODO: Validate max_link_limits->rate against the source supported rates. */
 
 	intel_dp_link_caps_get_forced_params(link_caps, &forced_params);
-	/* TODO: Get filter for enabled configs. */
-	allowed_configs = calc_allowed_config_filter(link_caps, INTEL_DP_LINK_CAPS_FILTER_ALL,
+	allowed_configs = calc_allowed_config_filter(link_caps, link_caps->enabled_configs,
 						     max_link_limits, &forced_params);
 
 	return allowed_configs.config_mask != 0;
@@ -1095,6 +1124,7 @@ struct intel_dp_link_caps *intel_dp_link_caps_init(struct intel_dp *intel_dp)
 		return NULL;
 
 	link_caps->dp = intel_dp;
+	link_caps->enabled_configs = INTEL_DP_LINK_CAPS_FILTER_ALL;
 
 	return link_caps;
 }
-- 
2.49.1